[dev.boringcrypto.go1.18] all: merge go1.18 into dev.boringcrypto.go1.18

Change-Id: Ib2bfa4940b7b054d54f8ee998c63beb32c6afd51

CONTRIBUTORS

@@ -120,6 +120,7 @@ Alex Kohler <alexjohnkohler@gmail.com>
 Alex Myasoedov <msoedov@gmail.com>
 Alex Opie <amtopie@gmail.com>
 Alex Plugaru <alex@plugaru.org> <alexandru.plugaru@gmail.com>
+Alex Schade <39062967+aschade92@users.noreply.github.com>
 Alex Schroeder <alex@gnu.org>
 Alex Sergeyev <abc@alexsergeyev.com>
 Alex Tokarev <aleksator@gmail.com>
@@ -135,6 +136,7 @@ Alexander Klauer <Alexander.Klauer@googlemail.com>
 Alexander Kucherenko <alxkchr@gmail.com>
 Alexander Larsson <alexander.larsson@gmail.com>
 Alexander Lourier <aml@rulezz.ru>
+Alexander Melentyev <alexander@melentyev.org>
 Alexander Menzhinsky <amenzhinsky@gmail.com>
 Alexander Morozov <lk4d4math@gmail.com>
 Alexander Neumann <alexander@bumpern.de>
@@ -145,6 +147,7 @@ Alexander Polcyn <apolcyn@google.com>
 Alexander Rakoczy <alex@golang.org>
 Alexander Reece <awreece@gmail.com>
 Alexander Surma <surma@surmair.de>
+Alexander Yastrebov <yastrebov.alex@gmail.com>
 Alexander Zhavnerchik <alex.vizor@gmail.com>
 Alexander Zillion <alex@alexzillion.com>
 Alexander Zolotov <goldifit@gmail.com>
@@ -179,6 +182,7 @@ Alok Menghrajani <alok.menghrajani@gmail.com>
 Alwin Doss <alwindoss84@gmail.com>
 Aman Gupta <aman@tmm1.net>
 Amarjeet Anand <amarjeetanandsingh@gmail.com>
+Amelia Downs <adowns@vmware.com>
 Amir Mohammad Saied <amir@gluegadget.com>
 Amit Kumar <mittalmailbox@gmail.com>
 Amr Mohammed <merodiro@gmail.com>
@@ -191,6 +195,7 @@ Anatol Pomozov <anatol.pomozov@gmail.com>
 Anders Pearson <anders@columbia.edu>
 Anderson Queiroz <contato@andersonq.eti.br>
 André Carvalho <asantostc@gmail.com>
+Andre Marianiello <andremarianiello@users.noreply.github.com>
 André Martins <aanm90@gmail.com>
 Andre Nathan <andrenth@gmail.com>
 Andrea Nodari <andrea.nodari91@gmail.com>
@@ -221,6 +226,7 @@ Andrew Gerrand <adg@golang.org>
 Andrew Harding <andrew@spacemonkey.com>
 Andrew Jackura <ajackura@google.com>
 Andrew Kemm <andrewkemm@gmail.com>
+Andrew LeFevre <capnspacehook@gmail.com>
 Andrew Louis <alouis@digitalocean.com>
 Andrew Lutomirski <andy@luto.us>
 Andrew Medvedev <andrew.y.medvedev@gmail.com>
@@ -234,6 +240,7 @@ Andrew Stormont <astormont@racktopsystems.com>
 Andrew Stribblehill <ads@wompom.org>
 Andrew Szeto <andrew@jabagawee.com>
 Andrew Todd <andrew.todd@wework.com>
+Andrew Wansink <wansink@uber.com>
 Andrew Werner <andrew@upthere.com> <awerner32@gmail.com>
 Andrew Wilkins <axwalk@gmail.com>
 Andrew Williams <williams.andrew@gmail.com>
@@ -283,6 +290,7 @@ Antonio Bibiano <antbbn@gmail.com>
 Antonio Garcia <garcia.olais@gmail.com>
 Antonio Huete Jimenez <tuxillo@quantumachine.net>
 Antonio Murdaca <runcom@redhat.com>
+Antonio Ojea <antonio.ojea.garcia@gmail.com>
 Antonio Troina <thoeni@gmail.com>
 Anze Kolar <me@akolar.com>
 Aofei Sheng <aofei@aofeisheng.com>
@@ -290,6 +298,7 @@ Apisak Darakananda <pongad@gmail.com>
 Aram Hăvărneanu <aram@mgk.ro>
 Araragi Hokuto <kanseihonbucho@protonmail.com>
 Arash Bina <arash@arash.io>
+Archana Ravindar <aravind5@in.ibm.com>
 Arda Güçlü <ardaguclu@gmail.com>
 Areski Belaid <areski@gmail.com>
 Ariel Mashraki <ariel@mashraki.co.il>
@@ -299,6 +308,7 @@ Arnaud Ysmal <arnaud.ysmal@gmail.com>
 Arne Hormann <arnehormann@gmail.com>
 Arnout Engelen <arnout@bzzt.net>
 Aron Nopanen <aron.nopanen@gmail.com>
+Arran Walker <arran.walker@fiveturns.org>
 Artem Alekseev <artem.alekseev@intel.com>
 Artem Khvastunov <artem.khvastunov@jetbrains.com>
 Artem Kolin <artemkaxboy@gmail.com>
@@ -337,6 +347,7 @@ Balaram Makam <bmakam.qdt@qualcommdatacenter.com>
 Balazs Lecz <leczb@google.com>
 Baokun Lee <nototon@gmail.com> <bk@golangcn.org>
 Barnaby Keene <accounts@southcla.ws>
+Bartłomiej Klimczak <bartlomiej.klimczak88@gmail.com>
 Bartosz Grzybowski <melkorm@gmail.com>
 Bartosz Oler <brtsz@google.com>
 Bassam Ojeil <bojeil@google.com>
@@ -368,6 +379,7 @@ Benny Siegert <bsiegert@gmail.com>
 Benoit Sigoure <tsunanet@gmail.com>
 Berengar Lehr <Berengar.Lehr@gmx.de>
 Berkant Ipek <41230766+0xbkt@users.noreply.github.com>
+Beth Brown <ecbrown@google.com>
 Bharath Kumar Uppala <uppala.bharath@gmail.com>
 Bharath Thiruveedula <tbharath91@gmail.com>
 Bhavin Gandhi <bhavin7392@gmail.com>
@@ -430,6 +442,7 @@ Brian Ketelsen <bketelsen@gmail.com>
 Brian Slesinsky <skybrian@google.com>
 Brian Smith <ohohvi@gmail.com>
 Brian Starke <brian.starke@gmail.com>
+Bruce Huang <helbingxxx@gmail.com>
 Bryan Alexander <Kozical@msn.com>
 Bryan Boreham <bjboreham@gmail.com>
 Bryan C. Mills <bcmills@google.com>
@@ -482,17 +495,21 @@ Charles Kenney <charlesc.kenney@gmail.com>
 Charles L. Dorian <cldorian@gmail.com>
 Charles Lee <zombie.fml@gmail.com>
 Charles Weill <weill@google.com>
+Charlie Getzen <charlie@bolt.com>
 Charlie Moog <moogcharlie@gmail.com>
 Charlotte Brandhorst-Satzkorn <catzkorn@gmail.com>
 Chauncy Cullitan <chauncyc@google.com>
 Chen Zhidong <njutczd@gmail.com>
 Chen Zhihan <energiehund@gmail.com>
+Cheng Wang <wangchengiscool@gmail.com>
 Cherry Mui <cherryyz@google.com>
 Chew Choon Keat <choonkeat@gmail.com>
+Chia-Chi Hsu <wuchi5457@gmail.com>
 Chiawen Chen <golopot@gmail.com>
 Chirag Sukhala <cchirag77@gmail.com>
 Cholerae Hu <choleraehyq@gmail.com>
 Chotepud Teo <AlexRouSg@users.noreply.github.com>
+Chressie Himpel <chressie@google.com>
 Chris Ball <chris@printf.net>
 Chris Biscardi <chris@christopherbiscardi.com>
 Chris Broadfoot <cbro@golang.org>
@@ -570,6 +587,7 @@ Cuong Manh Le <cuong@orijtech.com>
 Curtis La Graff <curtis@lagraff.me>
 Cyrill Schumacher <cyrill@schumacher.fm>
 Dai Jie <gzdaijie@gmail.com>
+Dai Wentao <dwt136@gmail.com>
 Daisuke Fujita <dtanshi45@gmail.com>
 Daisuke Suzuki <daisuzu@gmail.com>
 Daker Fernandes Pinheiro <daker.fernandes.pinheiro@intel.com>
@@ -603,6 +621,7 @@ Daniel Langner <s8572327@gmail.com>
 Daniel Lidén <daniel.liden.87@gmail.com>
 Daniel Lublin <daniel@lublin.se>
 Daniel Mangum <georgedanielmangum@gmail.com>
+Daniel Marshall <daniel.marshall2@ibm.com>
 Daniel Martí <mvdan@mvdan.cc>
 Daniel McCarney <cpu@letsencrypt.org>
 Daniel Morsing <daniel.morsing@gmail.com>
@@ -727,6 +746,7 @@ Dmitry Mottl <dmitry.mottl@gmail.com>
 Dmitry Neverov <dmitry.neverov@gmail.com>
 Dmitry Savintsev <dsavints@gmail.com>
 Dmitry Yakunin <nonamezeil@gmail.com>
+Dmytro Shynkevych <dm.shynk@gmail.com>
 Doga Fincan <doga@icloud.com>
 Domas Tamašauskas <puerdomus@gmail.com>
 Domen Ipavec <domen@ipavec.net>
@@ -751,6 +771,7 @@ Dustin Herbison <djherbis@gmail.com>
 Dustin Long <dustmop@gmail.com>
 Dustin Sallings <dsallings@gmail.com>
 Dustin Shields-Cloues <dcloues@gmail.com>
+Dustin Spicuzza <dustin.spicuzza@gmail.com>
 Dvir Volk <dvir@everything.me> <dvirsky@gmail.com>
 Dylan Waits <dylan@waits.io>
 Ed Schouten <ed@nuxi.nl>
@@ -810,9 +831,11 @@ Erin Masatsugu <erin.masatsugu@gmail.com>
 Ernest Chiang <ernest_chiang@htc.com>
 Erwin Oegema <blablaechthema@hotmail.com>
 Esko Luontola <esko.luontola@gmail.com>
+Ethan Anderson <eanderson@atlassian.com>
 Ethan Burns <eaburns@google.com>
 Ethan Hur <ethan0311@gmail.com>
 Ethan Miller <eamiller@us.ibm.com>
+Ethan Reesor <ethan.reesor@gmail.com>
 Euan Kemp <euank@euank.com>
 Eugene Formanenko <mo4islona@gmail.com>
 Eugene Kalinin <e.v.kalinin@gmail.com>
@@ -831,8 +854,10 @@ Evgeniy Polyakov <zbr@ioremap.net>
 Ewan Chou <coocood@gmail.com>
 Ewan Valentine <ewan.valentine89@gmail.com>
 Eyal Posener <posener@gmail.com>
+F. Talha Altınel <talhaaltinel@hotmail.com>
 Fabian Wickborn <fabian@wickborn.net>
 Fabian Zaremba <fabian@youremail.eu>
+Fabio Falzoi <fabio.falzoi84@gmail.com>
 Fabrizio Milo <mistobaan@gmail.com>
 Faiyaz Ahmed <ahmedf@vmware.com>
 Fan Hongjian <fan.howard@gmail.com>
@@ -861,21 +886,25 @@ Firmansyah Adiputra <frm.adiputra@gmail.com>
 Florian Forster <octo@google.com>
 Florian Uekermann <florian@uekermann-online.de> <f1@uekermann-online.de>
 Florian Weimer <fw@deneb.enyo.de>
+Florin Papa <fpapa@google.com>
 Florin Patan <florinpatan@gmail.com>
 Folke Behrens <folke@google.com>
 Ford Hurley <ford.hurley@gmail.com>
+Forest Johnson <forest.n.johnson@gmail.com>
 Francesc Campoy <campoy@golang.org>
 Francesco Guardiani <francescoguard@gmail.com>
 Francesco Renzi <rentziass@gmail.com>
 Francisco Claude <fclaude@recoded.cl>
 Francisco Rojas <francisco.rojas.gallegos@gmail.com>
 Francisco Souza <franciscossouza@gmail.com>
+Frank Chiarulli Jr <frank@frankchiarulli.com>
 Frank Schroeder <frank.schroeder@gmail.com>
 Frank Somers <fsomers@arista.com>
 Frederic Guillot <frederic.guillot@gmail.com>
 Frederick Kelly Mayle III <frederickmayle@gmail.com>
 Frederik Ring <frederik.ring@gmail.com>
 Frederik Zipp <fzipp@gmx.de>
+Frediano Ziglio <freddy77@gmail.com>
 Fredrik Enestad <fredrik.enestad@soundtrackyourbrand.com>
 Fredrik Forsmo <fredrik.forsmo@gmail.com>
 Fredrik Wallgren <fredrik.wallgren@gmail.com>
@@ -914,6 +943,7 @@ Geon Kim <geon0250@gmail.com>
 Georg Reinke <guelfey@gmail.com>
 George Gkirtsou <ggirtsou@gmail.com>
 George Hartzell <hartzell@alerce.com>
+George Looshch <looshch@loosh.ch>
 George Shammas <george@shamm.as> <georgyo@gmail.com>
 George Tsilias <tsiliasg@gmail.com>
 Gerasimos (Makis) Maropoulos <kataras2006@hotmail.com>
@@ -954,19 +984,27 @@ GitHub User @fatedier (7346661) <fatedier@gmail.com>
 GitHub User @frennkie (6499251) <mail@rhab.de>
 GitHub User @geedchin (11672310) <geedchin@gmail.com>
 GitHub User @GrigoriyMikhalkin (3637857) <grigoriymikhalkin@gmail.com>
+GitHub User @Gusted (25481501) <williamzijl7@hotmail.com>
 GitHub User @hengwu0 (41297446) <41297446+hengwu0@users.noreply.github.com>
 GitHub User @hitzhangjie (3725760) <hit.zhangjie@gmail.com>
+GitHub User @hkhere (33268704) <33268704+hkhere@users.noreply.github.com>
+GitHub User @hopehook (7326168) <hopehook.com@gmail.com>
 GitHub User @hqpko (13887251) <whaibin01@hotmail.com>
+GitHub User @Illirgway (5428603) <illirgway@gmail.com>
 GitHub User @itchyny (375258) <itchyny@hatena.ne.jp>
 GitHub User @jinmiaoluo (39730824) <jinmiaoluo@icloud.com>
 GitHub User @jopbrown (6345470) <msshane2008@gmail.com>
 GitHub User @kazyshr (30496953) <kazyshr0301@gmail.com>
 GitHub User @kc1212 (1093806) <kc1212@users.noreply.github.com>
 GitHub User @komisan19 (18901496) <komiyama6219@gmail.com>
+GitHub User @korzhao (64203902) <korzhao95@gmail.com>
 GitHub User @Kropekk (13366453) <kamilkropiewnicki@gmail.com>
+GitHub User @lgbgbl (65756378) <lgbgbl@qq.com>
 GitHub User @lhl2617 (33488131) <l.h.lee2617@gmail.com>
 GitHub User @linguohua (3434367) <lghchinaidea@gmail.com>
+GitHub User @lloydchang (1329685) <lloydchang@gmail.com>
 GitHub User @LotusFenn (13775899) <fenn.lotus@gmail.com>
+GitHub User @luochuanhang (96416201) <chuanhangluo@gmail.com>
 GitHub User @ly303550688 (11519839) <yang.liu636@gmail.com>
 GitHub User @madiganz (18340029) <zacharywmadigan@gmail.com>
 GitHub User @maltalex (10195391) <code@bit48.net>
@@ -976,6 +1014,7 @@ GitHub User @micnncim (21333876) <micnncim@gmail.com>
 GitHub User @mkishere (224617) <224617+mkishere@users.noreply.github.com>
 GitHub User @nu50218 (40682920) <nu_ll@icloud.com>
 GitHub User @OlgaVlPetrova (44112727) <OVPpetrova@gmail.com>
+GitHub User @pierwill (19642016) <pierwill@users.noreply.github.com>
 GitHub User @pityonline (438222) <pityonline@gmail.com>
 GitHub User @po3rin (29445112) <abctail30@gmail.com>
 GitHub User @pokutuna (57545) <popopopopokutuna@gmail.com>
@@ -983,13 +1022,18 @@ GitHub User @povsister (11040951) <pov@mahou-shoujo.moe>
 GitHub User @pytimer (17105586) <lixin20101023@gmail.com>
 GitHub User @qcrao (7698088) <qcrao91@gmail.com>
 GitHub User @ramenjuniti (32011829) <ramenjuniti@gmail.com>
+GitHub User @renthraysk (30576707) <renthraysk@gmail.com>
+GitHub User @roudkerk (52280478) <roudkerk@google.com>
 GitHub User @saitarunreddy (21041941) <saitarunreddypalla@gmail.com>
 GitHub User @SataQiu (9354727) <shidaqiu2018@gmail.com>
+GitHub User @seifchen (23326132) <chenxuefeng1207@gmail.com>
 GitHub User @shogo-ma (9860598) <Choroma194@gmail.com>
 GitHub User @sivchari (55221074) <shibuuuu5@gmail.com>
 GitHub User @skanehira (7888591) <sho19921005@gmail.com>
 GitHub User @soolaugust (10558124) <soolaugust@gmail.com>
 GitHub User @surechen (7249331) <surechen17@gmail.com>
+GitHub User @syumai (6882878) <syumai@gmail.com>
+GitHub User @tangxi666 (48145175) <tx1275044634@gmail.com>
 GitHub User @tatsumack (4510569) <tatsu.mack@gmail.com>
 GitHub User @tell-k (26263) <ffk2005@gmail.com>
 GitHub User @tennashi (10219626) <tennashio@gmail.com>
@@ -999,6 +1043,7 @@ GitHub User @unbyte (5772358) <i@shangyes.net>
 GitHub User @uropek (39370426) <uropek@gmail.com>
 GitHub User @utkarsh-extc (53217283) <utkarsh.extc@gmail.com>
 GitHub User @witchard (4994659) <witchard@hotmail.co.uk>
+GitHub User @wmdngngng (22067700) <wangmingdong@gmail.com>
 GitHub User @wolf1996 (5901874) <ksgiv37@gmail.com>
 GitHub User @yah01 (12216890) <kagaminehuan@gmail.com>
 GitHub User @yuanhh (1298735) <yuan415030@gmail.com>
@@ -1029,12 +1074,14 @@ Guilherme Garnier <guilherme.garnier@gmail.com>
 Guilherme Goncalves <guilhermeaugustosg@gmail.com>
 Guilherme Rezende <guilhermebr@gmail.com>
 Guilherme Souza <32180229+gqgs@users.noreply.github.com>
+Guillaume Blaquiere <guillaume.blaquiere@gmail.com>
 Guillaume J. Charmes <guillaume@charmes.net>
 Guillaume Sottas <guillaumesottas@gmail.com>
 Günther Noack <gnoack@google.com>
 Guobiao Mei <meiguobiao@gmail.com>
 Guodong Li <guodongli@google.com>
 Guoliang Wang <iamwgliang@gmail.com>
+Guoqi Chen <chenguoqi@loongson.cn>
 Gustav Paul <gustav.paul@gmail.com>
 Gustav Westling <gustav@westling.xyz>
 Gustavo Franco <gustavorfranco@gmail.com>
@@ -1050,6 +1097,8 @@ Hang Qian <hangqian90@gmail.com>
 Hanjun Kim <hallazzang@gmail.com>
 Hanlin He <hanling.he@gmail.com>
 Hanlin Shi <shihanlin9@gmail.com>
+Hans Nielsen <hans@stackallocated.com>
+Hao Mou <mouhao.mu@gmail.com>
 Haoran Luo <haoran.luo@chaitin.com>
 Haosdent Huang <haosdent@gmail.com>
 Harald Nordgren <haraldnordgren@gmail.com>
@@ -1126,6 +1175,7 @@ Igor Zhilianin <igor.zhilianin@gmail.com>
 Ikko Ashimine <eltociear@gmail.com>
 Illya Yalovyy <yalovoy@gmail.com>
 Ilya Chukov <56119080+Elias506@users.noreply.github.com>
+Ilya Mateyko <me@astrophena.name>
 Ilya Sinelnikov <sidhmangh@gmail.com>
 Ilya Tocar <ilya.tocar@intel.com>
 INADA Naoki <songofacandy@gmail.com>
@@ -1157,6 +1207,7 @@ Jaana Burcu Dogan <jbd@google.com> <jbd@golang.org> <burcujdogan@gmail.com>
 Jaap Aarts <jaap.aarts1@gmail.com>
 Jack Britton <jackxbritton@gmail.com>
 Jack Lindamood <jlindamo@justin.tv>
+Jack You <jamesyou@google.com>
 Jacob Baskin <jbaskin@google.com>
 Jacob Blain Christen <dweomer5@gmail.com>
 Jacob H. Haven <jacob@cloudflare.com>
@@ -1165,6 +1216,7 @@ Jacob Walker <jacobwalker0814@gmail.com>
 Jaden Teng <long.asyn@gmail.com>
 Jae Kwon <jae@tendermint.com>
 Jake B <doogie1012@gmail.com>
+Jake Ciolek <jakub@ciolek.dev>
 Jakob Borg <jakob@nym.se>
 Jakob Weisblat <jakobw@mit.edu>
 Jakub Čajka <jcajka@redhat.com>
@@ -1183,6 +1235,7 @@ James Eady <jmeady@google.com>
 James Fennell <jpfennell@google.com>
 James Fysh <james.fysh@gmail.com>
 James Gray <james@james4k.com>
+James Harris <mailjamesharris@gmail.com>
 James Hartig <fastest963@gmail.com>
 James Kasten <jdkasten@google.com>
 James Lawrence <jljatone@gmail.com>
@@ -1246,6 +1299,7 @@ Jean de Klerk <deklerk@google.com>
 Jean-André Santoni <jean.andre.santoni@gmail.com>
 Jean-François Bustarret <jf@bustarret.com>
 Jean-Francois Cantin <jfcantin@gmail.com>
+Jean-Hadrien Chabran <jh@chabran.fr>
 Jean-Marc Eurin <jmeurin@google.com>
 Jean-Nicolas Moal <jn.moal@gmail.com>
 Jed Denlea <jed@fastly.com>
@@ -1260,6 +1314,7 @@ Jeff Johnson <jrjohnson@google.com>
 Jeff R. Allen <jra@nella.org> <jeff.allen@gmail.com>
 Jeff Sickel <jas@corpus-callosum.com>
 Jeff Wendling <jeff@spacemonkey.com>
+Jeff Wentworth <j.wentworth@gmail.com>
 Jeff Widman <jeff@jeffwidman.com>
 Jeffrey H <jeffreyh192@gmail.com>
 Jelte Fennema <github-tech@jeltef.nl>
@@ -1282,6 +1337,7 @@ Jesús Espino <jespinog@gmail.com>
 Jia Zhan <jzhan@uber.com>
 Jiacai Liu <jiacai2050@gmail.com>
 Jiahao Lu <lujjjh@gmail.com>
+Jiahua Wang <wjh180909@gmail.com>
 Jianing Yu <jnyu@google.com>
 Jianqiao Li <jianqiaoli@google.com>
 Jiayu Yi <yijiayu@gmail.com>
@@ -1298,10 +1354,12 @@ Jingcheng Zhang <diogin@gmail.com>
 Jingguo Yao <yaojingguo@gmail.com>
 Jingnan Si <jingnan.si@gmail.com>
 Jinkun Zhang <franksnolf@gmail.com>
+Jinwen Wo <wojinwen@huawei.com>
 Jiong Du <londevil@gmail.com>
 Jirka Daněk <dnk@mail.muni.cz>
 Jiulong Wang <jiulongw@gmail.com>
 Joakim Sernbrant <serbaut@gmail.com>
+Jochen Weber <jochen.weber80@gmail.com>
 Joe Bowbeer <joe.bowbeer@gmail.com>
 Joe Cortopassi <joe@joecortopassi.com>
 Joe Farrell <joe2farrell@gmail.com>
@@ -1324,6 +1382,7 @@ Johan Euphrosine <proppy@google.com>
 Johan Jansson <johan.jansson@iki.fi>
 Johan Knutzen <johan@senri.se>
 Johan Sageryd <j@1616.se>
+Johannes Altmanninger <aclopte@gmail.com>
 Johannes Huning <johannes.huning@gmail.com>
 John Asmuth <jasmuth@gmail.com>
 John Bampton <jbampton@gmail.com>
@@ -1338,10 +1397,12 @@ John Howard Palevich <jack.palevich@gmail.com>
 John Jago <johnjago@protonmail.com>
 John Jeffery <jjeffery@sp.com.au>
 John Jenkins <twodopeshaggy@gmail.com>
+John Kelly <jkelly@squarespace.com>
 John Leidegren <john.leidegren@gmail.com>
 John McCabe <john@johnmccabe.net>
 John Moore <johnkenneth.moore@gmail.com>
 John Newlin <jnewlin@google.com>
+John Olheiser <john.olheiser@gmail.com>
 John Papandriopoulos <jpap.code@gmail.com>
 John Potocny <johnp@vividcortex.com>
 John R. Lenton <jlenton@gmail.com>
@@ -1382,6 +1443,7 @@ Jordan Rupprecht <rupprecht@google.com>
 Jordi Martin <jordimartin@gmail.com>
 Jorge Araya <jorgejavieran@yahoo.com.mx>
 Jorge L. Fatta <jorge.fatta@auth0.com>
+Jorge Troncoso <jatron@google.com>
 Jos Visser <josv@google.com>
 Josa Gesell <josa@gesell.me>
 Jose Luis Vázquez González <josvazg@gmail.com>
@@ -1508,6 +1570,7 @@ Keyuan Li <keyuanli123@gmail.com>
 Kezhu Wang <kezhuw@gmail.com>
 Khosrow Moossavi <khos2ow@gmail.com>
 Kieran Colford <kieran@kcolford.com>
+Kieran Gorman <kieran.j.gorman@gmail.com>
 Kim Shrier <kshrier@racktopsystems.com>
 Kim Yongbin <kybinz@gmail.com>
 Kir Kolyshkin <kolyshkin@gmail.com>
@@ -1577,6 +1640,7 @@ Leonel Quinteros <leonel.quinteros@gmail.com>
 Lev Shamardin <shamardin@gmail.com>
 Lewin Bormann <lewin.bormann@gmail.com>
 Lewis Waddicor <nemesismk2@gmail.com>
+Li-Yu Yu <aaronyu@google.com>
 Liam Haworth <liam@haworth.id.au>
 Lily Chung <lilithkchung@gmail.com>
 Lingchao Xin <douglarek@gmail.com>
@@ -1657,7 +1721,9 @@ Mark Adams <mark@markadams.me>
 Mark Bucciarelli <mkbucc@gmail.com>
 Mark Dain <mark@markdain.net>
 Mark Glines <mark@glines.org>
+Mark Hansen <markhansen@google.com>
 Mark Harrison <marhar@google.com>
+Mark Jeffery <dandare100@gmail.com>
 Mark Percival <m@mdp.im>
 Mark Pulford <mark@kyne.com.au>
 Mark Rushakoff <mark.rushakoff@gmail.com>
@@ -1686,7 +1752,7 @@ Martin Hoefling <martin.hoefling@gmx.de>
 Martin Kreichgauer <martinkr@google.com>
 Martin Kunc <martinkunc@users.noreply.github.com>
 Martin Lindhe <martin.j.lindhe@gmail.com>
-Martin Möhrmann <moehrmann@google.com> <martisch@uos.de>
+Martin Möhrmann <martin@golang.org> <moehrmann@google.com> <martisch@uos.de>
 Martin Neubauer <m.ne@gmx.net>
 Martin Olsen <github.com@martinolsen.net>
 Martin Olsson <martin@minimum.se>
@@ -1741,6 +1807,7 @@ Matthew Denton <mdenton@skyportsystems.com>
 Matthew Holt <Matthew.Holt+git@gmail.com>
 Matthew Horsnell <matthew.horsnell@gmail.com>
 Matthew Waters <mwwaters@gmail.com>
+Matthias Dötsch <matze@mdoetsch.de>
 Matthias Frei <matthias.frei@inf.ethz.ch>
 Matthieu Hauglustaine <matt.hauglustaine@gmail.com>
 Matthieu Olivier <olivier.matthieu@gmail.com>
@@ -1814,6 +1881,7 @@ Michal Bohuslávek <mbohuslavek@gmail.com>
 Michal Cierniak <cierniak@google.com>
 Michał Derkacz <ziutek@lnet.pl>
 Michal Franc <lam.michal.franc@gmail.com>
+Michal Hruby <michal@axiom.co>
 Michał Łowicki <mlowicki@gmail.com>
 Michal Pristas <michal.pristas@gmail.com>
 Michal Rostecki <mrostecki@suse.de>
@@ -1844,6 +1912,7 @@ Mike Solomon <msolo@gmail.com>
 Mike Strosaker <strosake@us.ibm.com>
 Mike Tsao <mike@sowbug.com>
 Mike Wiacek <mjwiacek@google.com>
+Mikhail Faraponov <11322032+moredure@users.noreply.github.com>
 Mikhail Fesenko <proggga@gmail.com>
 Mikhail Gusarov <dottedmag@dottedmag.net>
 Mikhail Panchenko <m@mihasya.com>
@@ -1870,6 +1939,7 @@ Moritz Fain <moritz@fain.io>
 Moriyoshi Koizumi <mozo@mozo.jp>
 Morten Siebuhr <sbhr@sbhr.dk>
 Môshe van der Sterre <moshevds@gmail.com>
+Mostafa Solati <mostafa.solati@gmail.com>
 Mostyn Bramley-Moore <mostyn@antipode.se>
 Mrunal Patel <mrunalp@gmail.com>
 Muhammad Falak R Wani <falakreyaz@gmail.com>
@@ -1927,6 +1997,7 @@ Nick Miyake <nmiyake@users.noreply.github.com>
 Nick Patavalis <nick.patavalis@gmail.com>
 Nick Petroni <npetroni@cs.umd.edu>
 Nick Robinson <nrobinson13@gmail.com>
+Nick Sherron <nsherron90@gmail.com>
 Nick Smolin <nick27surgut@gmail.com>
 Nicolas BRULEZ <n.brulez@gmail.com>
 Nicolas Kaiser <nikai@nikai.net>
@@ -1956,6 +2027,7 @@ Noah Santschi-Cooney <noah@santschi-cooney.ch>
 Noble Johnson <noblepoly@gmail.com>
 Nodir Turakulov <nodir@google.com>
 Noel Georgi <git@frezbo.com>
+Nooras Saba <saba@golang.org>
 Norberto Lopes <nlopes.ml@gmail.com>
 Norman B. Lancaster <qbradq@gmail.com>
 Nuno Cruces <ncruces@users.noreply.github.com>
@@ -1973,6 +2045,7 @@ Oliver Tan <otan@cockroachlabs.com>
 Oliver Tonnhofer <olt@bogosoft.com>
 Olivier Antoine <olivier.antoine@gmail.com>
 Olivier Duperray <duperray.olivier@gmail.com>
+Olivier Mengué <olivier.mengue@gmail.com>
 Olivier Poitrey <rs@dailymotion.com>
 Olivier Saingre <osaingre@gmail.com>
 Olivier Wulveryck <olivier.wulveryck@gmail.com>
@@ -1982,6 +2055,7 @@ Ori Bernstein <ori@eigenstate.org>
 Ori Rawlings <orirawlings@gmail.com>
 Oryan Moshe <iamoryanmoshe@gmail.com>
 Osamu TONOMORI <osamingo@gmail.com>
+Oscar Söderlund <oscar.soderlund@einride.tech>
 Özgür Kesim <oec-go@kesim.org>
 Pablo Caderno <kaderno@gmail.com>
 Pablo Lalloni <plalloni@gmail.com>
@@ -2014,6 +2088,7 @@ Patrick Pelletier <pp.pelletier@gmail.com>
 Patrick Riley <pfr@google.com>
 Patrick Smith <pat42smith@gmail.com>
 Patrik Lundin <patrik@sigterm.se>
+Patrik Nyblom <pnyb@google.com>
 Paul A Querna <paul.querna@gmail.com>
 Paul Borman <borman@google.com>
 Paul Boyd <boyd.paul2@gmail.com>
@@ -2042,6 +2117,7 @@ Paul Wankadia <junyer@google.com>
 Paulo Casaretto <pcasaretto@gmail.com>
 Paulo Flabiano Smorigo <pfsmorigo@linux.vnet.ibm.com>
 Paulo Gomes <paulo.gomes.uk@gmail.com>
+Pavel Kositsyn <kositsyn.pa@phystech.edu>
 Pavel Paulau <pavel.paulau@gmail.com>
 Pavel Watson <watsonpavel@gmail.com>
 Pavel Zinovkin <pavel.zinovkin@gmail.com>
@@ -2049,6 +2125,7 @@ Pavlo Sumkin <ymkins@gmail.com>
 Pawel Knap <pawelknap88@gmail.com>
 Pawel Szczur <filemon@google.com>
 Paweł Szulik <pawel.szulik@intel.com>
+Pedro Lopez Mareque <pedro.lopez.mareque@gmail.com>
 Pei Xian Chee <luciolas1991@gmail.com>
 Pei-Ming Wu <p408865@gmail.com>
 Pen Tree <appletree2479@outlook.com>
@@ -2164,6 +2241,7 @@ Rhys Hiltner <rhys@justin.tv>
 Ricardo Padilha <ricardospadilha@gmail.com>
 Ricardo Pchevuzinske Katz <ricardo.katz@serpro.gov.br>
 Ricardo Seriani <ricardo.seriani@gmail.com>
+Rich Hong <hong.rich@gmail.com>
 Richard Barnes <rlb@ipv.sx>
 Richard Crowley <r@rcrowley.org>
 Richard Dingwall <rdingwall@gmail.com>
@@ -2179,6 +2257,7 @@ Rick Hudson <rlh@golang.org>
 Rick Sayre <whorfin@gmail.com>
 Rijnard van Tonder <rvantonder@gmail.com>
 Riku Voipio <riku.voipio@linaro.org>
+Riley Avron <ra.git@posteo.net>
 Risto Jaakko Saarelma <rsaarelm@gmail.com>
 Rob Earhart <earhart@google.com>
 Rob Findley <rfindley@google.com>
@@ -2186,8 +2265,10 @@ Rob Norman <rob.norman@infinitycloud.com>
 Rob Phoenix <rob@robphoenix.com>
 Rob Pike <r@golang.org>
 Robert Ayrapetyan <robert.ayrapetyan@gmail.com>
+Robert Burke <rebo@google.com>
 Robert Daniel Kortschak <dan.kortschak@adelaide.edu.au> <dan@kortschak.io>
 Robert Dinu <r@varp.se>
+Robert Engels <rengels@ix.netcom.com>
 Robert Figueiredo <robfig@gmail.com>
 Robert Griesemer <gri@golang.org>
 Robert Hencke <robert.hencke@gmail.com>
@@ -2212,6 +2293,7 @@ Roger Peppe <rogpeppe@gmail.com>
 Rohan Challa <rohan@golang.org>
 Rohan Verma <rohanverma2004@gmail.com>
 Rohith Ravi <entombedvirus@gmail.com>
+Roi Martin <jroi.martin@gmail.com>
 Roland Illig <roland.illig@gmx.de>
 Roland Shoemaker <rolandshoemaker@gmail.com>
 Romain Baugue <romain.baugue@elwinar.com>
@@ -2242,6 +2324,7 @@ Ryan Canty <jrcanty@gmail.com>
 Ryan Dahl <ry@tinyclouds.org>
 Ryan Hitchman <hitchmanr@gmail.com>
 Ryan Kohler <ryankohler@google.com>
+Ryan Leung <rleungx@gmail.com>
 Ryan Lower <rpjlower@gmail.com>
 Ryan Roden-Corrent <ryan@rcorre.net>
 Ryan Seys <ryan@ryanseys.com>
@@ -2275,6 +2358,7 @@ Sami Pönkänen <sami.ponkanen@gmail.com>
 Samuel Kelemen <SCKelemen@users.noreply.github.com>
 Samuel Tan <samueltan@google.com>
 Samuele Pedroni <pedronis@lucediurna.net>
+San Ye <xyesan@gmail.com>
 Sander van Harmelen <sander@vanharmelen.nl>
 Sanjay Menakuru <balasanjay@gmail.com>
 Santhosh Kumar Tekuri <santhosh.tekuri@gmail.com>
@@ -2339,6 +2423,7 @@ Shaba Abhiram <shabarivas.abhiram@gmail.com>
 Shahar Kohanim <skohanim@gmail.com>
 Shailesh Suryawanshi <ss.shailesh28@gmail.com>
 Shamil Garatuev <garatuev@gmail.com>
+Shamim Akhtar <shamim.rhce@gmail.com>
 Shane Hansen <shanemhansen@gmail.com>
 Shang Jian Ding <sding3@ncsu.edu>
 Shaozhen Ding <dsz0111@gmail.com>
@@ -2375,6 +2460,7 @@ Simon Drake <simondrake1990@gmail.com>
 Simon Ferquel <simon.ferquel@docker.com>
 Simon Frei <freisim93@gmail.com>
 Simon Jefford <simon.jefford@gmail.com>
+Simon Law <sfllaw@sfllaw.ca>
 Simon Rawet <simon@rawet.se>
 Simon Rozman <simon@rozman.si>
 Simon Ser <contact@emersion.fr>
@@ -2440,6 +2526,7 @@ Suharsh Sivakumar <suharshs@google.com>
 Sukrit Handa <sukrit.handa@utoronto.ca>
 Sunny <me@darkowlzz.space>
 Suriyaa Sundararuban <suriyaasundararuban@gmail.com>
+Suvaditya Sur <suvaditya.sur@gmail.com>
 Suyash <dextrous93@gmail.com>
 Suzy Mueller <suzmue@golang.org>
 Sven Almgren <sven@tras.se>
@@ -2502,6 +2589,7 @@ Thomas Symborski <thomas.symborski@gmail.com>
 Thomas Wanielista <tomwans@gmail.com>
 Thorben Krueger <thorben.krueger@gmail.com>
 Thordur Bjornsson <thorduri@secnorth.net>
+Tiago Peczenyj <tpeczenyj@weborama.com>
 Tiago Queiroz <contato@tiago.eti.br>
 Tianji Wu <the729@gmail.com>
 Tianon Gravi <admwiggin@gmail.com>
@@ -2636,6 +2724,7 @@ Vladimir Varankin <nek.narqo@gmail.com>
 Vojtech Bocek <vbocek@gmail.com>
 Volker Dobler <dr.volker.dobler@gmail.com>
 Volodymyr Paprotski <vpaprots@ca.ibm.com>
+Vyacheslav Pachkov <slava.pach@gmail.com>
 W. Trevor King <wking@tremily.us>
 Wade Simmons <wade@wades.im>
 Wagner Riffel <wgrriffel@gmail.com>
@@ -2653,6 +2742,7 @@ Wei Guangjing <vcc.163@gmail.com>
 Wei Xiao <wei.xiao@arm.com>
 Wei Xikai <xykwei@gmail.com>
 Weichao Tang <tevic.tt@gmail.com>
+Weilu Jia <optix2000@gmail.com>
 Weixie Cui <cuiweixie@gmail.com> <523516579@qq.com>
 Wembley G. Leach, Jr <wembley.gl@gmail.com>
 Wenlei (Frank) He <wlhe@google.com>
@@ -2722,9 +2812,11 @@ Yuichi Nishiwaki <yuichi.nishiwaki@gmail.com>
 Yuji Yaginuma <yuuji.yaginuma@gmail.com>
 Yuki Ito <mrno110y@gmail.com>
 Yuki OKUSHI <huyuumi.dev@gmail.com>
+Yuki Osaki <yuki.osaki7@gmail.com>
 Yuki Yugui Sonoda <yugui@google.com>
 Yukihiro Nishinaka <6elpinal@gmail.com>
 YunQiang Su <syq@debian.org>
+Yuntao Wang <ytcoode@gmail.com>
 Yury Smolsky <yury@smolsky.by>
 Yusuke Kagiwada <block.rxckin.beats@gmail.com>
 Yuusei Kuwana <kuwana@kumama.org>
@@ -2736,7 +2828,9 @@ Zach Gershman <zachgersh@gmail.com>
 Zach Hoffman <zrhoffman@apache.org>
 Zach Jones <zachj1@gmail.com>
 Zachary Amsden <zach@thundertoken.com>
+Zachary Burkett <zburkett@splitcubestudios.com>
 Zachary Gershman <zgershman@pivotal.io>
+Zaiyang Li <zaiyangli777@gmail.com>
 Zak <zrjknill@gmail.com>
 Zakatell Kanda <hi@zkanda.io>
 Zellyn Hunter <zellyn@squareup.com> <zellyn@gmail.com>
@@ -2745,6 +2839,7 @@ Zhang Boyang <zhangboyang.id@gmail.com>
 Zheng Dayu <davidzheng23@gmail.com>
 Zheng Xu <zheng.xu@arm.com>
 Zhengyu He <hzy@google.com>
+Zhi Zheng <zhi.zheng052@gmail.com>
 Zhongpeng Lin <zplin@uber.com>
 Zhongtao Chen <chenzhongtao@126.com>
 Zhongwei Yao <zhongwei.yao@arm.com>

api/go1.18.txt

@@ -165,8 +165,8 @@ pkg reflect, method (Value) FieldByIndexErr([]int) (Value, error)
 pkg reflect, method (Value) SetIterKey(*MapIter)
 pkg reflect, method (Value) SetIterValue(*MapIter)
 pkg reflect, method (Value) UnsafePointer() unsafe.Pointer
-pkg runtime/debug, method (*BuildInfo) MarshalText() ([]uint8, error)
+pkg runtime/debug, func ParseBuildInfo(string) (*BuildInfo, error)
-pkg runtime/debug, method (*BuildInfo) UnmarshalText([]uint8) error
+pkg runtime/debug, method (*BuildInfo) String() string
 pkg runtime/debug, type BuildInfo struct, GoVersion string
 pkg runtime/debug, type BuildInfo struct, Settings []BuildSetting
 pkg runtime/debug, type BuildSetting struct

codereview.cfg

@@ -1,2 +1,2 @@
-branch: dev.boringcrypto
+branch: dev.boringcrypto.go1.18
 parent-branch: master

doc/go1.18.html

@@ -84,7 +84,7 @@ Do not send CLs removing the interior tags from such phrases.
   <li>
     The new
     <a href="/ref/spec#Predeclared_identifiers">predeclared identifier</a>
-    <code>comparable</code> is an interface the denotes the set of all types which can be
+    <code>comparable</code> is an interface that denotes the set of all types which can be
     compared using <code>==</code> or <code>!=</code>. It may only be used as (or embedded in)
     a type constraint.
   </li>
@@ -135,9 +135,19 @@ Do not send CLs removing the interior tags from such phrases.
       the predeclared functions <code>real</code>, <code>imag</code>, and <code>complex</code>.
       We hope to remove this restriction in Go 1.19.
     </li>
+    <li><!-- https://golang.org/issue/51183 -->
+      The Go compiler currently only supports calling a method <code>m</code> on a value
+      <code>x</code> of type parameter type <code>P</code> if <code>m</code> is explicitly
+      declared by <code>P</code>'s constraint interface.
+      Similarly, method values <code>x.m</code> and method expressions
+      <code>P.m</code> also are only supported if <code>m</code> is explicitly
+      declared by <code>P</code>, even though <code>m</code> might be in the method set
+      of <code>P</code> by virtue of the fact that all types in <code>P</code> implement
+      <code>m</code>. We hope to remove this restriction in Go 1.19.
+    </li>
     <li><!-- https://golang.org/issue/49030 -->
       Embedding a type parameter, or a pointer to a type parameter, as
-      an unnamed field in a struct type is not permitted. Similarly
+      an unnamed field in a struct type is not permitted. Similarly,
       embedding a type parameter in an interface type is not permitted.
       Whether these will ever be permitted is unclear at present.
     </li>
@@ -182,7 +192,7 @@ Do not send CLs removing the interior tags from such phrases.
 
 <p><!-- CL 349595 -->
   Go 1.18 introduces the new <code>GOAMD64</code> environment variable, which selects at compile time
-  a mininum target version of the AMD64 architecture. Allowed values are <code>v1</code>,
+  a minimum target version of the AMD64 architecture. Allowed values are <code>v1</code>,
   <code>v2</code>, <code>v3</code>, or <code>v4</code>. Each higher level requires,
   and takes advantage of, additional processor features. A detailed
   description can be found
@@ -199,6 +209,12 @@ Do not send CLs removing the interior tags from such phrases.
   now supports the <code>c-archive</code> and <code>c-shared</code> build modes.
 </p>
 
+<h3 id="linux">Linux</h3>
+
+<p><!-- golang.org/issue/45964 -->
+  Go 1.18 requires Linux kernel version 2.6.32 or later.
+</p>
+
 <h3 id="windows">Windows</h3>
 
 <p><!-- https://golang.org/issue/49759 -->
@@ -250,6 +266,8 @@ Do not send CLs removing the interior tags from such phrases.
 
 <h3 id="go-command">Go command</h3>
 
+<h4 id="go-get"><code>go</code> <code>get</code></h4>
+
 <p><!-- golang.org/issue/43684 -->
   <code>go</code> <code>get</code> no longer builds or installs packages in
   module-aware mode. <code>go</code> <code>get</code> is now dedicated to
@@ -269,9 +287,25 @@ Do not send CLs removing the interior tags from such phrases.
   and installs packages, as before.
 </p>
 
+<h4 id="go-mod-updates">Automatic <code>go.mod</code> and <code>go.sum</code> updates</h4>
+
+<p><!-- https://go.dev/issue/45551 -->
+  The <code>go</code> <code>mod</code> <code>graph</code>,
+  <code>go</code> <code>mod</code> <code>vendor</code>,
+  <code>go</code> <code>mod</code> <code>verify</code>, and
+  <code>go</code> <code>mod</code> <code>why</code> subcommands
+  no longer automatically update the <code>go.mod</code> and
+  <code>go.sum</code> files.
+  (Those files can be updated explicitly using <code>go</code> <code>get</code>,
+  <code>go</code> <code>mod</code> <code>tidy</code>, or
+  <code>go</code> <code>mod</code> <code>download</code>.)
+</p>
+
+<h4 id="go-version"><code>go</code> <code>version</code></h4>
+
 <p><!-- golang.org/issue/37475 -->
   The <code>go</code> command now embeds version control information in
-  binaries including the currently checked-out revision, commit time, and a
+  binaries. It includes the currently checked-out revision, commit time, and a
   flag indicating whether edited or untracked files are present. Version
   control information is embedded if the <code>go</code> command is invoked in
   a directory within a Git, Mercurial, Fossil, or Bazaar repository, and the
@@ -281,7 +315,7 @@ Do not send CLs removing the interior tags from such phrases.
 </p>
 
 <p><!-- golang.org/issue/37475 -->
-  Additionally, the <code>go</code> command embeds information about the build
+  Additionally, the <code>go</code> command embeds information about the build,
   including build and tool tags (set with <code>-tags</code>), compiler,
   assembler, and linker flags (like <code>-gcflags</code>), whether cgo was
   enabled, and if it was, the values of the cgo environment variables
@@ -303,6 +337,8 @@ Do not send CLs removing the interior tags from such phrases.
   <code>debug/buildinfo</code> package from <code>go</code> 1.18+.
 </p>
 
+<h4 id="go-mod-download"><code>go</code> <code>mod</code> <code>download</code></h4>
+
 <p><!-- https://golang.org/issue/44435 -->
   If the main module's <code>go.mod</code> file
   specifies <a href="/ref/mod#go-mod-file-go"><code>go</code> <code>1.17</code></a>
@@ -316,6 +352,8 @@ Do not send CLs removing the interior tags from such phrases.
   <code>go</code> <code>mod</code> <code>download</code> <code>all</code>.
 </p>
 
+<h4 id="go-mod-vendor"><code>go</code> <code>mod</code> <code>vendor</code></h4>
+
 <p><!-- https://golang.org/issue/47327 -->
   The <code>go</code> <code>mod</code> <code>vendor</code> subcommand now
   supports a <code>-o</code> flag to set the output directory.
@@ -325,14 +363,9 @@ Do not send CLs removing the interior tags from such phrases.
   third-party tools that need to collect package source code.)
 </p>
 
-<p><!-- CL 298612 -->
+<h4 id="go-mod-tidy"><code>go</code> <code>mod</code> <code>tidy</code></h4>
-  The <code>go</code> <code>build</code> command and related commands
-  now support an <code>-asan</code> flag that enables interoperation
-  with C (or C++) code compiled with the address sanitizer (C compiler
-  option <code>-fsanitize=address</code>).
-</p>
 
-<p><!-- https://golang.org/issue/47738 -->
+<p><!-- https://golang.org/issue/47738, CL 344572 -->
   The <code>go</code> <code>mod</code> <code>tidy</code> command now retains
   additional checksums in the <code>go.sum</code> file for modules whose source
   code is needed to verify that each imported package is provided by only one
@@ -342,11 +375,13 @@ Do not send CLs removing the interior tags from such phrases.
   module's <code>go.mod</code> file.
 </p>
 
+<h4 id="go-work"><code>go</code> <code>work</code></h4>
+
 <p><!-- https://golang.org/issue/45713 -->
   The <code>go</code> command now supports a "Workspace" mode. If a
   <code>go.work</code> file is found in the working directory or a
-  parent directory, or one is specified using the <code>-workfile</code>
+  parent directory, or one is specified using the <code>GOWORK</code>
-  flag, it will put the <code>go</code> command into workspace mode.
+  environment variable, it will put the <code>go</code> command into workspace mode.
   In workspace mode, the <code>go.work</code> file will be used to
   determine the set of main modules used as the roots for module
   resolution, instead of using the normally-found <code>go.mod</code>
@@ -355,6 +390,17 @@ Do not send CLs removing the interior tags from such phrases.
   documentation.
 </p>
 
+<h4 id="go-build-asan"><code>go</code> <code>build</code> <code>-asan</code></h4>
+
+<p><!-- CL 298612 -->
+  The <code>go</code> <code>build</code> command and related commands
+  now support an <code>-asan</code> flag that enables interoperation
+  with C (or C++) code compiled with the address sanitizer (C compiler
+  option <code>-fsanitize=address</code>).
+</p>
+
+<h4 id="go-test"><code>go</code> <code>test</code></h4>
+
 <p><!-- CL 251441 -->
   The <code>go</code> command now supports additional command line
   options for the new <a href="#fuzzing">fuzzing support described
@@ -376,7 +422,28 @@ Do not send CLs removing the interior tags from such phrases.
   </ul>
 </p>
 
-<h3 id="gofmt"><code>gofmt</code></h3>
+<h4 id="go-build-lines"><code>//go:build</code> lines</h4>
+
+<p><!-- CL 240611 -->
+Go 1.17 introduced <code>//go:build</code> lines as a more readable way to write build constraints,
+instead of <code>//</code> <code>+build</code> lines.
+As of Go 1.17, <code>gofmt</code> adds <code>//go:build</code> lines
+to match existing <code>+build</code> lines and keeps them in sync,
+while <code>go</code> <code>vet</code> diagnoses when they are out of sync.
+</p>
+
+<p>Since the release of Go 1.18 marks the end of support for Go 1.16,
+all supported versions of Go now understand <code>//go:build</code> lines.
+In Go 1.18, <code>go</code> <code>fix</code> now removes the now-obsolete
+<code>//</code> <code>+build</code> lines in modules declaring
+<code>go</code> <code>1.17</code> or later in their <code>go.mod</code> files.
+</p>
+
+<p>
+For more information, see <a href="https://go.dev/design/draft-gobuild">https://go.dev/design/draft-gobuild</a>.
+</p>
+
+<h3 id="gofmt">Gofmt</h3>
 
 <p><!-- https://golang.org/issue/43566 -->
   <code>gofmt</code> now reads and formats input files concurrently, with a
@@ -384,7 +451,7 @@ Do not send CLs removing the interior tags from such phrases.
   multiple CPUs, <code>gofmt</code> should now be significantly faster.
 </p>
 
-<h3 id="vet"><code>vet</code></h3>
+<h3 id="vet">Vet</h3>
 
 <h4 id="vet-generics">Updates for Generics</h4>
 
@@ -472,7 +539,7 @@ Do not send CLs removing the interior tags from such phrases.
 </p>
 
 <p><!-- CL 298611 -->
-  The new compiler <code>-asan</code> option supports the
+  The new <code>-asan</code> compiler option supports the
   new <code>go</code> command <code>-asan</code> option.
 </p>
 
@@ -502,10 +569,23 @@ Do not send CLs removing the interior tags from such phrases.
 </p>
 
 <p><!-- CL 298610 -->
-  The new linker <code>-asan</code> option supports the
+  The new <code>-asan</code> linker option supports the
   new <code>go</code> command <code>-asan</code> option.
 </p>
 
+<h2 id="bootstrap">Bootstrap</h2>
+
+<p><!-- CL 369914, CL 370274 -->
+When building a Go release from source and <code>GOROOT_BOOTSTRAP</code>
+is not set, previous versions of Go looked for a Go 1.4 or later bootstrap toolchain
+in the directory <code>$HOME/go1.4</code> (<code>%HOMEDRIVE%%HOMEPATH%\go1.4</code> on Windows).
+Go now looks first for <code>$HOME/go1.17</code> or <code>$HOME/sdk/go1.17</code>
+before falling back to <code>$HOME/go1.4</code>.
+We intend for Go 1.19 to require Go 1.17 or later for bootstrap,
+and this change should make the transition smoother.
+For more details, see <a href="https://go.dev/issue/44505">go.dev/issue/44505</a>.
+</p>
+
 <h2 id="library">Core library</h2>
 
 <h3 id="debug/buildinfo">New <code>debug/buildinfo</code> package</h3>
@@ -630,8 +710,8 @@ Do not send CLs removing the interior tags from such phrases.
     </p>
 
     <p><!-- CL 345570 -->
-      The methods <a href="/pkg/bufio#Reader.Reset"><code>Reader.Reset</code></a> and
+      The <a href="/pkg/bufio#Reader.Reset"><code>Reader.Reset</code></a> and
-      <a href="/pkg/bufio#Writer.Reset"><code>Writer.Reset</code></a>
+      <a href="/pkg/bufio#Writer.Reset"><code>Writer.Reset</code></a> methods
       now use the default buffer size when called on objects with a
       <code>nil</code> buffer.
     </p>
@@ -909,6 +989,19 @@ Do not send CLs removing the interior tags from such phrases.
         field.
       </li>
     </ul>
+    <p>
+      The predicates
+      <a href="/pkg/go/types/#AssignableTo"><code>AssignableTo</code></a>,
+      <a href="/pkg/go/types/#ConvertibleTo"><code>ConvertibleTo</code></a>,
+      <a href="/pkg/go/types/#Implements"><code>Implements</code></a>,
+      <a href="/pkg/go/types/#Identical"><code>Identical</code></a>,
+      <a href="/pkg/go/types/#IdenticalIgnoreTags"><code>IdenticalIgnoreTags</code></a>, and
+      <a href="/pkg/go/types/#AssertableTo"><code>AssertableTo</code></a>
+      now also work with arguments that are or contain generalized interfaces, i.e. interfaces
+      that may only be used as type constraints in Go code.
+      Note that the behavior of <code>AssertableTo</code> is undefined if the first argument
+      is a generalized interface.
+    </p>
   </dd>
 </dl>
 
@@ -980,7 +1073,7 @@ Do not send CLs removing the interior tags from such phrases.
 <dl id="os/user"><dt><a href="/pkg/os/user/">os/user</a></dt>
   <dd>
     <p><!-- CL 330753 -->
-      <a href="/pkg/os/user#User.GroupIds"><code>User.GroupIds</code></a>.
+      <a href="/pkg/os/user#User.GroupIds"><code>User.GroupIds</code></a>
       now uses a Go native implementation when cgo is not available.
     </p>
   </dd>
@@ -993,7 +1086,7 @@ Do not send CLs removing the interior tags from such phrases.
       <a href="/pkg/reflect/#Value.SetIterKey"><code>Value.SetIterKey</code></a>
       and <a href="/pkg/reflect/#Value.SetIterValue"><code>Value.SetIterValue</code></a>
       methods set a Value using a map iterator as the source. They are equivalent to
-      <code>Value.Set(iter.Key())</code> and <code>Value.Set(iter.Value())</code> but
+      <code>Value.Set(iter.Key())</code> and <code>Value.Set(iter.Value())</code>, but
       do fewer allocations.
     </p>
 
@@ -1045,7 +1138,7 @@ Do not send CLs removing the interior tags from such phrases.
       The old names will continue to work, but will be deprecated in a
       future Go release.
     </p>
-  </dd>
+  </dd><!-- CL 321889 and CL 345486 are optimizations, no need to mention. -->
 </dl><!-- reflect -->
 
 <dl id="regexp"><dt><a href="/pkg/regexp/">regexp</a></dt>
@@ -1078,6 +1171,16 @@ Do not send CLs removing the interior tags from such phrases.
   </dd>
 </dl><!-- runtime/debug -->
 
+<dl id="runtime/pprof"><dt><a href="/pkg/runtime/pprof/">runtime/pprof</a></dt>
+  <dd>
+    <p><!-- CL 324129 -->
+      The CPU profiler now uses per-thread timers on Linux. This increases the
+      maximum CPU usage that a profile can observe, and reduces some forms of
+      bias.
+    </p>
+  </dd>
+</dl><!-- runtime/pprof -->
+
 <dl id="strconv"><dt><a href="/pkg/strconv/">strconv</a></dt>
   <dd>
     <p><!-- CL 343877 -->
@@ -1147,7 +1250,7 @@ Do not send CLs removing the interior tags from such phrases.
     </p>
 
     <p><!-- CL 355570 -->
-      <a href="/pkg/syscall/?GOOS=freebsd#SysProcAttr.Pdeathsig"><code>SysProcAttr.Pdeathsig</code></a>.
+      <a href="/pkg/syscall/?GOOS=freebsd#SysProcAttr.Pdeathsig"><code>SysProcAttr.Pdeathsig</code></a>
       is now supported in FreeBSD.
     </p>
   </dd>
@@ -1156,7 +1259,7 @@ Do not send CLs removing the interior tags from such phrases.
 <dl id="syscall/js"><dt><a href="/pkg/syscall/js/">syscall/js</a></dt>
   <dd>
     <p><!-- CL 356430 -->
-      <code>Wrapper</code> interface has been removed.
+      The <code>Wrapper</code> interface has been removed.
     </p>
   </dd>
 </dl><!-- syscall/js -->
@@ -1228,7 +1331,7 @@ Do not send CLs removing the interior tags from such phrases.
 <dl id="unicode/utf8"><dt><a href="/pkg/unicode/utf8/">unicode/utf8</a></dt>
   <dd>
     <p><!-- CL 345571 -->
-      The <a href="/pkg/unicode/utf8/#AppendRune"><code>AppendRune</code></a> function appends the UTF-8 new
+      The new <a href="/pkg/unicode/utf8/#AppendRune"><code>AppendRune</code></a> function appends the UTF-8
       encoding of a <code>rune</code> to a <code>[]byte</code>.
     </p>
   </dd>

misc/cgo/testsanitizers/asan_test.go

@@ -63,7 +63,7 @@ func TestASAN(t *testing.T) {
 					// sanitizer library needs a
 					// symbolizer program and can't find it.
 					const noSymbolizer = "external symbolizer"
-					// Check if -asan option can correctly print where the error occured.
+					// Check if -asan option can correctly print where the error occurred.
 					if tc.errorLocation != "" &&
 						!strings.Contains(out, tc.errorLocation) &&
 						!strings.Contains(out, noSymbolizer) &&

misc/reboot/overlaydir_test.go

@@ -6,6 +6,7 @@ package reboot_test
 
 import (
 	"io"
+	"io/fs"
 	"os"
 	"path/filepath"
 	"strings"
@@ -26,10 +27,14 @@ func overlayDir(dstRoot, srcRoot string) error {
 		return err
 	}
 
-	return filepath.Walk(srcRoot, func(srcPath string, info os.FileInfo, err error) error {
+	return filepath.WalkDir(srcRoot, func(srcPath string, entry fs.DirEntry, err error) error {
 		if err != nil || srcPath == srcRoot {
 			return err
 		}
+		if filepath.Base(srcPath) == "testdata" {
+			// We're just building, so no need to copy those.
+			return fs.SkipDir
+		}
 
 		suffix := strings.TrimPrefix(srcPath, srcRoot)
 		for len(suffix) > 0 && suffix[0] == filepath.Separator {
@@ -37,6 +42,7 @@ func overlayDir(dstRoot, srcRoot string) error {
 		}
 		dstPath := filepath.Join(dstRoot, suffix)
 
+		info, err := entry.Info()
 		perm := info.Mode() & os.ModePerm
 		if info.Mode()&os.ModeSymlink != 0 {
 			info, err = os.Stat(srcPath)
@@ -46,14 +52,15 @@ func overlayDir(dstRoot, srcRoot string) error {
 			perm = info.Mode() & os.ModePerm
 		}
 
-		// Always copy directories (don't symlink them).
+		// Always make copies of directories.
 		// If we add a file in the overlay, we don't want to add it in the original.
 		if info.IsDir() {
 			return os.MkdirAll(dstPath, perm|0200)
 		}
 
-		// If the OS supports symlinks, use them instead of copying bytes.
+		// If we can use a hard link, do that instead of copying bytes.
-		if err := os.Symlink(srcPath, dstPath); err == nil {
+		// Go builds don't like symlinks in some cases, such as go:embed.
+		if err := os.Link(srcPath, dstPath); err == nil {
 			return nil
 		}
 

misc/reboot/reboot_test.go

@@ -12,6 +12,7 @@ import (
 	"path/filepath"
 	"runtime"
 	"testing"
+	"time"
 )
 
 func TestRepeatBootstrap(t *testing.T) {
@@ -19,16 +20,14 @@ func TestRepeatBootstrap(t *testing.T) {
 		t.Skipf("skipping test that rebuilds the entire toolchain")
 	}
 
-	goroot, err := os.MkdirTemp("", "reboot-goroot")
+	goroot := t.TempDir()
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer os.RemoveAll(goroot)
 
 	gorootSrc := filepath.Join(goroot, "src")
+	overlayStart := time.Now()
 	if err := overlayDir(gorootSrc, filepath.Join(runtime.GOROOT(), "src")); err != nil {
 		t.Fatal(err)
 	}
+	t.Logf("GOROOT/src overlay set up in %s", time.Since(overlayStart))
 
 	if err := os.WriteFile(filepath.Join(goroot, "VERSION"), []byte(runtime.Version()), 0666); err != nil {
 		t.Fatal(err)

src/builtin/builtin.go

@@ -95,11 +95,11 @@ type rune = int32
 type any = interface{}
 
 // comparable is an interface that is implemented by all comparable types
-// (booleans, numbers, strings, pointers, channels, interfaces,
+// (booleans, numbers, strings, pointers, channels, arrays of comparable types,
-// arrays of comparable types, structs whose fields are all comparable types).
+// structs whose fields are all comparable types).
 // The comparable interface may only be used as a type parameter constraint,
 // not as the type of a variable.
-type comparable comparable
+type comparable interface{ comparable }
 
 // iota is a predeclared identifier representing the untyped integer ordinal
 // number of the current const specification in a (usually parenthesized)

src/bytes/bytes.go

@@ -372,6 +372,8 @@ func genSplit(s, sep []byte, sepSave, n int) [][]byte {
 //   n > 0: at most n subslices; the last subslice will be the unsplit remainder.
 //   n == 0: the result is nil (zero subslices)
 //   n < 0: all subslices
+//
+// To split around the first instance of a separator, see Cut.
 func SplitN(s, sep []byte, n int) [][]byte { return genSplit(s, sep, 0, n) }
 
 // SplitAfterN slices s into subslices after each instance of sep and
@@ -389,6 +391,8 @@ func SplitAfterN(s, sep []byte, n int) [][]byte {
 // the subslices between those separators.
 // If sep is empty, Split splits after each UTF-8 sequence.
 // It is equivalent to SplitN with a count of -1.
+//
+// To split around the first instance of a separator, see Cut.
 func Split(s, sep []byte) [][]byte { return genSplit(s, sep, 0, -1) }
 
 // SplitAfter slices s into all subslices after each instance of sep and

src/cmd/compile/abi-internal.md

@@ -155,7 +155,7 @@ as follows:
 1. Remember I and FP.
 1. If T has zero size, add T to the stack sequence S and return.
 1. Try to register-assign V.
-1. If step 2 failed, reset I and FP to the values from step 1, add T
+1. If step 3 failed, reset I and FP to the values from step 1, add T
    to the stack sequence S, and assign V to this field in S.
 
 Register-assignment of a value V of underlying type T works as follows:

src/cmd/compile/internal/base/base.go

@@ -62,8 +62,9 @@ func Compiling(pkgs []string) bool {
 // at best instrumentation would cause infinite recursion.
 var NoInstrumentPkgs = []string{
 	"runtime/internal/atomic",
-	"runtime/internal/sys",
 	"runtime/internal/math",
+	"runtime/internal/sys",
+	"runtime/internal/syscall",
 	"runtime",
 	"runtime/race",
 	"runtime/msan",

src/cmd/compile/internal/escape/call.go

@@ -238,6 +238,15 @@ func (e *escape) goDeferStmt(n *ir.GoDeferStmt) {
 	fn.SetWrapper(true)
 	fn.Nname.SetType(types.NewSignature(types.LocalPkg, nil, nil, nil, nil))
 	fn.Body = []ir.Node{call}
+	if call, ok := call.(*ir.CallExpr); ok && call.Op() == ir.OCALLFUNC {
+		// If the callee is a named function, link to the original callee.
+		x := call.X
+		if x.Op() == ir.ONAME && x.(*ir.Name).Class == ir.PFUNC {
+			fn.WrappedFunc = call.X.(*ir.Name).Func
+		} else if x.Op() == ir.OMETHEXPR && ir.MethodExprFunc(x).Nname != nil {
+			fn.WrappedFunc = ir.MethodExprName(x).Func
+		}
+	}
 
 	clo := fn.OClosure
 	if n.Op() == ir.OGO {

src/cmd/compile/internal/escape/escape.go

@@ -10,6 +10,7 @@ import (
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/logopt"
+	"cmd/compile/internal/typecheck"
 	"cmd/compile/internal/types"
 )
 
@@ -243,6 +244,9 @@ func (b *batch) flowClosure(k hole, clo *ir.ClosureExpr) {
 		n.SetByval(!loc.addrtaken && !loc.reassigned && n.Type().Size() <= 128)
 		if !n.Byval() {
 			n.SetAddrtaken(true)
+			if n.Sym().Name == typecheck.LocalDictName {
+				base.FatalfAt(n.Pos(), "dictionary variable not captured by value")
+			}
 		}
 
 		if base.Flag.LowerM > 1 {

src/cmd/compile/internal/gc/obj.go

@@ -217,6 +217,10 @@ func dumpGlobalConst(n ir.Node) {
 		if ir.ConstOverflow(v, t) {
 			return
 		}
+	} else {
+		// If the type of the constant is an instantiated generic, we need to emit
+		// that type so the linker knows about it. See issue 51245.
+		_ = reflectdata.TypeLinksym(t)
 	}
 	base.Ctxt.DwarfIntConst(base.Ctxt.Pkgpath, n.Sym().Name, types.TypeSymName(t), ir.IntVal(t, v))
 }
@@ -263,6 +267,10 @@ func addGCLocals() {
 			objw.Global(x, int32(len(x.P)), obj.RODATA|obj.DUPOK)
 			x.Set(obj.AttrStatic, true)
 		}
+		if x := fn.WrapInfo; x != nil && !x.OnList() {
+			objw.Global(x, int32(len(x.P)), obj.RODATA|obj.DUPOK)
+			x.Set(obj.AttrStatic, true)
+		}
 	}
 }
 

src/cmd/compile/internal/importer/iimport.go

@@ -180,6 +180,14 @@ func ImportData(imports map[string]*types2.Package, data, path string) (pkg *typ
 		p.doDecl(localpkg, name)
 	}
 
+	// SetConstraint can't be called if the constraint type is not yet complete.
+	// When type params are created in the 'P' case of (*importReader).obj(),
+	// the associated constraint type may not be complete due to recursion.
+	// Therefore, we defer calling SetConstraint there, and call it here instead
+	// after all types are complete.
+	for _, d := range p.later {
+		d.t.SetConstraint(d.constraint)
+	}
 	// record all referenced packages as imports
 	list := append(([]*types2.Package)(nil), pkgList[1:]...)
 	sort.Sort(byPath(list))
@@ -191,6 +199,11 @@ func ImportData(imports map[string]*types2.Package, data, path string) (pkg *typ
 	return localpkg, nil
 }
 
+type setConstraintArgs struct {
+	t          *types2.TypeParam
+	constraint types2.Type
+}
+
 type iimporter struct {
 	exportVersion int64
 	ipath         string
@@ -206,6 +219,9 @@ type iimporter struct {
 	tparamIndex map[ident]*types2.TypeParam
 
 	interfaceList []*types2.Interface
+
+	// Arguments for calls to SetConstraint that are deferred due to recursive types
+	later []setConstraintArgs
 }
 
 func (p *iimporter) doDecl(pkg *types2.Package, name string) {
@@ -401,7 +417,11 @@ func (r *importReader) obj(name string) {
 			}
 			iface.MarkImplicit()
 		}
-		t.SetConstraint(constraint)
+		// The constraint type may not be complete, if we
+		// are in the middle of a type recursion involving type
+		// constraints. So, we defer SetConstraint until we have
+		// completely set up all types in ImportData.
+		r.p.later = append(r.p.later, setConstraintArgs{t: t, constraint: constraint})
 
 	case 'V':
 		typ := r.typ()

src/cmd/compile/internal/ir/func.go

@@ -133,6 +133,10 @@ type Func struct {
 	// function for go:nowritebarrierrec analysis. Only filled in
 	// if nowritebarrierrecCheck != nil.
 	NWBRCalls *[]SymAndPos
+
+	// For wrapper functions, WrappedFunc point to the original Func.
+	// Currently only used for go/defer wrappers.
+	WrappedFunc *Func
 }
 
 func NewFunc(pos src.XPos) *Func {

src/cmd/compile/internal/ir/sizeof_test.go

@@ -20,7 +20,7 @@ func TestSizeof(t *testing.T) {
 		_32bit uintptr     // size on 32bit platforms
 		_64bit uintptr     // size on 64bit platforms
 	}{
-		{Func{}, 192, 328},
+		{Func{}, 196, 336},
 		{Name{}, 112, 200},
 	}
 

src/cmd/compile/internal/ir/stmt.go

@@ -362,7 +362,7 @@ func NewSendStmt(pos src.XPos, ch, value Node) *SendStmt {
 	return n
 }
 
-// A SwitchStmt is a switch statement: switch Init; Expr { Cases }.
+// A SwitchStmt is a switch statement: switch Init; Tag { Cases }.
 type SwitchStmt struct {
 	miniStmt
 	Tag      Node

src/cmd/compile/internal/noder/expr.go

@@ -114,7 +114,7 @@ func (g *irgen) expr0(typ types2.Type, expr syntax.Expr) ir.Node {
 
 	case *syntax.CallExpr:
 		fun := g.expr(expr.Fun)
-		return Call(pos, g.typ(typ), fun, g.exprs(expr.ArgList), expr.HasDots)
+		return g.callExpr(pos, g.typ(typ), fun, g.exprs(expr.ArgList), expr.HasDots)
 
 	case *syntax.IndexExpr:
 		args := unpackListExpr(expr.Index)
@@ -206,6 +206,53 @@ func (g *irgen) substType(typ *types.Type, tparams *types.Type, targs []ir.Node)
 	return newt
 }
 
+// callExpr creates a call expression (which might be a type conversion, built-in
+// call, or a regular call) and does standard transforms, unless we are in a generic
+// function.
+func (g *irgen) callExpr(pos src.XPos, typ *types.Type, fun ir.Node, args []ir.Node, dots bool) ir.Node {
+	n := ir.NewCallExpr(pos, ir.OCALL, fun, args)
+	n.IsDDD = dots
+	typed(typ, n)
+
+	if fun.Op() == ir.OTYPE {
+		// Actually a type conversion, not a function call.
+		if !g.delayTransform() {
+			return transformConvCall(n)
+		}
+		return n
+	}
+
+	if fun, ok := fun.(*ir.Name); ok && fun.BuiltinOp != 0 {
+		if !g.delayTransform() {
+			return transformBuiltin(n)
+		}
+		return n
+	}
+
+	// Add information, now that we know that fun is actually being called.
+	switch fun := fun.(type) {
+	case *ir.SelectorExpr:
+		if fun.Op() == ir.OMETHVALUE {
+			op := ir.ODOTMETH
+			if fun.X.Type().IsInterface() {
+				op = ir.ODOTINTER
+			}
+			fun.SetOp(op)
+			// Set the type to include the receiver, since that's what
+			// later parts of the compiler expect
+			fun.SetType(fun.Selection.Type)
+		}
+	}
+
+	// A function instantiation (even if fully concrete) shouldn't be
+	// transformed yet, because we need to add the dictionary during the
+	// transformation.
+	if fun.Op() != ir.OFUNCINST && !g.delayTransform() {
+		transformCall(n)
+	}
+	return n
+}
+
 // selectorExpr resolves the choice of ODOT, ODOTPTR, OMETHVALUE (eventually
 // ODOTMETH & ODOTINTER), and OMETHEXPR and deals with embedded fields here rather
 // than in typecheck.go.
@@ -332,13 +379,13 @@ func (g *irgen) exprs(exprs []syntax.Expr) []ir.Node {
 }
 
 func (g *irgen) compLit(typ types2.Type, lit *syntax.CompositeLit) ir.Node {
-	if ptr, ok := types2.StructuralType(typ).(*types2.Pointer); ok {
+	if ptr, ok := types2.CoreType(typ).(*types2.Pointer); ok {
 		n := ir.NewAddrExpr(g.pos(lit), g.compLit(ptr.Elem(), lit))
 		n.SetOp(ir.OPTRLIT)
 		return typed(g.typ(typ), n)
 	}
 
-	_, isStruct := types2.StructuralType(typ).(*types2.Struct)
+	_, isStruct := types2.CoreType(typ).(*types2.Struct)
 
 	exprs := make([]ir.Node, len(lit.ElemList))
 	for i, elem := range lit.ElemList {

src/cmd/compile/internal/noder/helpers.go

@@ -98,95 +98,6 @@ func Binary(pos src.XPos, op ir.Op, typ *types.Type, x, y ir.Node) *ir.BinaryExp
 	}
 }
 
-func Call(pos src.XPos, typ *types.Type, fun ir.Node, args []ir.Node, dots bool) ir.Node {
-	n := ir.NewCallExpr(pos, ir.OCALL, fun, args)
-	n.IsDDD = dots
-
-	if fun.Op() == ir.OTYPE {
-		// Actually a type conversion, not a function call.
-		if !fun.Type().IsInterface() &&
-			(fun.Type().HasTParam() || args[0].Type().HasTParam()) {
-			// For type params, we can transform if fun.Type() is known
-			// to be an interface (in which case a CONVIFACE node will be
-			// inserted). Otherwise, don't typecheck until we actually
-			// know the type.
-			return typed(typ, n)
-		}
-		typed(typ, n)
-		return transformConvCall(n)
-	}
-
-	if fun, ok := fun.(*ir.Name); ok && fun.BuiltinOp != 0 {
-		// For most Builtin ops, we delay doing transformBuiltin if any of the
-		// args have type params, for a variety of reasons:
-		//
-		// OMAKE: transformMake can't choose specific ops OMAKESLICE, etc.
-		//    until arg type is known
-		// OREAL/OIMAG: transformRealImag can't determine type float32/float64
-		//    until arg type known
-		// OAPPEND: transformAppend requires that the arg is a slice
-		// ODELETE: transformDelete requires that the arg is a map
-		// OALIGNOF, OSIZEOF: can be eval'ed to a constant until types known.
-		switch fun.BuiltinOp {
-		case ir.OMAKE, ir.OREAL, ir.OIMAG, ir.OAPPEND, ir.ODELETE, ir.OALIGNOF, ir.OOFFSETOF, ir.OSIZEOF:
-			hasTParam := false
-			for _, arg := range args {
-				if fun.BuiltinOp == ir.OOFFSETOF {
-					// It's the type of left operand of the
-					// selection that matters, not the type of
-					// the field itself (which is irrelevant for
-					// offsetof).
-					arg = arg.(*ir.SelectorExpr).X
-				}
-				if arg.Type().HasTParam() {
-					hasTParam = true
-					break
-				}
-			}
-			if hasTParam {
-				return typed(typ, n)
-			}
-		}
-
-		typed(typ, n)
-		return transformBuiltin(n)
-	}
-
-	// Add information, now that we know that fun is actually being called.
-	switch fun := fun.(type) {
-	case *ir.SelectorExpr:
-		if fun.Op() == ir.OMETHVALUE {
-			op := ir.ODOTMETH
-			if fun.X.Type().IsInterface() {
-				op = ir.ODOTINTER
-			}
-			fun.SetOp(op)
-			// Set the type to include the receiver, since that's what
-			// later parts of the compiler expect
-			fun.SetType(fun.Selection.Type)
-		}
-	}
-
-	if fun.Type().HasTParam() || fun.Op() == ir.OXDOT || fun.Op() == ir.OFUNCINST {
-		// If the fun arg is or has a type param, we can't do all the
-		// transformations, since we may not have needed properties yet
-		// (e.g. number of return values, etc). The same applies if a fun
-		// which is an XDOT could not be transformed yet because of a generic
-		// type in the X of the selector expression.
-		//
-		// A function instantiation (even if fully concrete) shouldn't be
-		// transformed yet, because we need to add the dictionary during the
-		// transformation.
-		return typed(typ, n)
-	}
-
-	// If no type params, do the normal call transformations. This
-	// will convert OCALL to OCALLFUNC.
-	typed(typ, n)
-	transformCall(n)
-	return n
-}
-
 func Compare(pos src.XPos, typ *types.Type, op ir.Op, x, y ir.Node) *ir.BinaryExpr {
 	n := ir.NewBinaryExpr(pos, op, x, y)
 	typed(typ, n)

src/cmd/compile/internal/noder/stencil.go

@@ -410,7 +410,8 @@ func (g *genInst) buildClosure(outer *ir.Func, x ir.Node) ir.Node {
 	fn, formalParams, formalResults := startClosure(pos, outer, typ)
 
 	// This is the dictionary we want to use.
-	// It may be a constant, or it may be a dictionary acquired from the outer function's dictionary.
+	// It may be a constant, it may be the outer functions's dictionary, or it may be
+	// a subdictionary acquired from the outer function's dictionary.
 	// For the latter, dictVar is a variable in the outer function's scope, set to the subdictionary
 	// read from the outer function's dictionary.
 	var dictVar *ir.Name
@@ -640,6 +641,11 @@ func (g *genInst) getInstantiation(nameNode *ir.Name, shapes []*types.Type, isMe
 		// over any pointer)
 		recvType := nameNode.Type().Recv().Type
 		recvType = deref(recvType)
+		if recvType.IsFullyInstantiated() {
+			// Get the type of the base generic type, so we get
+			// its original typeparams.
+			recvType = recvType.OrigSym().Def.(*ir.Name).Type()
+		}
 		tparams = recvType.RParams()
 	} else {
 		fields := nameNode.Type().TParams().Fields().Slice()
@@ -656,11 +662,9 @@ func (g *genInst) getInstantiation(nameNode *ir.Name, shapes []*types.Type, isMe
 	s1 := make([]*types.Type, len(shapes))
 	for i, t := range shapes {
 		var tparam *types.Type
-		if tparams[i].Kind() == types.TTYPEPARAM {
+		// Shapes are grouped differently for structural types, so we
-			// Shapes are grouped differently for structural types, so we
+		// pass the type param to Shapify(), so we can distinguish.
-			// pass the type param to Shapify(), so we can distinguish.
+		tparam = tparams[i]
-			tparam = tparams[i]
-		}
 		if !t.IsShape() {
 			s1[i] = typecheck.Shapify(t, i, tparam)
 		} else {
@@ -1055,8 +1059,6 @@ func (subst *subster) node(n ir.Node) ir.Node {
 				// Transform the conversion, now that we know the
 				// type argument.
 				m = transformConvCall(call)
-				// CONVIFACE transformation was already done in noder2
-				assert(m.Op() != ir.OCONVIFACE)
 
 			case ir.OMETHVALUE, ir.OMETHEXPR:
 				// Redo the transformation of OXDOT, now that we
@@ -1076,14 +1078,7 @@ func (subst *subster) node(n ir.Node) ir.Node {
 			case ir.ONAME:
 				name := call.X.Name()
 				if name.BuiltinOp != ir.OXXX {
-					switch name.BuiltinOp {
+					m = transformBuiltin(call)
-					case ir.OMAKE, ir.OREAL, ir.OIMAG, ir.OAPPEND, ir.ODELETE, ir.OALIGNOF, ir.OOFFSETOF, ir.OSIZEOF:
-						// Transform these builtins now that we
-						// know the type of the args.
-						m = transformBuiltin(call)
-					default:
-						base.FatalfAt(call.Pos(), "Unexpected builtin op")
-					}
 				} else {
 					// This is the case of a function value that was a
 					// type parameter (implied to be a function via a
@@ -1154,6 +1149,7 @@ func (subst *subster) node(n ir.Node) ir.Node {
 			newfn.Dcl = append(newfn.Dcl, ldict)
 			as := ir.NewAssignStmt(x.Pos(), ldict, cdict)
 			as.SetTypecheck(1)
+			ldict.Defn = as
 			newfn.Body.Append(as)
 
 			// Create inst info for the instantiated closure. The dict
@@ -1183,6 +1179,26 @@ func (subst *subster) node(n ir.Node) ir.Node {
 			subst.g.newInsts = append(subst.g.newInsts, m.(*ir.ClosureExpr).Func)
 			m.(*ir.ClosureExpr).SetInit(subst.list(x.Init()))
 
+		case ir.OSWITCH:
+			m := m.(*ir.SwitchStmt)
+			if m.Tag != nil && m.Tag.Op() == ir.OTYPESW {
+				break // Nothing to do here for type switches.
+			}
+			if m.Tag != nil && !m.Tag.Type().IsInterface() && m.Tag.Type().HasShape() {
+				// To implement a switch on a value that is or has a type parameter, we first convert
+				// that thing we're switching on to an interface{}.
+				m.Tag = assignconvfn(m.Tag, types.Types[types.TINTER])
+			}
+			for _, c := range m.Cases {
+				for i, x := range c.List {
+					// If we have a case that is or has a type parameter, convert that case
+					// to an interface{}.
+					if !x.Type().IsInterface() && x.Type().HasShape() {
+						c.List[i] = assignconvfn(x, types.Types[types.TINTER])
+					}
+				}
+			}
+
 		}
 		return m
 	}

src/cmd/compile/internal/noder/transform.go

@@ -242,7 +242,7 @@ func transformCompare(n *ir.BinaryExpr) {
 			aop, _ := typecheck.Assignop(rt, lt)
 			if aop != ir.OXXX {
 				types.CalcSize(rt)
-				if rt.HasTParam() || rt.IsInterface() == lt.IsInterface() || rt.Size() >= 1<<16 {
+				if rt.HasShape() || rt.IsInterface() == lt.IsInterface() || rt.Size() >= 1<<16 {
 					r = ir.NewConvExpr(base.Pos, aop, lt, r)
 					r.SetTypecheck(1)
 				}

src/cmd/compile/internal/noder/writer.go

@@ -1338,10 +1338,10 @@ func (w *writer) compLit(lit *syntax.CompositeLit) {
 	w.typ(tv.Type)
 
 	typ := tv.Type
-	if ptr, ok := types2.StructuralType(typ).(*types2.Pointer); ok {
+	if ptr, ok := types2.CoreType(typ).(*types2.Pointer); ok {
 		typ = ptr.Elem()
 	}
-	str, isStruct := types2.StructuralType(typ).(*types2.Struct)
+	str, isStruct := types2.CoreType(typ).(*types2.Struct)
 
 	w.len(len(lit.ElemList))
 	for i, elem := range lit.ElemList {

src/cmd/compile/internal/reflectdata/reflect.go

@@ -1457,7 +1457,7 @@ func WriteBasicTypes() {
 
 type typeAndStr struct {
 	t       *types.Type
-	short   string // "short" here means NameString
+	short   string // "short" here means TypeSymName
 	regular string
 }
 

src/cmd/compile/internal/ssa/gen/RISCV64.rules

@@ -256,7 +256,7 @@
 (Leq64F ...) => (FLED ...)
 (Leq32F ...) => (FLES ...)
 
-(EqPtr x y) => (SEQZ (SUB <x.Type> x y))
+(EqPtr x y) => (SEQZ (SUB <typ.Uintptr> x y))
 (Eq64  x y) => (SEQZ (SUB <x.Type> x y))
 (Eq32  x y) => (SEQZ (SUB <x.Type> (ZeroExt32to64 x) (ZeroExt32to64 y)))
 (Eq16  x y) => (SEQZ (SUB <x.Type> (ZeroExt16to64 x) (ZeroExt16to64 y)))
@@ -264,7 +264,7 @@
 (Eq64F ...) => (FEQD ...)
 (Eq32F ...) => (FEQS ...)
 
-(NeqPtr x y) => (SNEZ (SUB <x.Type> x y))
+(NeqPtr x y) => (SNEZ (SUB <typ.Uintptr> x y))
 (Neq64  x y) => (SNEZ (SUB <x.Type> x y))
 (Neq32  x y) => (SNEZ (SUB <x.Type> (ZeroExt32to64 x) (ZeroExt32to64 y)))
 (Neq16  x y) => (SNEZ (SUB <x.Type> (ZeroExt16to64 x) (ZeroExt16to64 y)))

src/cmd/compile/internal/ssa/poset.go

@@ -906,7 +906,7 @@ func (po *poset) Ordered(n1, n2 *Value) bool {
 	return i1 != i2 && po.reaches(i1, i2, true)
 }
 
-// Ordered reports whether n1<=n2. It returns false either when it is
+// OrderedOrEqual reports whether n1<=n2. It returns false either when it is
 // certain that n1<=n2 is false, or if there is not enough information
 // to tell.
 // Complexity is O(n).

src/cmd/compile/internal/ssa/rewriteRISCV64.go

@@ -1124,13 +1124,14 @@ func rewriteValueRISCV64_OpEqPtr(v *Value) bool {
 	v_1 := v.Args[1]
 	v_0 := v.Args[0]
 	b := v.Block
+	typ := &b.Func.Config.Types
 	// match: (EqPtr x y)
-	// result: (SEQZ (SUB <x.Type> x y))
+	// result: (SEQZ (SUB <typ.Uintptr> x y))
 	for {
 		x := v_0
 		y := v_1
 		v.reset(OpRISCV64SEQZ)
-		v0 := b.NewValue0(v.Pos, OpRISCV64SUB, x.Type)
+		v0 := b.NewValue0(v.Pos, OpRISCV64SUB, typ.Uintptr)
 		v0.AddArg2(x, y)
 		v.AddArg(v0)
 		return true
@@ -2673,13 +2674,14 @@ func rewriteValueRISCV64_OpNeqPtr(v *Value) bool {
 	v_1 := v.Args[1]
 	v_0 := v.Args[0]
 	b := v.Block
+	typ := &b.Func.Config.Types
 	// match: (NeqPtr x y)
-	// result: (SNEZ (SUB <x.Type> x y))
+	// result: (SNEZ (SUB <typ.Uintptr> x y))
 	for {
 		x := v_0
 		y := v_1
 		v.reset(OpRISCV64SNEZ)
-		v0 := b.NewValue0(v.Pos, OpRISCV64SUB, x.Type)
+		v0 := b.NewValue0(v.Pos, OpRISCV64SUB, typ.Uintptr)
 		v0.AddArg2(x, y)
 		v.AddArg(v0)
 		return true

src/cmd/compile/internal/ssagen/ssa.go

@@ -6768,6 +6768,34 @@ func EmitArgInfo(f *ir.Func, abiInfo *abi.ABIParamResultInfo) *obj.LSym {
 	return x
 }
 
+// for wrapper, emit info of wrapped function.
+func emitWrappedFuncInfo(e *ssafn, pp *objw.Progs) {
+	if base.Ctxt.Flag_linkshared {
+		// Relative reference (SymPtrOff) to another shared object doesn't work.
+		// Unfortunate.
+		return
+	}
+
+	wfn := e.curfn.WrappedFunc
+	if wfn == nil {
+		return
+	}
+
+	wsym := wfn.Linksym()
+	x := base.Ctxt.LookupInit(fmt.Sprintf("%s.wrapinfo", wsym.Name), func(x *obj.LSym) {
+		objw.SymPtrOff(x, 0, wsym)
+		x.Set(obj.AttrContentAddressable, true)
+	})
+	e.curfn.LSym.Func().WrapInfo = x
+
+	// Emit a funcdata pointing at the wrap info data.
+	p := pp.Prog(obj.AFUNCDATA)
+	p.From.SetConst(objabi.FUNCDATA_WrapInfo)
+	p.To.Type = obj.TYPE_MEM
+	p.To.Name = obj.NAME_EXTERN
+	p.To.Sym = x
+}
+
 // genssa appends entries to pp for each instruction in f.
 func genssa(f *ssa.Func, pp *objw.Progs) {
 	var s State
@@ -6790,6 +6818,8 @@ func genssa(f *ssa.Func, pp *objw.Progs) {
 		p.To.Sym = openDeferInfo
 	}
 
+	emitWrappedFuncInfo(e, pp)
+
 	// Remember where each block starts.
 	s.bstart = make([]*obj.Prog, f.NumBlocks())
 	s.pp = pp

src/cmd/compile/internal/test/testdata/ptrsort.go

@@ -6,7 +6,7 @@ package main
 import (
 	"fmt"
 
-	"./mysort"
+	"cmd/compile/internal/test/testdata/mysort"
 )
 
 type MyString struct {

src/cmd/compile/internal/typecheck/iexport.go

@@ -1851,7 +1851,10 @@ func (w *exportWriter) expr(n ir.Node) {
 		n := n.(*ir.ClosureExpr)
 		w.op(ir.OCLOSURE)
 		w.pos(n.Pos())
+		old := w.currPkg
+		w.setPkg(n.Type().Pkg(), true)
 		w.signature(n.Type())
+		w.setPkg(old, true)
 
 		// Write out id for the Outer of each conditional variable. The
 		// conditional variable itself for this closure will be re-created

src/cmd/compile/internal/typecheck/iimport.go

@@ -354,15 +354,18 @@ func (r *importReader) doDecl(sym *types.Sym) *ir.Name {
 		// declaration before recursing.
 		n := importtype(pos, sym)
 		t := n.Type()
+
+		// Because of recursion, we need to defer width calculations and
+		// instantiations on intermediate types until the top-level type is
+		// fully constructed. Note that we can have recursion via type
+		// constraints.
+		types.DeferCheckSize()
+		deferDoInst()
 		if tag == 'U' {
 			rparams := r.typeList()
 			t.SetRParams(rparams)
 		}
 
-		// We also need to defer width calculations until
-		// after the underlying type has been assigned.
-		types.DeferCheckSize()
-		deferDoInst()
 		underlying := r.typ()
 		t.SetUnderlying(underlying)
 
@@ -1371,7 +1374,9 @@ func (r *importReader) node() ir.Node {
 	case ir.OCLOSURE:
 		//println("Importing CLOSURE")
 		pos := r.pos()
+		r.setPkg()
 		typ := r.signature(nil, nil)
+		r.setPkg()
 
 		// All the remaining code below is similar to (*noder).funcLit(), but
 		// with Dcls and ClosureVars lists already set up

src/cmd/compile/internal/typecheck/subr.go

@@ -1424,6 +1424,68 @@ func genericTypeName(sym *types.Sym) string {
 	return sym.Name[0:strings.Index(sym.Name, "[")]
 }
 
+// getShapes appends the list of the shape types that are used within type t to
+// listp. The type traversal is simplified for two reasons: (1) we can always stop a
+// type traversal when t.HasShape() is false; and (2) shape types can't appear inside
+// a named type, except for the type args of a generic type. So, the traversal will
+// always stop before we have to deal with recursive types.
+func getShapes(t *types.Type, listp *[]*types.Type) {
+	if !t.HasShape() {
+		return
+	}
+	if t.IsShape() {
+		*listp = append(*listp, t)
+		return
+	}
+
+	if t.Sym() != nil {
+		// A named type can't have shapes in it, except for type args of a
+		// generic type. We will have to deal with this differently once we
+		// alloc local types in generic functions (#47631).
+		for _, rparam := range t.RParams() {
+			getShapes(rparam, listp)
+		}
+		return
+	}
+
+	switch t.Kind() {
+	case types.TARRAY, types.TPTR, types.TSLICE, types.TCHAN:
+		getShapes(t.Elem(), listp)
+
+	case types.TSTRUCT:
+		for _, f := range t.FieldSlice() {
+			getShapes(f.Type, listp)
+		}
+
+	case types.TFUNC:
+		for _, f := range t.Recvs().FieldSlice() {
+			getShapes(f.Type, listp)
+		}
+		for _, f := range t.Params().FieldSlice() {
+			getShapes(f.Type, listp)
+		}
+		for _, f := range t.Results().FieldSlice() {
+			getShapes(f.Type, listp)
+		}
+		for _, f := range t.TParams().FieldSlice() {
+			getShapes(f.Type, listp)
+		}
+
+	case types.TINTER:
+		for _, f := range t.Methods().Slice() {
+			getShapes(f.Type, listp)
+		}
+
+	case types.TMAP:
+		getShapes(t.Key(), listp)
+		getShapes(t.Elem(), listp)
+
+	default:
+		panic(fmt.Sprintf("Bad type in getShapes: %v", t.Kind()))
+	}
+
+}
+
 // Shapify takes a concrete type and a type param index, and returns a GCshape type that can
 // be used in place of the input type and still generate identical code.
 // No methods are added - all methods calls directly on a shape should
@@ -1432,9 +1494,9 @@ func genericTypeName(sym *types.Sym) string {
 // For now, we only consider two types to have the same shape, if they have exactly
 // the same underlying type or they are both pointer types.
 //
-//  tparam is the associated typeparam. If there is a structural type for
+//  tparam is the associated typeparam - it must be TTYPEPARAM type. If there is a
-//  the associated type param (not common), then a pointer type t is mapped to its
+//  structural type for the associated type param (not common), then a pointer type t
-//  underlying type, rather than being merged with other pointers.
+//  is mapped to its underlying type, rather than being merged with other pointers.
 //
 //  Shape types are also distinguished by the index of the type in a type param/arg
 //  list. We need to do this so we can distinguish and substitute properly for two
@@ -1442,6 +1504,30 @@ func genericTypeName(sym *types.Sym) string {
 //  instantiation.
 func Shapify(t *types.Type, index int, tparam *types.Type) *types.Type {
 	assert(!t.IsShape())
+	if t.HasShape() {
+		// We are sometimes dealing with types from a shape instantiation
+		// that were constructed from existing shape types, so t may
+		// sometimes have shape types inside it. In that case, we find all
+		// those shape types with getShapes() and replace them with their
+		// underlying type.
+		//
+		// If we don't do this, we may create extra unneeded shape types that
+		// have these other shape types embedded in them. This may lead to
+		// generating extra shape instantiations, and a mismatch between the
+		// instantiations that we used in generating dictionaries and the
+		// instantations that are actually called. (#51303).
+		list := []*types.Type{}
+		getShapes(t, &list)
+		list2 := make([]*types.Type, len(list))
+		for i, shape := range list {
+			list2[i] = shape.Underlying()
+		}
+		ts := Tsubster{
+			Tparams: list,
+			Targs:   list2,
+		}
+		t = ts.Typ(t)
+	}
 	// Map all types with the same underlying type to the same shape.
 	u := t.Underlying()
 

src/cmd/compile/internal/types/fmt.go

@@ -72,6 +72,7 @@ const (
 	fmtDebug
 	fmtTypeID
 	fmtTypeIDName
+	fmtTypeIDHash
 )
 
 // Sym
@@ -144,10 +145,21 @@ func symfmt(b *bytes.Buffer, s *Sym, verb rune, mode fmtMode) {
 	if q := pkgqual(s.Pkg, verb, mode); q != "" {
 		b.WriteString(q)
 		b.WriteByte('.')
-		if mode == fmtTypeIDName {
+		switch mode {
+		case fmtTypeIDName:
 			// If name is a generic instantiation, it might have local package placeholders
 			// in it. Replace those placeholders with the package name. See issue 49547.
 			name = strings.Replace(name, LocalPkg.Prefix, q, -1)
+		case fmtTypeIDHash:
+			// If name is a generic instantiation, don't hash the instantiating types.
+			// This isn't great, but it is safe. If we hash the instantiating types, then
+			// we need to make sure they have just the package name. At this point, they
+			// either have "", or the whole package path, and it is hard to reconcile
+			// the two without depending on -p (which we might do someday).
+			// See issue 51250.
+			if i := strings.Index(name, "["); i >= 0 {
+				name = name[:i]
+			}
 		}
 	}
 	b.WriteString(name)
@@ -173,7 +185,7 @@ func pkgqual(pkg *Pkg, verb rune, mode fmtMode) string {
 		case fmtDebug:
 			return pkg.Name
 
-		case fmtTypeIDName:
+		case fmtTypeIDName, fmtTypeIDHash:
 			// dcommontype, typehash
 			return pkg.Name
 
@@ -331,7 +343,7 @@ func tconv2(b *bytes.Buffer, t *Type, verb rune, mode fmtMode, visited map[*Type
 	if t == AnyType || t == ByteType || t == RuneType {
 		// in %-T mode collapse predeclared aliases with their originals.
 		switch mode {
-		case fmtTypeIDName, fmtTypeID:
+		case fmtTypeIDName, fmtTypeIDHash, fmtTypeID:
 			t = Types[t.Kind()]
 		default:
 			sconv2(b, t.Sym(), 'S', mode)
@@ -422,7 +434,7 @@ func tconv2(b *bytes.Buffer, t *Type, verb rune, mode fmtMode, visited map[*Type
 	case TPTR:
 		b.WriteByte('*')
 		switch mode {
-		case fmtTypeID, fmtTypeIDName:
+		case fmtTypeID, fmtTypeIDName, fmtTypeIDHash:
 			if verb == 'S' {
 				tconv2(b, t.Elem(), 'S', mode, visited)
 				return
@@ -484,7 +496,7 @@ func tconv2(b *bytes.Buffer, t *Type, verb rune, mode fmtMode, visited map[*Type
 			case IsExported(f.Sym.Name):
 				sconv2(b, f.Sym, 'S', mode)
 			default:
-				if mode != fmtTypeIDName {
+				if mode != fmtTypeIDName && mode != fmtTypeIDHash {
 					mode = fmtTypeID
 				}
 				sconv2(b, f.Sym, 'v', mode)
@@ -554,7 +566,7 @@ func tconv2(b *bytes.Buffer, t *Type, verb rune, mode fmtMode, visited map[*Type
 			b.WriteByte(byte(open))
 			fieldVerb := 'v'
 			switch mode {
-			case fmtTypeID, fmtTypeIDName, fmtGo:
+			case fmtTypeID, fmtTypeIDName, fmtTypeIDHash, fmtGo:
 				// no argument names on function signature, and no "noescape"/"nosplit" tags
 				fieldVerb = 'S'
 			}
@@ -657,7 +669,7 @@ func fldconv(b *bytes.Buffer, f *Field, verb rune, mode fmtMode, visited map[*Ty
 
 				// Compute tsym, the symbol that would normally be used as
 				// the field name when embedding f.Type.
-				// TODO(mdempsky): Check for other occurences of this logic
+				// TODO(mdempsky): Check for other occurrences of this logic
 				// and deduplicate.
 				typ := f.Type
 				if typ.IsPtr() {
@@ -688,7 +700,7 @@ func fldconv(b *bytes.Buffer, f *Field, verb rune, mode fmtMode, visited map[*Ty
 				if name == ".F" {
 					name = "F" // Hack for toolstash -cmp.
 				}
-				if !IsExported(name) && mode != fmtTypeIDName {
+				if !IsExported(name) && mode != fmtTypeIDName && mode != fmtTypeIDHash {
 					name = sconv(s, 0, mode) // qualify non-exported names (used on structs, not on funarg)
 				}
 			} else {
@@ -756,7 +768,7 @@ func FmtConst(v constant.Value, sharp bool) string {
 
 // TypeHash computes a hash value for type t to use in type switch statements.
 func TypeHash(t *Type) uint32 {
-	p := t.NameString()
+	p := tconv(t, 0, fmtTypeIDHash)
 
 	// Using MD5 is overkill, but reduces accidental collisions.
 	h := md5.Sum([]byte(p))

src/cmd/compile/internal/types2/api.go

@@ -204,12 +204,12 @@ type Info struct {
 	// qualified identifiers are collected in the Uses map.
 	Types map[syntax.Expr]TypeAndValue
 
-	// Instances maps identifiers denoting parameterized types or functions to
+	// Instances maps identifiers denoting generic types or functions to their
-	// their type arguments and instantiated type.
+	// type arguments and instantiated type.
 	//
 	// For example, Instances will map the identifier for 'T' in the type
 	// instantiation T[int, string] to the type arguments [int, string] and
-	// resulting instantiated *Named type. Given a parameterized function
+	// resulting instantiated *Named type. Given a generic function
 	// func F[A any](A), Instances will map the identifier for 'F' in the call
 	// expression F(int(1)) to the inferred type arguments [int], and resulting
 	// instantiated *Signature.
@@ -421,25 +421,45 @@ func (conf *Config) Check(path string, files []*syntax.File, info *Info) (*Packa
 }
 
 // AssertableTo reports whether a value of type V can be asserted to have type T.
+//
+// The behavior of AssertableTo is undefined in two cases:
+//  - if V is a generalized interface; i.e., an interface that may only be used
+//    as a type constraint in Go code
+//  - if T is an uninstantiated generic type
 func AssertableTo(V *Interface, T Type) bool {
-	m, _ := (*Checker)(nil).assertableTo(V, T)
+	// Checker.newAssertableTo suppresses errors for invalid types, so we need special
-	return m == nil
+	// handling here.
+	if T.Underlying() == Typ[Invalid] {
+		return false
+	}
+	return (*Checker)(nil).newAssertableTo(V, T) == nil
 }
 
-// AssignableTo reports whether a value of type V is assignable to a variable of type T.
+// AssignableTo reports whether a value of type V is assignable to a variable
+// of type T.
+//
+// The behavior of AssignableTo is undefined if V or T is an uninstantiated
+// generic type.
 func AssignableTo(V, T Type) bool {
 	x := operand{mode: value, typ: V}
 	ok, _ := x.assignableTo(nil, T, nil) // check not needed for non-constant x
 	return ok
 }
 
-// ConvertibleTo reports whether a value of type V is convertible to a value of type T.
+// ConvertibleTo reports whether a value of type V is convertible to a value of
+// type T.
+//
+// The behavior of ConvertibleTo is undefined if V or T is an uninstantiated
+// generic type.
 func ConvertibleTo(V, T Type) bool {
 	x := operand{mode: value, typ: V}
 	return x.convertibleTo(nil, T, nil) // check not needed for non-constant x
 }
 
 // Implements reports whether type V implements interface T.
+//
+// The behavior of Implements is undefined if V is an uninstantiated generic
+// type.
 func Implements(V Type, T *Interface) bool {
 	if T.Empty() {
 		// All types (even Typ[Invalid]) implement the empty interface.

src/cmd/compile/internal/types2/api_test.go

@@ -12,6 +12,7 @@ import (
 	"internal/testenv"
 	"reflect"
 	"regexp"
+	"sort"
 	"strings"
 	"testing"
 
@@ -403,69 +404,61 @@ func TestTypesInfo(t *testing.T) {
 }
 
 func TestInstanceInfo(t *testing.T) {
-	var tests = []struct {
+	const lib = `package lib
-		src   string
+
+func F[P any](P) {}
+
+type T[P any] []P
+`
+
+	type testInst struct {
 		name  string
 		targs []string
 		typ   string
+	}
+
+	var tests = []struct {
+		src       string
+		instances []testInst // recorded instances in source order
 	}{
 		{`package p0; func f[T any](T) {}; func _() { f(42) }`,
-			`f`,
+			[]testInst{{`f`, []string{`int`}, `func(int)`}},
-			[]string{`int`},
-			`func(int)`,
 		},
 		{`package p1; func f[T any](T) T { panic(0) }; func _() { f('@') }`,
-			`f`,
+			[]testInst{{`f`, []string{`rune`}, `func(rune) rune`}},
-			[]string{`rune`},
-			`func(rune) rune`,
 		},
 		{`package p2; func f[T any](...T) T { panic(0) }; func _() { f(0i) }`,
-			`f`,
+			[]testInst{{`f`, []string{`complex128`}, `func(...complex128) complex128`}},
-			[]string{`complex128`},
-			`func(...complex128) complex128`,
 		},
 		{`package p3; func f[A, B, C any](A, *B, []C) {}; func _() { f(1.2, new(string), []byte{}) }`,
-			`f`,
+			[]testInst{{`f`, []string{`float64`, `string`, `byte`}, `func(float64, *string, []byte)`}},
-			[]string{`float64`, `string`, `byte`},
-			`func(float64, *string, []byte)`,
 		},
 		{`package p4; func f[A, B any](A, *B, ...[]B) {}; func _() { f(1.2, new(byte)) }`,
-			`f`,
+			[]testInst{{`f`, []string{`float64`, `byte`}, `func(float64, *byte, ...[]byte)`}},
-			[]string{`float64`, `byte`},
-			`func(float64, *byte, ...[]byte)`,
 		},
-
 		// we don't know how to translate these but we can type-check them
 		{`package q0; type T struct{}; func (T) m[P any](P) {}; func _(x T) { x.m(42) }`,
-			`m`,
+			[]testInst{{`m`, []string{`int`}, `func(int)`}},
-			[]string{`int`},
-			`func(int)`,
 		},
 		{`package q1; type T struct{}; func (T) m[P any](P) P { panic(0) }; func _(x T) { x.m(42) }`,
-			`m`,
+			[]testInst{{`m`, []string{`int`}, `func(int) int`}},
-			[]string{`int`},
-			`func(int) int`,
 		},
 		{`package q2; type T struct{}; func (T) m[P any](...P) P { panic(0) }; func _(x T) { x.m(42) }`,
-			`m`,
+			[]testInst{{`m`, []string{`int`}, `func(...int) int`}},
-			[]string{`int`},
-			`func(...int) int`,
 		},
 		{`package q3; type T struct{}; func (T) m[A, B, C any](A, *B, []C) {}; func _(x T) { x.m(1.2, new(string), []byte{}) }`,
-			`m`,
+			[]testInst{{`m`, []string{`float64`, `string`, `byte`}, `func(float64, *string, []byte)`}},
-			[]string{`float64`, `string`, `byte`},
-			`func(float64, *string, []byte)`,
 		},
 		{`package q4; type T struct{}; func (T) m[A, B any](A, *B, ...[]B) {}; func _(x T) { x.m(1.2, new(byte)) }`,
-			`m`,
+			[]testInst{{`m`, []string{`float64`, `byte`}, `func(float64, *byte, ...[]byte)`}},
-			[]string{`float64`, `byte`},
-			`func(float64, *byte, ...[]byte)`,
 		},
 
-		{`package r0; type T[P any] struct{}; func (_ T[P]) m[Q any](Q) {}; func _[P any](x T[P]) { x.m(42) }`,
+		{`package r0; type T[P1 any] struct{}; func (_ T[P2]) m[Q any](Q) {}; func _[P3 any](x T[P3]) { x.m(42) }`,
-			`m`,
+			[]testInst{
-			[]string{`int`},
+				{`T`, []string{`P2`}, `struct{}`},
-			`func(int)`,
+				{`T`, []string{`P3`}, `struct{}`},
+				{`m`, []string{`int`}, `func(int)`},
+			},
 		},
 		// TODO(gri) record method type parameters in syntax.FuncType so we can check this
 		// {`package r1; type T interface{ m[P any](P) }; func _(x T) { x.m(4.2) }`,
@@ -474,97 +467,113 @@ func TestInstanceInfo(t *testing.T) {
 		// 	`func(float64)`,
 		// },
 
-		{`package s1; func f[T any, P interface{~*T}](x T) {}; func _(x string) { f(x) }`,
+		{`package s1; func f[T any, P interface{*T}](x T) {}; func _(x string) { f(x) }`,
-			`f`,
+			[]testInst{{`f`, []string{`string`, `*string`}, `func(x string)`}},
-			[]string{`string`, `*string`},
-			`func(x string)`,
 		},
-		{`package s2; func f[T any, P interface{~*T}](x []T) {}; func _(x []int) { f(x) }`,
+		{`package s2; func f[T any, P interface{*T}](x []T) {}; func _(x []int) { f(x) }`,
-			`f`,
+			[]testInst{{`f`, []string{`int`, `*int`}, `func(x []int)`}},
-			[]string{`int`, `*int`},
-			`func(x []int)`,
 		},
-		{`package s3; type C[T any] interface{~chan<- T}; func f[T any, P C[T]](x []T) {}; func _(x []int) { f(x) }`,
+		{`package s3; type C[T any] interface{chan<- T}; func f[T any, P C[T]](x []T) {}; func _(x []int) { f(x) }`,
-			`f`,
+			[]testInst{
-			[]string{`int`, `chan<- int`},
+				{`C`, []string{`T`}, `interface{chan<- T}`},
-			`func(x []int)`,
+				{`f`, []string{`int`, `chan<- int`}, `func(x []int)`},
+			},
 		},
-		{`package s4; type C[T any] interface{~chan<- T}; func f[T any, P C[T], Q C[[]*P]](x []T) {}; func _(x []int) { f(x) }`,
+		{`package s4; type C[T any] interface{chan<- T}; func f[T any, P C[T], Q C[[]*P]](x []T) {}; func _(x []int) { f(x) }`,
-			`f`,
+			[]testInst{
-			[]string{`int`, `chan<- int`, `chan<- []*chan<- int`},
+				{`C`, []string{`T`}, `interface{chan<- T}`},
-			`func(x []int)`,
+				{`C`, []string{`[]*P`}, `interface{chan<- []*P}`},
+				{`f`, []string{`int`, `chan<- int`, `chan<- []*chan<- int`}, `func(x []int)`},
+			},
 		},
 
-		{`package t1; func f[T any, P interface{~*T}]() T { panic(0) }; func _() { _ = f[string] }`,
+		{`package t1; func f[T any, P interface{*T}]() T { panic(0) }; func _() { _ = f[string] }`,
-			`f`,
+			[]testInst{{`f`, []string{`string`, `*string`}, `func() string`}},
-			[]string{`string`, `*string`},
-			`func() string`,
 		},
-		{`package t2; func f[T any, P interface{~*T}]() T { panic(0) }; func _() { _ = (f[string]) }`,
+		{`package t2; func f[T any, P interface{*T}]() T { panic(0) }; func _() { _ = (f[string]) }`,
-			`f`,
+			[]testInst{{`f`, []string{`string`, `*string`}, `func() string`}},
-			[]string{`string`, `*string`},
-			`func() string`,
 		},
-		{`package t3; type C[T any] interface{~chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T { return nil }; func _() { _ = f[int] }`,
+		{`package t3; type C[T any] interface{chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T { return nil }; func _() { _ = f[int] }`,
-			`f`,
+			[]testInst{
-			[]string{`int`, `chan<- int`, `chan<- []*chan<- int`},
+				{`C`, []string{`T`}, `interface{chan<- T}`},
-			`func() []int`,
+				{`C`, []string{`[]*P`}, `interface{chan<- []*P}`},
+				{`f`, []string{`int`, `chan<- int`, `chan<- []*chan<- int`}, `func() []int`},
+			},
 		},
-		{`package t4; type C[T any] interface{~chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T { return nil }; func _() { _ = f[int] }`,
+		{`package t4; type C[T any] interface{chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T { return nil }; func _() { _ = (f[int]) }`,
-			`f`,
+			[]testInst{
-			[]string{`int`, `chan<- int`, `chan<- []*chan<- int`},
+				{`C`, []string{`T`}, `interface{chan<- T}`},
-			`func() []int`,
+				{`C`, []string{`[]*P`}, `interface{chan<- []*P}`},
+				{`f`, []string{`int`, `chan<- int`, `chan<- []*chan<- int`}, `func() []int`},
+			},
 		},
-		{`package i0; import lib "generic_lib"; func _() { lib.F(42) }`,
+		{`package i0; import "lib"; func _() { lib.F(42) }`,
-			`F`,
+			[]testInst{{`F`, []string{`int`}, `func(int)`}},
-			[]string{`int`},
-			`func(int)`,
 		},
+
+		{`package duplfunc0; func f[T any](T) {}; func _() { f(42); f("foo"); f[int](3) }`,
+			[]testInst{
+				{`f`, []string{`int`}, `func(int)`},
+				{`f`, []string{`string`}, `func(string)`},
+				{`f`, []string{`int`}, `func(int)`},
+			},
+		},
+		{`package duplfunc1; import "lib"; func _() { lib.F(42); lib.F("foo"); lib.F(3) }`,
+			[]testInst{
+				{`F`, []string{`int`}, `func(int)`},
+				{`F`, []string{`string`}, `func(string)`},
+				{`F`, []string{`int`}, `func(int)`},
+			},
+		},
+
 		{`package type0; type T[P interface{~int}] struct{ x P }; var _ T[int]`,
-			`T`,
+			[]testInst{{`T`, []string{`int`}, `struct{x int}`}},
-			[]string{`int`},
-			`struct{x int}`,
 		},
 		{`package type1; type T[P interface{~int}] struct{ x P }; var _ (T[int])`,
-			`T`,
+			[]testInst{{`T`, []string{`int`}, `struct{x int}`}},
-			[]string{`int`},
-			`struct{x int}`,
 		},
 		{`package type2; type T[P interface{~int}] struct{ x P }; var _ T[(int)]`,
-			`T`,
+			[]testInst{{`T`, []string{`int`}, `struct{x int}`}},
-			[]string{`int`},
-			`struct{x int}`,
 		},
 		{`package type3; type T[P1 interface{~[]P2}, P2 any] struct{ x P1; y P2 }; var _ T[[]int, int]`,
-			`T`,
+			[]testInst{{`T`, []string{`[]int`, `int`}, `struct{x []int; y int}`}},
-			[]string{`[]int`, `int`},
-			`struct{x []int; y int}`,
 		},
-		{`package type4; import lib "generic_lib"; var _ lib.T[int]`,
+		{`package type4; import "lib"; var _ lib.T[int]`,
-			`T`,
+			[]testInst{{`T`, []string{`int`}, `[]int`}},
-			[]string{`int`},
+		},
-			`[]int`,
+
+		{`package dupltype0; type T[P interface{~int}] struct{ x P }; var x T[int]; var y T[int]`,
+			[]testInst{
+				{`T`, []string{`int`}, `struct{x int}`},
+				{`T`, []string{`int`}, `struct{x int}`},
+			},
+		},
+		{`package dupltype1; type T[P ~int] struct{ x P }; func (r *T[Q]) add(z T[Q]) { r.x += z.x }`,
+			[]testInst{
+				{`T`, []string{`Q`}, `struct{x Q}`},
+				{`T`, []string{`Q`}, `struct{x Q}`},
+			},
+		},
+		{`package dupltype1; import "lib"; var x lib.T[int]; var y lib.T[int]; var z lib.T[string]`,
+			[]testInst{
+				{`T`, []string{`int`}, `[]int`},
+				{`T`, []string{`int`}, `[]int`},
+				{`T`, []string{`string`}, `[]string`},
+			},
 		},
 	}
 
 	for _, test := range tests {
-		const lib = `package generic_lib
-
-func F[P any](P) {}
-
-type T[P any] []P
-`
-
 		imports := make(testImporter)
 		conf := Config{Importer: imports}
-		instances := make(map[*syntax.Name]Instance)
+		instMap := make(map[*syntax.Name]Instance)
-		uses := make(map[*syntax.Name]Object)
+		useMap := make(map[*syntax.Name]Object)
 		makePkg := func(src string) *Package {
 			f, err := parseSrc("p.go", src)
 			if err != nil {
 				t.Fatal(err)
 			}
-			pkg, err := conf.Check("", []*syntax.File{f}, &Info{Instances: instances, Uses: uses})
+			pkg, err := conf.Check("", []*syntax.File{f}, &Info{Instances: instMap, Uses: useMap})
 			if err != nil {
 				t.Fatal(err)
 			}
@@ -574,60 +583,72 @@ type T[P any] []P
 		makePkg(lib)
 		pkg := makePkg(test.src)
 
-		// look for instance information
+		t.Run(pkg.Name(), func(t *testing.T) {
-		var targs []Type
+			// Sort instances in source order for stability.
-		var typ Type
+			instances := sortedInstances(instMap)
-		for ident, inst := range instances {
+			if got, want := len(instances), len(test.instances); got != want {
-			if syntax.String(ident) == test.name {
+				t.Fatalf("got %d instances, want %d", got, want)
-				for i := 0; i < inst.TypeArgs.Len(); i++ {
+			}
-					targs = append(targs, inst.TypeArgs.At(i))
-				}
-				typ = inst.Type
 
-				// Check that we can find the corresponding parameterized type.
+			// Pairwise compare with the expected instances.
-				ptype := uses[ident].Type()
+			for ii, inst := range instances {
+				var targs []Type
+				for i := 0; i < inst.Inst.TypeArgs.Len(); i++ {
+					targs = append(targs, inst.Inst.TypeArgs.At(i))
+				}
+				typ := inst.Inst.Type
+
+				testInst := test.instances[ii]
+				if got := inst.Name.Value; got != testInst.name {
+					t.Fatalf("got name %s, want %s", got, testInst.name)
+				}
+
+				if len(targs) != len(testInst.targs) {
+					t.Fatalf("got %d type arguments; want %d", len(targs), len(testInst.targs))
+				}
+				for i, targ := range targs {
+					if got := targ.String(); got != testInst.targs[i] {
+						t.Errorf("type argument %d: got %s; want %s", i, got, testInst.targs[i])
+					}
+				}
+				if got := typ.Underlying().String(); got != testInst.typ {
+					t.Errorf("package %s: got %s; want %s", pkg.Name(), got, testInst.typ)
+				}
+
+				// Verify the invariant that re-instantiating the corresponding generic
+				// type with TypeArgs results in an identical instance.
+				ptype := useMap[inst.Name].Type()
 				lister, _ := ptype.(interface{ TypeParams() *TypeParamList })
 				if lister == nil || lister.TypeParams().Len() == 0 {
-					t.Errorf("package %s: info.Types[%v] = %v, want parameterized type", pkg.Name(), ident, ptype)
+					t.Fatalf("info.Types[%v] = %v, want parameterized type", inst.Name, ptype)
-					continue
 				}
-
-				// Verify the invariant that re-instantiating the generic type with
-				// TypeArgs results in an equivalent type.
 				inst2, err := Instantiate(nil, ptype, targs, true)
 				if err != nil {
 					t.Errorf("Instantiate(%v, %v) failed: %v", ptype, targs, err)
 				}
-				if !Identical(inst.Type, inst2) {
+				if !Identical(inst.Inst.Type, inst2) {
-					t.Errorf("%v and %v are not identical", inst.Type, inst2)
+					t.Errorf("%v and %v are not identical", inst.Inst.Type, inst2)
 				}
-				break
 			}
-		}
+		})
-		if targs == nil {
-			t.Errorf("package %s: no instance information found for %s", pkg.Name(), test.name)
-			continue
-		}
-
-		// check that type arguments are correct
-		if len(targs) != len(test.targs) {
-			t.Errorf("package %s: got %d type arguments; want %d", pkg.Name(), len(targs), len(test.targs))
-			continue
-		}
-		for i, targ := range targs {
-			if got := targ.String(); got != test.targs[i] {
-				t.Errorf("package %s, %d. type argument: got %s; want %s", pkg.Name(), i, got, test.targs[i])
-				continue
-			}
-		}
-
-		// check that the types match
-		if got := typ.Underlying().String(); got != test.typ {
-			t.Errorf("package %s: got %s; want %s", pkg.Name(), got, test.typ)
-		}
 	}
 }
 
+type recordedInstance struct {
+	Name *syntax.Name
+	Inst Instance
+}
+
+func sortedInstances(m map[*syntax.Name]Instance) (instances []recordedInstance) {
+	for id, inst := range m {
+		instances = append(instances, recordedInstance{id, inst})
+	}
+	sort.Slice(instances, func(i, j int) bool {
+		return instances[i].Name.Pos().Cmp(instances[j].Name.Pos()) < 0
+	})
+	return instances
+}
+
 func TestDefsInfo(t *testing.T) {
 	var tests = []struct {
 		src  string
@@ -1697,7 +1718,7 @@ func F(){
 	var F = /*F=func:12*/ F /*F=var:17*/ ; _ = F
 
 	var a []int
-	for i, x := range /*i=undef*/ /*x=var:16*/ a /*i=var:20*/ /*x=var:20*/ { _ = i; _ = x }
+	for i, x := range a /*i=undef*/ /*x=var:16*/ { _ = i; _ = x }
 
 	var i interface{}
 	switch y := i.(type) { /*y=undef*/
@@ -2313,27 +2334,27 @@ type Bad Bad // invalid type
 	conf := Config{Error: func(error) {}}
 	pkg, _ := conf.Check(f.PkgName.Value, []*syntax.File{f}, nil)
 
-	scope := pkg.Scope()
+	lookup := func(tname string) Type { return pkg.Scope().Lookup(tname).Type() }
 	var (
-		EmptyIface   = scope.Lookup("EmptyIface").Type().Underlying().(*Interface)
+		EmptyIface   = lookup("EmptyIface").Underlying().(*Interface)
-		I            = scope.Lookup("I").Type().(*Named)
+		I            = lookup("I").(*Named)
 		II           = I.Underlying().(*Interface)
-		C            = scope.Lookup("C").Type().(*Named)
+		C            = lookup("C").(*Named)
 		CI           = C.Underlying().(*Interface)
-		Integer      = scope.Lookup("Integer").Type().Underlying().(*Interface)
+		Integer      = lookup("Integer").Underlying().(*Interface)
-		EmptyTypeSet = scope.Lookup("EmptyTypeSet").Type().Underlying().(*Interface)
+		EmptyTypeSet = lookup("EmptyTypeSet").Underlying().(*Interface)
-		N1           = scope.Lookup("N1").Type()
+		N1           = lookup("N1")
 		N1p          = NewPointer(N1)
-		N2           = scope.Lookup("N2").Type()
+		N2           = lookup("N2")
 		N2p          = NewPointer(N2)
-		N3           = scope.Lookup("N3").Type()
+		N3           = lookup("N3")
-		N4           = scope.Lookup("N4").Type()
+		N4           = lookup("N4")
-		Bad          = scope.Lookup("Bad").Type()
+		Bad          = lookup("Bad")
 	)
 
 	tests := []struct {
-		t    Type
+		V    Type
-		i    *Interface
+		T    *Interface
 		want bool
 	}{
 		{I, II, true},
@@ -2364,8 +2385,20 @@ type Bad Bad // invalid type
 	}
 
 	for _, test := range tests {
-		if got := Implements(test.t, test.i); got != test.want {
+		if got := Implements(test.V, test.T); got != test.want {
-			t.Errorf("Implements(%s, %s) = %t, want %t", test.t, test.i, got, test.want)
+			t.Errorf("Implements(%s, %s) = %t, want %t", test.V, test.T, got, test.want)
+		}
+
+		// The type assertion x.(T) is valid if T is an interface or if T implements the type of x.
+		// The assertion is never valid if T is a bad type.
+		V := test.T
+		T := test.V
+		want := false
+		if _, ok := T.Underlying().(*Interface); (ok || Implements(T, V)) && T != Bad {
+			want = true
+		}
+		if got := AssertableTo(V, T); got != want {
+			t.Errorf("AssertableTo(%s, %s) = %t, want %t", V, T, got, want)
 		}
 	}
 }

src/cmd/compile/internal/types2/assignments.go

@@ -294,15 +294,14 @@ func (check *Checker) typesSummary(list []Type, variadic bool) string {
 	return "(" + strings.Join(res, ", ") + ")"
 }
 
-func (check *Checker) assignError(rhs []syntax.Expr, nvars, nvals int) {
+func measure(x int, unit string) string {
-	measure := func(x int, unit string) string {
+	if x != 1 {
-		s := fmt.Sprintf("%d %s", x, unit)
+		unit += "s"
-		if x != 1 {
-			s += "s"
-		}
-		return s
 	}
+	return fmt.Sprintf("%d %s", x, unit)
+}
 
+func (check *Checker) assignError(rhs []syntax.Expr, nvars, nvals int) {
 	vars := measure(nvars, "variable")
 	vals := measure(nvals, "value")
 	rhs0 := rhs[0]

src/cmd/compile/internal/types2/builtins.go

@@ -82,10 +82,24 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		// of S and the respective parameter passing rules apply."
 		S := x.typ
 		var T Type
-		if s, _ := structuralType(S).(*Slice); s != nil {
+		if s, _ := coreType(S).(*Slice); s != nil {
 			T = s.elem
 		} else {
-			check.errorf(x, invalidArg+"%s is not a slice", x)
+			var cause string
+			switch {
+			case x.isNil():
+				cause = "have untyped nil"
+			case isTypeParam(S):
+				if u := coreType(S); u != nil {
+					cause = check.sprintf("%s has core type %s", x, u)
+				} else {
+					cause = check.sprintf("%s has no core type", x)
+				}
+			default:
+				cause = check.sprintf("have %s", x)
+			}
+			// don't use invalidArg prefix here as it would repeat "argument" in the error message
+			check.errorf(x, "first argument to append must be a slice; %s", cause)
 			return
 		}
 
@@ -101,7 +115,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 				if x.mode == invalid {
 					return
 				}
-				if t := structuralString(x.typ); t != nil && isString(t) {
+				if t := coreString(x.typ); t != nil && isString(t) {
 					if check.Types != nil {
 						sig := makeSig(S, S, x.typ)
 						sig.variadic = true
@@ -331,14 +345,14 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 
 	case _Copy:
 		// copy(x, y []T) int
-		dst, _ := structuralType(x.typ).(*Slice)
+		dst, _ := coreType(x.typ).(*Slice)
 
 		var y operand
 		arg(&y, 1)
 		if y.mode == invalid {
 			return
 		}
-		src0 := structuralString(y.typ)
+		src0 := coreString(y.typ)
 		if src0 != nil && isString(src0) {
 			src0 = NewSlice(universeByte)
 		}
@@ -472,13 +486,13 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		}
 
 		var min int // minimum number of arguments
-		switch structuralType(T).(type) {
+		switch coreType(T).(type) {
 		case *Slice:
 			min = 2
 		case *Map, *Chan:
 			min = 1
 		case nil:
-			check.errorf(arg0, invalidArg+"cannot make %s: no structural type", arg0)
+			check.errorf(arg0, invalidArg+"cannot make %s: no core type", arg0)
 			return
 		default:
 			check.errorf(arg0, invalidArg+"cannot make %s; type must be slice, map, or channel", arg0)

src/cmd/compile/internal/types2/call.go

@@ -168,7 +168,7 @@ func (check *Checker) callExpr(x *operand, call *syntax.CallExpr) exprKind {
 	cgocall := x.mode == cgofunc
 
 	// a type parameter may be "called" if all types have the same signature
-	sig, _ := structuralType(x.typ).(*Signature)
+	sig, _ := coreType(x.typ).(*Signature)
 	if sig == nil {
 		check.errorf(x, invalidOp+"cannot call non-function %s", x)
 		x.mode = invalid
@@ -423,7 +423,7 @@ var cgoPrefixes = [...]string{
 	"_Cmacro_", // function to evaluate the expanded expression
 }
 
-func (check *Checker) selector(x *operand, e *syntax.SelectorExpr) {
+func (check *Checker) selector(x *operand, e *syntax.SelectorExpr, def *Named) {
 	// these must be declared before the "goto Error" statements
 	var (
 		obj      Object
@@ -525,7 +525,17 @@ func (check *Checker) selector(x *operand, e *syntax.SelectorExpr) {
 	}
 
 	check.exprOrType(x, e.X, false)
-	if x.mode == invalid {
+	switch x.mode {
+	case typexpr:
+		// don't crash for "type T T.x" (was issue #51509)
+		if def != nil && x.typ == def {
+			check.cycleError([]Object{def.obj})
+			goto Error
+		}
+	case builtin:
+		check.errorf(e.Pos(), "cannot select on %s", x)
+		goto Error
+	case invalid:
 		goto Error
 	}
 

src/cmd/compile/internal/types2/check.go

@@ -18,19 +18,6 @@ var nopos syntax.Pos
 // debugging/development support
 const debug = false // leave on during development
 
-// If forceStrict is set, the type-checker enforces additional
-// rules not specified by the Go 1 spec, but which will
-// catch guaranteed run-time errors if the respective
-// code is executed. In other words, programs passing in
-// strict mode are Go 1 compliant, but not all Go 1 programs
-// will pass in strict mode. The additional rules are:
-//
-// - A type assertion x.(T) where T is an interface type
-//   is invalid if any (statically known) method that exists
-//   for both x and T have different signatures.
-//
-const forceStrict = false
-
 // exprInfo stores information about an untyped expression.
 type exprInfo struct {
 	isLhs bool // expression is lhs operand of a shift with delayed type-check
@@ -139,7 +126,7 @@ type Checker struct {
 	untyped  map[syntax.Expr]exprInfo // map of expressions without final type
 	delayed  []action                 // stack of delayed action segments; segments are processed in FIFO order
 	objPath  []Object                 // path of object dependencies during type inference (for cycle reporting)
-	defTypes []*Named                 // defined types created during type checking, for final validation.
+	cleaners []cleaner                // list of types that may need a final cleanup at the end of type-checking
 
 	// environment within which the current object is type-checked (valid only
 	// for the duration of type-checking a specific object)
@@ -218,6 +205,16 @@ func (check *Checker) pop() Object {
 	return obj
 }
 
+type cleaner interface {
+	cleanup()
+}
+
+// needsCleanup records objects/types that implement the cleanup method
+// which will be called at the end of type-checking.
+func (check *Checker) needsCleanup(c cleaner) {
+	check.cleaners = append(check.cleaners, c)
+}
+
 // NewChecker returns a new Checker instance for a given package.
 // Package files may be added incrementally via checker.Files.
 func NewChecker(conf *Config, pkg *Package, info *Info) *Checker {
@@ -260,6 +257,8 @@ func (check *Checker) initFiles(files []*syntax.File) {
 	check.methods = nil
 	check.untyped = nil
 	check.delayed = nil
+	check.objPath = nil
+	check.cleaners = nil
 
 	// determine package name and collect valid files
 	pkg := check.pkg
@@ -328,8 +327,8 @@ func (check *Checker) checkFiles(files []*syntax.File) (err error) {
 	print("== processDelayed ==")
 	check.processDelayed(0) // incl. all functions
 
-	print("== expandDefTypes ==")
+	print("== cleanup ==")
-	check.expandDefTypes()
+	check.cleanup()
 
 	print("== initOrder ==")
 	check.initOrder()
@@ -357,7 +356,6 @@ func (check *Checker) checkFiles(files []*syntax.File) (err error) {
 	check.recvTParamMap = nil
 	check.brokenAliases = nil
 	check.unionTypeSets = nil
-	check.defTypes = nil
 	check.ctxt = nil
 
 	// TODO(gri) There's more memory we should release at this point.
@@ -385,27 +383,13 @@ func (check *Checker) processDelayed(top int) {
 	check.delayed = check.delayed[:top]
 }
 
-func (check *Checker) expandDefTypes() {
+// cleanup runs cleanup for all collected cleaners.
-	// Ensure that every defined type created in the course of type-checking has
+func (check *Checker) cleanup() {
-	// either non-*Named underlying, or is unresolved.
+	// Don't use a range clause since Named.cleanup may add more cleaners.
-	//
+	for i := 0; i < len(check.cleaners); i++ {
-	// This guarantees that we don't leak any types whose underlying is *Named,
+		check.cleaners[i].cleanup()
-	// because any unresolved instances will lazily compute their underlying by
-	// substituting in the underlying of their origin. The origin must have
-	// either been imported or type-checked and expanded here, and in either case
-	// its underlying will be fully expanded.
-	for i := 0; i < len(check.defTypes); i++ {
-		n := check.defTypes[i]
-		switch n.underlying.(type) {
-		case nil:
-			if n.resolver == nil {
-				panic("nil underlying")
-			}
-		case *Named:
-			n.under() // n.under may add entries to check.defTypes
-		}
-		n.check = nil
 	}
+	check.cleaners = nil
 }
 
 func (check *Checker) record(x *operand) {

src/cmd/compile/internal/types2/compilersupport.go

@@ -19,12 +19,12 @@ func AsSignature(t Type) *Signature {
 	return u
 }
 
-// If typ is a type parameter, structuralType returns the single underlying
+// If typ is a type parameter, CoreType returns the single underlying
 // type of all types in the corresponding type constraint if it exists, or
 // nil otherwise. If the type set contains only unrestricted and restricted
 // channel types (with identical element types), the single underlying type
 // is the restricted channel type if the restrictions are always the same.
-// If typ is not a type parameter, structuralType returns the underlying type.
+// If typ is not a type parameter, CoreType returns the underlying type.
-func StructuralType(t Type) Type {
+func CoreType(t Type) Type {
-	return structuralType(t)
+	return coreType(t)
 }

src/cmd/compile/internal/types2/conversions.go

@@ -49,11 +49,14 @@ func (check *Checker) conversion(x *operand, T Type) {
 		// have specific types, constant x cannot be
 		// converted.
 		ok = T.(*TypeParam).underIs(func(u Type) bool {
-			// t is nil if there are no specific type terms
+			// u is nil if there are no specific type terms
 			if u == nil {
 				cause = check.sprintf("%s does not contain specific types", T)
 				return false
 			}
+			if isString(x.typ) && isBytesOrRunes(u) {
+				return true
+			}
 			if !constConvertibleTo(u, nil) {
 				cause = check.sprintf("cannot convert %s to %s (in %s)", x, u, T)
 				return false

src/cmd/compile/internal/types2/decl.go

@@ -569,7 +569,6 @@ func (check *Checker) collectTypeParams(dst **TypeParamList, list []*syntax.Fiel
 
 	// Keep track of bounds for later validation.
 	var bound Type
-	var bounds []Type
 	for i, f := range list {
 		// Optimization: Re-use the previous type bound if it hasn't changed.
 		// This also preserves the grouped output of type parameter lists
@@ -584,7 +583,6 @@ func (check *Checker) collectTypeParams(dst **TypeParamList, list []*syntax.Fiel
 				check.error(f.Type, "cannot use a type parameter as constraint")
 				bound = Typ[Invalid]
 			}
-			bounds = append(bounds, bound)
 		}
 		tparams[i].bound = bound
 	}

src/cmd/compile/internal/types2/errors.go

@@ -124,6 +124,17 @@ func sprintf(qf Qualifier, debug bool, format string, args ...interface{}) strin
 			}
 			buf.WriteByte(']')
 			arg = buf.String()
+		case []*TypeParam:
+			var buf bytes.Buffer
+			buf.WriteByte('[')
+			for i, x := range a {
+				if i > 0 {
+					buf.WriteString(", ")
+				}
+				buf.WriteString(typeString(x, qf, debug)) // use typeString so we get subscripts when debugging
+			}
+			buf.WriteByte(']')
+			arg = buf.String()
 		}
 		args[i] = arg
 	}

src/cmd/compile/internal/types2/expr.go

@@ -182,9 +182,9 @@ func (check *Checker) unary(x *operand, e *syntax.Operation) {
 		return
 
 	case syntax.Recv:
-		u := structuralType(x.typ)
+		u := coreType(x.typ)
 		if u == nil {
-			check.errorf(x, invalidOp+"cannot receive from %s: no structural type", x)
+			check.errorf(x, invalidOp+"cannot receive from %s: no core type", x)
 			x.mode = invalid
 			return
 		}
@@ -899,7 +899,7 @@ func (check *Checker) incomparableCause(typ Type) string {
 	}
 	// see if we can extract a more specific error
 	var cause string
-	comparable(typ, nil, func(format string, args ...interface{}) {
+	comparable(typ, true, nil, func(format string, args ...interface{}) {
 		cause = check.sprintf(format, args...)
 	})
 	return cause
@@ -1359,7 +1359,11 @@ func (check *Checker) exprInternal(x *operand, e syntax.Expr, hint Type) exprKin
 		case hint != nil:
 			// no composite literal type present - use hint (element type of enclosing type)
 			typ = hint
-			base, _ = deref(structuralType(typ)) // *T implies &T{}
+			base, _ = deref(coreType(typ)) // *T implies &T{}
+			if base == nil {
+				check.errorf(e, "invalid composite literal element type %s: no core type", typ)
+				goto Error
+			}
 
 		default:
 			// TODO(gri) provide better error messages depending on context
@@ -1367,7 +1371,7 @@ func (check *Checker) exprInternal(x *operand, e syntax.Expr, hint Type) exprKin
 			goto Error
 		}
 
-		switch utyp := structuralType(base).(type) {
+		switch utyp := coreType(base).(type) {
 		case *Struct:
 			// Prevent crash if the struct referred to is not yet set up.
 			// See analogous comment for *Array.
@@ -1552,7 +1556,7 @@ func (check *Checker) exprInternal(x *operand, e syntax.Expr, hint Type) exprKin
 		return kind
 
 	case *syntax.SelectorExpr:
-		check.selector(x, e)
+		check.selector(x, e, nil)
 
 	case *syntax.IndexExpr:
 		if check.indexExpr(x, e) {
@@ -1638,6 +1642,7 @@ func (check *Checker) exprInternal(x *operand, e syntax.Expr, hint Type) exprKin
 				case invalid:
 					goto Error
 				case typexpr:
+					check.validVarType(e.X, x.typ)
 					x.typ = &Pointer{base: x.typ}
 				default:
 					var base Type

src/cmd/compile/internal/types2/index.go

@@ -182,7 +182,7 @@ func (check *Checker) indexExpr(x *operand, e *syntax.IndexExpr) (isFuncInst boo
 	}
 
 	if !valid {
-		check.errorf(x, invalidOp+"cannot index %s", x)
+		check.errorf(e.Pos(), invalidOp+"cannot index %s", x)
 		x.mode = invalid
 		return false
 	}
@@ -213,9 +213,9 @@ func (check *Checker) sliceExpr(x *operand, e *syntax.SliceExpr) {
 
 	valid := false
 	length := int64(-1) // valid if >= 0
-	switch u := structuralString(x.typ).(type) {
+	switch u := coreString(x.typ).(type) {
 	case nil:
-		check.errorf(x, invalidOp+"cannot slice %s: %s has no structural type", x, x.typ)
+		check.errorf(x, invalidOp+"cannot slice %s: %s has no core type", x, x.typ)
 		x.mode = invalid
 		return
 

src/cmd/compile/internal/types2/infer.go

@@ -41,6 +41,13 @@ func (check *Checker) infer(pos syntax.Pos, tparams []*TypeParam, targs []Type,
 		}()
 	}
 
+	if traceInference {
+		check.dump("-- inferA %s%s ➞ %s", tparams, params, targs)
+		defer func() {
+			check.dump("=> inferA %s ➞ %s", tparams, result)
+		}()
+	}
+
 	// There must be at least one type parameter, and no more type arguments than type parameters.
 	n := len(tparams)
 	assert(n > 0 && len(targs) <= n)
@@ -54,6 +61,64 @@ func (check *Checker) infer(pos syntax.Pos, tparams []*TypeParam, targs []Type,
 	}
 	// len(targs) < n
 
+	const enableTparamRenaming = true
+	if enableTparamRenaming {
+		// For the purpose of type inference we must differentiate type parameters
+		// occurring in explicit type or value function arguments from the type
+		// parameters we are solving for via unification, because they may be the
+		// same in self-recursive calls. For example:
+		//
+		//  func f[P *Q, Q any](p P, q Q) {
+		//    f(p)
+		//  }
+		//
+		// In this example, the fact that the P used in the instantation f[P] has
+		// the same pointer identity as the P we are trying to solve for via
+		// unification is coincidental: there is nothing special about recursive
+		// calls that should cause them to conflate the identity of type arguments
+		// with type parameters. To put it another way: any such self-recursive
+		// call is equivalent to a mutually recursive call, which does not run into
+		// any problems of type parameter identity. For example, the following code
+		// is equivalent to the code above.
+		//
+		//  func f[P interface{*Q}, Q any](p P, q Q) {
+		//    f2(p)
+		//  }
+		//
+		//  func f2[P interface{*Q}, Q any](p P, q Q) {
+		//    f(p)
+		//  }
+		//
+		// We can turn the first example into the second example by renaming type
+		// parameters in the original signature to give them a new identity. As an
+		// optimization, we do this only for self-recursive calls.
+
+		// We can detect if we are in a self-recursive call by comparing the
+		// identity of the first type parameter in the current function with the
+		// first type parameter in tparams. This works because type parameters are
+		// unique to their type parameter list.
+		selfRecursive := check.sig != nil && check.sig.tparams.Len() > 0 && tparams[0] == check.sig.tparams.At(0)
+
+		if selfRecursive {
+			// In self-recursive inference, rename the type parameters with new type
+			// parameters that are the same but for their pointer identity.
+			tparams2 := make([]*TypeParam, len(tparams))
+			for i, tparam := range tparams {
+				tname := NewTypeName(tparam.Obj().Pos(), tparam.Obj().Pkg(), tparam.Obj().Name(), nil)
+				tparams2[i] = NewTypeParam(tname, nil)
+				tparams2[i].index = tparam.index // == i
+			}
+
+			renameMap := makeRenameMap(tparams, tparams2)
+			for i, tparam := range tparams {
+				tparams2[i].bound = check.subst(pos, tparam.bound, renameMap, nil)
+			}
+
+			tparams = tparams2
+			params = check.subst(pos, params, renameMap, nil).(*Tuple)
+		}
+	}
+
 	// If we have more than 2 arguments, we may have arguments with named and unnamed types.
 	// If that is the case, permutate params and args such that the arguments with named
 	// types are first in the list. This doesn't affect type inference if all types are taken
@@ -403,6 +468,13 @@ func (w *tpWalker) isParameterizedTypeList(list []Type) bool {
 func (check *Checker) inferB(pos syntax.Pos, tparams []*TypeParam, targs []Type) (types []Type, index int) {
 	assert(len(tparams) >= len(targs) && len(targs) > 0)
 
+	if traceInference {
+		check.dump("-- inferB %s ➞ %s", tparams, targs)
+		defer func() {
+			check.dump("=> inferB %s ➞ %s", tparams, types)
+		}()
+	}
+
 	// Setup bidirectional unification between constraints
 	// and the corresponding type arguments (which may be nil!).
 	u := newUnifier(false)
@@ -416,27 +488,88 @@ func (check *Checker) inferB(pos syntax.Pos, tparams []*TypeParam, targs []Type)
 		}
 	}
 
-	// If a constraint has a structural type, unify the corresponding type parameter with it.
+	// Repeatedly apply constraint type inference as long as
-	for _, tpar := range tparams {
+	// there are still unknown type arguments and progress is
-		sbound := structuralType(tpar)
+	// being made.
-		if sbound != nil {
+	//
-			// If the structural type is the underlying type of a single
+	// This is an O(n^2) algorithm where n is the number of
-			// defined type in the constraint, use that defined type instead.
+	// type parameters: if there is progress (and iteration
-			if named, _ := tpar.singleType().(*Named); named != nil {
+	// continues), at least one type argument is inferred
-				sbound = named
+	// per iteration and we have a doubly nested loop.
-			}
+	// In practice this is not a problem because the number
-			if !u.unify(tpar, sbound) {
+	// of type parameters tends to be very small (< 5 or so).
-				// TODO(gri) improve error message by providing the type arguments
+	// (It should be possible for unification to efficiently
-				//           which we know already
+	// signal newly inferred type arguments; then the loops
-				check.errorf(pos, "%s does not match %s", tpar, sbound)
+	// here could handle the respective type parameters only,
-				return nil, 0
+	// but that will come at a cost of extra complexity which
+	// may not be worth it.)
+	for n := u.x.unknowns(); n > 0; {
+		nn := n
+
+		for i, tpar := range tparams {
+			// If there is a core term (i.e., a core type with tilde information)
+			// unify the type parameter with the core type.
+			if core, single := coreTerm(tpar); core != nil {
+				// A type parameter can be unified with its core type in two cases.
+				tx := u.x.at(i)
+				switch {
+				case tx != nil:
+					// The corresponding type argument tx is known.
+					// In this case, if the core type has a tilde, the type argument's underlying
+					// type must match the core type, otherwise the type argument and the core type
+					// must match.
+					// If tx is an external type parameter, don't consider its underlying type
+					// (which is an interface). Core type unification will attempt to unify against
+					// core.typ.
+					// Note also that even with inexact unification we cannot leave away the under
+					// call here because it's possible that both tx and core.typ are named types,
+					// with under(tx) being a (named) basic type matching core.typ. Such cases do
+					// not match with inexact unification.
+					if core.tilde && !isTypeParam(tx) {
+						tx = under(tx)
+					}
+					if !u.unify(tx, core.typ) {
+						// TODO(gri) improve error message by providing the type arguments
+						//           which we know already
+						// Don't use term.String() as it always qualifies types, even if they
+						// are in the current package.
+						tilde := ""
+						if core.tilde {
+							tilde = "~"
+						}
+						check.errorf(pos, "%s does not match %s%s", tpar, tilde, core.typ)
+						return nil, 0
+					}
+
+				case single && !core.tilde:
+					// The corresponding type argument tx is unknown and there's a single
+					// specific type and no tilde.
+					// In this case the type argument must be that single type; set it.
+					u.x.set(i, core.typ)
+
+				default:
+					// Unification is not possible and no progress was made.
+					continue
+				}
+
+				// The number of known type arguments may have changed.
+				nn = u.x.unknowns()
+				if nn == 0 {
+					break // all type arguments are known
+				}
 			}
 		}
+
+		assert(nn <= n)
+		if nn == n {
+			break // no progress
+		}
+		n = nn
 	}
 
 	// u.x.types() now contains the incoming type arguments plus any additional type
-	// arguments which were inferred from structural types. The newly inferred non-
+	// arguments which were inferred from core terms. The newly inferred non-nil
-	// nil entries may still contain references to other type parameters.
+	// entries may still contain references to other type parameters.
 	// For instance, for [A any, B interface{ []C }, C interface{ *A }], if A == int
 	// was given, unification produced the type list [int, []C, *A]. We eliminate the
 	// remaining type parameters by substituting the type parameters in this type list
@@ -504,8 +637,8 @@ func (check *Checker) inferB(pos syntax.Pos, tparams []*TypeParam, targs []Type)
 	}
 
 	// Once nothing changes anymore, we may still have type parameters left;
-	// e.g., a structural constraint *P may match a type parameter Q but we
+	// e.g., a constraint with core type *P may match a type parameter Q but
-	// don't have any type arguments to fill in for *P or Q (issue #45548).
+	// we don't have any type arguments to fill in for *P or Q (issue #45548).
 	// Don't let such inferences escape, instead nil them out.
 	for i, typ := range types {
 		if typ != nil && isParameterized(tparams, typ) {
@@ -525,6 +658,42 @@ func (check *Checker) inferB(pos syntax.Pos, tparams []*TypeParam, targs []Type)
 	return
 }
 
+// If the type parameter has a single specific type S, coreTerm returns (S, true).
+// Otherwise, if tpar has a core type T, it returns a term corresponding to that
+// core type and false. In that case, if any term of tpar has a tilde, the core
+// term has a tilde. In all other cases coreTerm returns (nil, false).
+func coreTerm(tpar *TypeParam) (*term, bool) {
+	n := 0
+	var single *term // valid if n == 1
+	var tilde bool
+	tpar.is(func(t *term) bool {
+		if t == nil {
+			assert(n == 0)
+			return false // no terms
+		}
+		n++
+		single = t
+		if t.tilde {
+			tilde = true
+		}
+		return true
+	})
+	if n == 1 {
+		if debug {
+			assert(debug && under(single.typ) == coreType(tpar))
+		}
+		return single, true
+	}
+	if typ := coreType(tpar); typ != nil {
+		// A core type is always an underlying type.
+		// If any term of tpar has a tilde, we don't
+		// have a precise core type and we must return
+		// a tilde as well.
+		return &term{tilde, typ}, false
+	}
+	return nil, false
+}
+
 type cycleFinder struct {
 	tparams []*TypeParam
 	types   []Type
@@ -570,8 +739,6 @@ func (w *cycleFinder) typ(typ Type) {
 	//      in signatures where they are handled explicitly.
 
 	case *Signature:
-		// There are no "method types" so we should never see a recv.
-		assert(t.recv == nil)
 		if t.params != nil {
 			w.varList(t.params.vars)
 		}

src/cmd/compile/internal/types2/instantiate.go

@@ -15,10 +15,10 @@ import (
 
 // Instantiate instantiates the type orig with the given type arguments targs.
 // orig must be a *Named or a *Signature type. If there is no error, the
-// resulting Type is a new, instantiated (not parameterized) type of the same
+// resulting Type is an instantiated type of the same kind (either a *Named or
-// kind (either a *Named or a *Signature). Methods attached to a *Named type
+// a *Signature). Methods attached to a *Named type are also instantiated, and
-// are also instantiated, and associated with a new *Func that has the same
+// associated with a new *Func that has the same position as the original
-// position as the original method, but nil function scope.
+// method, but nil function scope.
 //
 // If ctxt is non-nil, it may be used to de-duplicate the instance against
 // previous instances with the same identity. As a special case, generic
@@ -204,7 +204,7 @@ func (check *Checker) implements(V, T Type) error {
 	// If T is comparable, V must be comparable.
 	// Remember as a pending error and report only if we don't have a more specific error.
 	var pending error
-	if Ti.IsComparable() && ((Vi != nil && !Vi.IsComparable()) || (Vi == nil && !Comparable(V))) {
+	if Ti.IsComparable() && !comparable(V, false, nil, nil) {
 		pending = errorf("%s does not implement comparable", V)
 	}
 

src/cmd/compile/internal/types2/interface.go

@@ -37,7 +37,7 @@ func NewInterfaceType(methods []*Func, embeddeds []Type) *Interface {
 	}
 
 	// set method receivers if necessary
-	typ := new(Interface)
+	typ := (*Checker)(nil).newInterface()
 	for _, m := range methods {
 		if sig := m.typ.(*Signature); sig.recv == nil {
 			sig.recv = NewVar(m.pos, m.pkg, "", typ)
@@ -54,6 +54,15 @@ func NewInterfaceType(methods []*Func, embeddeds []Type) *Interface {
 	return typ
 }
 
+// check may be nil
+func (check *Checker) newInterface() *Interface {
+	typ := &Interface{check: check}
+	if check != nil {
+		check.needsCleanup(typ)
+	}
+	return typ
+}
+
 // MarkImplicit marks the interface t as implicit, meaning this interface
 // corresponds to a constraint literal such as ~T or A|B without explicit
 // interface embedding. MarkImplicit should be called before any concurrent use
@@ -100,6 +109,11 @@ func (t *Interface) String() string   { return TypeString(t, nil) }
 // ----------------------------------------------------------------------------
 // Implementation
 
+func (t *Interface) cleanup() {
+	t.check = nil
+	t.embedPos = nil
+}
+
 func (check *Checker) interfaceType(ityp *Interface, iface *syntax.InterfaceType, def *Named) {
 	addEmbedded := func(pos syntax.Pos, typ Type) {
 		ityp.embeddeds = append(ityp.embeddeds, typ)
@@ -162,16 +176,10 @@ func (check *Checker) interfaceType(ityp *Interface, iface *syntax.InterfaceType
 	// (don't sort embeddeds: they must correspond to *embedPos entries)
 	sortMethods(ityp.methods)
 
-	// Compute type set with a non-nil *Checker as soon as possible
+	// Compute type set as soon as possible to report any errors.
-	// to report any errors. Subsequent uses of type sets will use
+	// Subsequent uses of type sets will use this computed type
-	// this computed type set and won't need to pass in a *Checker.
+	// set and won't need to pass in a *Checker.
-	//
-	// Pin the checker to the interface type in the interim, in case the type set
-	// must be used before delayed funcs are processed (see issue #48234).
-	// TODO(rfindley): clean up use of *Checker with computeInterfaceTypeSet
-	ityp.check = check
 	check.later(func() {
 		computeInterfaceTypeSet(check, iface.Pos(), ityp)
-		ityp.check = nil
 	}).describef(iface, "compute type set for %s", ityp)
 }

src/cmd/compile/internal/types2/lookup.go

@@ -66,12 +66,13 @@ func LookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
 
 	obj, index, indirect = lookupFieldOrMethod(T, addressable, pkg, name, false)
 
-	// If we didn't find anything and if we have a type parameter with a structural constraint,
+	// If we didn't find anything and if we have a type parameter with a core type,
-	// see if there is a matching field (but not a method, those need to be declared explicitly
+	// see if there is a matching field (but not a method, those need to be declared
-	// in the constraint). If the structural constraint is a named pointer type (see above), we
+	// explicitly in the constraint). If the constraint is a named pointer type (see
-	// are ok here because only fields are accepted as results.
+	// above), we are ok here because only fields are accepted as results.
-	if obj == nil && isTypeParam(T) {
+	const enableTParamFieldLookup = false // see issue #51576
-		if t := structuralType(T); t != nil {
+	if enableTParamFieldLookup && obj == nil && isTypeParam(T) {
+		if t := coreType(T); t != nil {
 			obj, index, indirect = lookupFieldOrMethod(t, addressable, pkg, name, false)
 			if _, ok := obj.(*Var); !ok {
 				obj, index, indirect = nil, nil, false // accept fields (variables) only
@@ -425,18 +426,31 @@ func (check *Checker) funcString(f *Func) string {
 // method required by V and whether it is missing or just has the wrong type.
 // The receiver may be nil if assertableTo is invoked through an exported API call
 // (such as AssertableTo), i.e., when all methods have been type-checked.
-// If the global constant forceStrict is set, assertions that are known to fail
+// TODO(gri) replace calls to this function with calls to newAssertableTo.
-// are not permitted.
 func (check *Checker) assertableTo(V *Interface, T Type) (method, wrongType *Func) {
 	// no static check is required if T is an interface
 	// spec: "If T is an interface type, x.(T) asserts that the
 	//        dynamic type of x implements the interface T."
-	if IsInterface(T) && !forceStrict {
+	if IsInterface(T) {
 		return
 	}
+	// TODO(gri) fix this for generalized interfaces
 	return check.missingMethod(T, V, false)
 }
 
+// newAssertableTo reports whether a value of type V can be asserted to have type T.
+// It also implements behavior for interfaces that currently are only permitted
+// in constraint position (we have not yet defined that behavior in the spec).
+func (check *Checker) newAssertableTo(V *Interface, T Type) error {
+	// no static check is required if T is an interface
+	// spec: "If T is an interface type, x.(T) asserts that the
+	//        dynamic type of x implements the interface T."
+	if IsInterface(T) {
+		return nil
+	}
+	return check.implements(T, V)
+}
+
 // deref dereferences typ if it is a *Pointer and returns its base and true.
 // Otherwise it returns (typ, false).
 func deref(typ Type) (Type, bool) {

src/cmd/compile/internal/types2/named.go

@@ -72,16 +72,36 @@ func (check *Checker) newNamed(obj *TypeName, orig *Named, underlying Type, tpar
 	}
 	// Ensure that typ is always expanded and sanity-checked.
 	if check != nil {
-		check.defTypes = append(check.defTypes, typ)
+		check.needsCleanup(typ)
 	}
 	return typ
 }
 
+func (t *Named) cleanup() {
+	// Ensure that every defined type created in the course of type-checking has
+	// either non-*Named underlying, or is unresolved.
+	//
+	// This guarantees that we don't leak any types whose underlying is *Named,
+	// because any unresolved instances will lazily compute their underlying by
+	// substituting in the underlying of their origin. The origin must have
+	// either been imported or type-checked and expanded here, and in either case
+	// its underlying will be fully expanded.
+	switch t.underlying.(type) {
+	case nil:
+		if t.resolver == nil {
+			panic("nil underlying")
+		}
+	case *Named:
+		t.under() // t.under may add entries to check.cleaners
+	}
+	t.check = nil
+}
+
 // Obj returns the type name for the declaration defining the named type t. For
-// instantiated types, this is the type name of the base type.
+// instantiated types, this is same as the type name of the origin type.
 func (t *Named) Obj() *TypeName { return t.orig.obj } // for non-instances this is the same as t.obj
 
-// Origin returns the parameterized type from which the named type t is
+// Origin returns the generic type from which the named type t is
 // instantiated. If t is not an instantiated type, the result is t.
 func (t *Named) Origin() *Named { return t.orig }
 
@@ -89,7 +109,7 @@ func (t *Named) Origin() *Named { return t.orig }
 //           between parameterized instantiated and non-instantiated types.
 
 // TypeParams returns the type parameters of the named type t, or nil.
-// The result is non-nil for an (originally) parameterized type even if it is instantiated.
+// The result is non-nil for an (originally) generic type even if it is instantiated.
 func (t *Named) TypeParams() *TypeParamList { return t.resolve(nil).tparams }
 
 // SetTypeParams sets the type parameters of the named type t.
@@ -102,7 +122,11 @@ func (t *Named) SetTypeParams(tparams []*TypeParam) {
 // TypeArgs returns the type arguments used to instantiate the named type t.
 func (t *Named) TypeArgs() *TypeList { return t.targs }
 
-// NumMethods returns the number of explicit methods whose receiver is named type t.
+// NumMethods returns the number of explicit methods defined for t.
+//
+// For an ordinary or instantiated type t, the receiver base type of these
+// methods will be the named type t. For an uninstantiated generic type t, each
+// method receiver will be instantiated with its receiver type parameters.
 func (t *Named) NumMethods() int { return t.resolve(nil).methods.Len() }
 
 // Method returns the i'th method of named type t for 0 <= i < t.NumMethods().
@@ -360,11 +384,11 @@ func expandNamed(ctxt *Context, n *Named, instPos syntax.Pos) (tparams *TypePara
 				// that it wasn't substituted. In this case we need to create a new
 				// *Interface before modifying receivers.
 				if iface == n.orig.underlying {
-					iface = &Interface{
+					old := iface
-						embeddeds: iface.embeddeds,
+					iface = check.newInterface()
-						complete:  iface.complete,
+					iface.embeddeds = old.embeddeds
-						implicit:  iface.implicit, // should be false but be conservative
+					iface.complete = old.complete
-					}
+					iface.implicit = old.implicit // should be false but be conservative
 					underlying = iface
 				}
 				iface.methods = methods

src/cmd/compile/internal/types2/predicates.go

@@ -31,7 +31,7 @@ func isBasic(t Type, info BasicInfo) bool {
 // The allX predicates below report whether t is an X.
 // If t is a type parameter the result is true if isX is true
 // for all specified types of the type parameter's type set.
-// allX is an optimized version of isX(structuralType(t)) (which
+// allX is an optimized version of isX(coreType(t)) (which
 // is the same as underIs(t, isX)).
 
 func allBoolean(t Type) bool         { return allBasic(t, IsBoolean) }
@@ -45,7 +45,7 @@ func allNumericOrString(t Type) bool { return allBasic(t, IsNumeric|IsString) }
 // allBasic reports whether under(t) is a basic type with the specified info.
 // If t is a type parameter, the result is true if isBasic(t, info) is true
 // for all specific types of the type parameter's type set.
-// allBasic(t, info) is an optimized version of isBasic(structuralType(t), info).
+// allBasic(t, info) is an optimized version of isBasic(coreType(t), info).
 func allBasic(t Type, info BasicInfo) bool {
 	if tpar, _ := t.(*TypeParam); tpar != nil {
 		return tpar.is(func(t *term) bool { return t != nil && isBasic(t.typ, info) })
@@ -102,11 +102,12 @@ func isGeneric(t Type) bool {
 
 // Comparable reports whether values of type T are comparable.
 func Comparable(T Type) bool {
-	return comparable(T, nil, nil)
+	return comparable(T, true, nil, nil)
 }
 
+// If dynamic is set, non-type parameter interfaces are always comparable.
 // If reportf != nil, it may be used to report why T is not comparable.
-func comparable(T Type, seen map[Type]bool, reportf func(string, ...interface{})) bool {
+func comparable(T Type, dynamic bool, seen map[Type]bool, reportf func(string, ...interface{})) bool {
 	if seen[T] {
 		return true
 	}
@@ -124,7 +125,7 @@ func comparable(T Type, seen map[Type]bool, reportf func(string, ...interface{})
 		return true
 	case *Struct:
 		for _, f := range t.fields {
-			if !comparable(f.typ, seen, nil) {
+			if !comparable(f.typ, dynamic, seen, nil) {
 				if reportf != nil {
 					reportf("struct containing %s cannot be compared", f.typ)
 				}
@@ -133,7 +134,7 @@ func comparable(T Type, seen map[Type]bool, reportf func(string, ...interface{})
 		}
 		return true
 	case *Array:
-		if !comparable(t.elem, seen, nil) {
+		if !comparable(t.elem, dynamic, seen, nil) {
 			if reportf != nil {
 				reportf("%s cannot be compared", t)
 			}
@@ -141,7 +142,7 @@ func comparable(T Type, seen map[Type]bool, reportf func(string, ...interface{})
 		}
 		return true
 	case *Interface:
-		return !isTypeParam(T) || t.typeSet().IsComparable(seen)
+		return dynamic && !isTypeParam(T) || t.typeSet().IsComparable(seen)
 	}
 	return false
 }

src/cmd/compile/internal/types2/resolver.go

@@ -413,7 +413,7 @@ func (check *Checker) collectObjects() {
 
 			case *syntax.TypeDecl:
 				if len(s.TParamList) != 0 && !check.allowVersion(pkg, 1, 18) {
-					check.softErrorf(s.TParamList[0], "type parameters require go1.18 or later")
+					check.versionErrorf(s.TParamList[0], "go1.18", "type parameter")
 				}
 				obj := NewTypeName(s.Name.Pos(), pkg, s.Name.Value, nil)
 				check.declarePkgObj(s.Name, obj, &declInfo{file: fileScope, tdecl: s})
@@ -458,7 +458,7 @@ func (check *Checker) collectObjects() {
 					check.recordDef(s.Name, obj)
 				}
 				if len(s.TParamList) != 0 && !check.allowVersion(pkg, 1, 18) && !hasTParamError {
-					check.softErrorf(s.TParamList[0], "type parameters require go1.18 or later")
+					check.versionErrorf(s.TParamList[0], "go1.18", "type parameter")
 				}
 				info := &declInfo{file: fileScope, fdecl: s}
 				// Methods are not package-level objects but we still track them in the

src/cmd/compile/internal/types2/signature.go

@@ -116,11 +116,10 @@ func (check *Checker) funcType(sig *Signature, recvPar *syntax.Field, tparams []
 			// lookup in the scope.
 			for i, p := range rparams {
 				if p.Value == "_" {
-					tpar := sig.rparams.At(i)
 					if check.recvTParamMap == nil {
 						check.recvTParamMap = make(map[*syntax.Name]*TypeParam)
 					}
-					check.recvTParamMap[p] = tpar
+					check.recvTParamMap[p] = tparams[i]
 				}
 			}
 			// determine receiver type to get its type parameters
@@ -136,22 +135,23 @@ func (check *Checker) funcType(sig *Signature, recvPar *syntax.Field, tparams []
 				}
 			}
 			// provide type parameter bounds
-			// - only do this if we have the right number (otherwise an error is reported elsewhere)
+			if len(tparams) == len(recvTParams) {
-			if sig.RecvTypeParams().Len() == len(recvTParams) {
+				smap := makeRenameMap(recvTParams, tparams)
-				// We have a list of *TypeNames but we need a list of Types.
+				for i, tpar := range tparams {
-				list := make([]Type, sig.RecvTypeParams().Len())
+					recvTPar := recvTParams[i]
-				for i, t := range sig.RecvTypeParams().list() {
+					check.mono.recordCanon(tpar, recvTPar)
-					list[i] = t
+					// recvTPar.bound is (possibly) parameterized in the context of the
-					check.mono.recordCanon(t, recvTParams[i])
+					// receiver type declaration. Substitute parameters for the current
-				}
+					// context.
-				smap := makeSubstMap(recvTParams, list)
+					tpar.bound = check.subst(tpar.obj.pos, recvTPar.bound, smap, nil)
-				for i, tpar := range sig.RecvTypeParams().list() {
-					bound := recvTParams[i].bound
-					// bound is (possibly) parameterized in the context of the
-					// receiver type declaration. Substitute parameters for the
-					// current context.
-					tpar.bound = check.subst(tpar.obj.pos, bound, smap, nil)
 				}
+			} else if len(tparams) < len(recvTParams) {
+				// Reporting an error here is a stop-gap measure to avoid crashes in the
+				// compiler when a type parameter/argument cannot be inferred later. It
+				// may lead to follow-on errors (see issues #51339, #51343).
+				// TODO(gri) find a better solution
+				got := measure(len(tparams), "type parameter")
+				check.errorf(recvPar, "got %s, but receiver base type declares %d", got, len(recvTParams))
 			}
 		}
 	}
@@ -194,66 +194,69 @@ func (check *Checker) funcType(sig *Signature, recvPar *syntax.Field, tparams []
 		case 1:
 			recv = recvList[0]
 		}
+		sig.recv = recv
 
-		// TODO(gri) We should delay rtyp expansion to when we actually need the
+		// Delay validation of receiver type as it may cause premature expansion
-		//           receiver; thus all checks here should be delayed to later.
+		// of types the receiver type is dependent on (see issues #51232, #51233).
-		rtyp, _ := deref(recv.typ)
+		check.later(func() {
+			rtyp, _ := deref(recv.typ)
 
-		// spec: "The receiver type must be of the form T or *T where T is a type name."
+			// spec: "The receiver type must be of the form T or *T where T is a type name."
-		// (ignore invalid types - error was reported before)
+			// (ignore invalid types - error was reported before)
-		if rtyp != Typ[Invalid] {
+			if rtyp != Typ[Invalid] {
-			var err string
+				var err string
-			switch T := rtyp.(type) {
+				switch T := rtyp.(type) {
-			case *Named:
+				case *Named:
-				T.resolve(check.bestContext(nil))
+					T.resolve(check.bestContext(nil))
-				// The receiver type may be an instantiated type referred to
+					// The receiver type may be an instantiated type referred to
-				// by an alias (which cannot have receiver parameters for now).
+					// by an alias (which cannot have receiver parameters for now).
-				if T.TypeArgs() != nil && sig.RecvTypeParams() == nil {
+					if T.TypeArgs() != nil && sig.RecvTypeParams() == nil {
-					check.errorf(recv.pos, "cannot define methods on instantiated type %s", recv.typ)
+						check.errorf(recv.pos, "cannot define methods on instantiated type %s", recv.typ)
-					break
+						break
-				}
+					}
-				// spec: "The type denoted by T is called the receiver base type; it must not
+					// spec: "The type denoted by T is called the receiver base type; it must not
-				// be a pointer or interface type and it must be declared in the same package
+					// be a pointer or interface type and it must be declared in the same package
-				// as the method."
+					// as the method."
-				if T.obj.pkg != check.pkg {
+					if T.obj.pkg != check.pkg {
-					err = "type not defined in this package"
+						err = "type not defined in this package"
+						if check.conf.CompilerErrorMessages {
+							check.errorf(recv.pos, "cannot define new methods on non-local type %s", recv.typ)
+							err = ""
+						}
+					} else {
+						// The underlying type of a receiver base type can be a type parameter;
+						// e.g. for methods with a generic receiver T[P] with type T[P any] P.
+						// TODO(gri) Such declarations are currently disallowed.
+						//           Revisit the need for underIs.
+						underIs(T, func(u Type) bool {
+							switch u := u.(type) {
+							case *Basic:
+								// unsafe.Pointer is treated like a regular pointer
+								if u.kind == UnsafePointer {
+									err = "unsafe.Pointer"
+									return false
+								}
+							case *Pointer, *Interface:
+								err = "pointer or interface type"
+								return false
+							}
+							return true
+						})
+					}
+				case *Basic:
+					err = "basic or unnamed type"
 					if check.conf.CompilerErrorMessages {
 						check.errorf(recv.pos, "cannot define new methods on non-local type %s", recv.typ)
 						err = ""
 					}
-				} else {
+				default:
-					// The underlying type of a receiver base type can be a type parameter;
+					check.errorf(recv.pos, "invalid receiver type %s", recv.typ)
-					// e.g. for methods with a generic receiver T[P] with type T[P any] P.
-					underIs(T, func(u Type) bool {
-						switch u := u.(type) {
-						case *Basic:
-							// unsafe.Pointer is treated like a regular pointer
-							if u.kind == UnsafePointer {
-								err = "unsafe.Pointer"
-								return false
-							}
-						case *Pointer, *Interface:
-							err = "pointer or interface type"
-							return false
-						}
-						return true
-					})
 				}
-			case *Basic:
+				if err != "" {
-				err = "basic or unnamed type"
+					check.errorf(recv.pos, "invalid receiver type %s (%s)", recv.typ, err)
-				if check.conf.CompilerErrorMessages {
-					check.errorf(recv.pos, "cannot define new methods on non-local type %s", recv.typ)
-					err = ""
 				}
-			default:
-				check.errorf(recv.pos, "invalid receiver type %s", recv.typ)
 			}
-			if err != "" {
+		}).describef(recv, "validate receiver %s", recv)
-				check.errorf(recv.pos, "invalid receiver type %s (%s)", recv.typ, err)
-				// ok to continue
-			}
-		}
-		sig.recv = recv
 	}
 
 	sig.params = NewTuple(params...)

src/cmd/compile/internal/types2/stmt.go

@@ -409,9 +409,9 @@ func (check *Checker) stmt(ctxt stmtContext, s syntax.Stmt) {
 		if ch.mode == invalid || val.mode == invalid {
 			return
 		}
-		u := structuralType(ch.typ)
+		u := coreType(ch.typ)
 		if u == nil {
-			check.errorf(s, invalidOp+"cannot send to %s: no structural type", &ch)
+			check.errorf(s, invalidOp+"cannot send to %s: no core type", &ch)
 			return
 		}
 		uch, _ := u.(*Chan)
@@ -626,14 +626,15 @@ func (check *Checker) stmt(ctxt stmtContext, s syntax.Stmt) {
 
 	case *syntax.ForStmt:
 		inner |= breakOk | continueOk
-		check.openScope(s, "for")
-		defer check.closeScope()
 
 		if rclause, _ := s.Init.(*syntax.RangeClause); rclause != nil {
 			check.rangeStmt(inner, s, rclause)
 			break
 		}
 
+		check.openScope(s, "for")
+		defer check.closeScope()
+
 		check.simpleStmt(s.Init)
 		if s.Cond != nil {
 			var x operand
@@ -809,8 +810,6 @@ func (check *Checker) typeSwitchStmt(inner stmtContext, s *syntax.SwitchStmt, gu
 }
 
 func (check *Checker) rangeStmt(inner stmtContext, s *syntax.ForStmt, rclause *syntax.RangeClause) {
-	// scope already opened
-
 	// determine lhs, if any
 	sKey := rclause.Lhs // possibly nil
 	var sValue, sExtra syntax.Expr
@@ -835,9 +834,9 @@ func (check *Checker) rangeStmt(inner stmtContext, s *syntax.ForStmt, rclause *s
 	// determine key/value types
 	var key, val Type
 	if x.mode != invalid {
-		// Ranging over a type parameter is permitted if it has a structural type.
+		// Ranging over a type parameter is permitted if it has a core type.
 		var cause string
-		u := structuralType(x.typ)
+		u := coreType(x.typ)
 		if t, _ := u.(*Chan); t != nil {
 			if sValue != nil {
 				check.softErrorf(sValue, "range over %s permits only one iteration variable", &x)
@@ -852,7 +851,7 @@ func (check *Checker) rangeStmt(inner stmtContext, s *syntax.ForStmt, rclause *s
 				// ok to continue
 			}
 			if u == nil {
-				cause = check.sprintf("%s has no structural type", x.typ)
+				cause = check.sprintf("%s has no core type", x.typ)
 			}
 		}
 		key, val = rangeKeyVal(u)
@@ -866,6 +865,11 @@ func (check *Checker) rangeStmt(inner stmtContext, s *syntax.ForStmt, rclause *s
 		}
 	}
 
+	// Open the for-statement block scope now, after the range clause.
+	// Iteration variables declared with := need to go in this scope (was issue #51437).
+	check.openScope(s, "range")
+	defer check.closeScope()
+
 	// check assignment to/declaration of iteration variables
 	// (irregular assignment, cannot easily map to existing assignment checks)
 
@@ -874,9 +878,7 @@ func (check *Checker) rangeStmt(inner stmtContext, s *syntax.ForStmt, rclause *s
 	rhs := [2]Type{key, val} // key, val may be nil
 
 	if rclause.Def {
-		// short variable declaration; variable scope starts after the range clause
+		// short variable declaration
-		// (the for loop opens a new scope, so variables on the lhs never redeclare
-		// previously declared variables)
 		var vars []*Var
 		for i, lhs := range lhs {
 			if lhs == nil {
@@ -913,12 +915,8 @@ func (check *Checker) rangeStmt(inner stmtContext, s *syntax.ForStmt, rclause *s
 
 		// declare variables
 		if len(vars) > 0 {
-			scopePos := syntax.EndPos(rclause.X) // TODO(gri) should this just be s.Body.Pos (spec clarification)?
+			scopePos := s.Body.Pos()
 			for _, obj := range vars {
-				// spec: "The scope of a constant or variable identifier declared inside
-				// a function begins at the end of the ConstSpec or VarSpec (ShortVarDecl
-				// for short variable declarations) and ends at the end of the innermost
-				// containing block."
 				check.declare(check.scope, nil /* recordDef already called */, obj, scopePos)
 			}
 		} else {

src/cmd/compile/internal/types2/subst.go

@@ -21,6 +21,17 @@ func makeSubstMap(tpars []*TypeParam, targs []Type) substMap {
 	return proj
 }
 
+// makeRenameMap is like makeSubstMap, but creates a map used to rename type
+// parameters in from with the type parameters in to.
+func makeRenameMap(from, to []*TypeParam) substMap {
+	assert(len(from) == len(to))
+	proj := make(substMap, len(from))
+	for i, tpar := range from {
+		proj[tpar] = to[i]
+	}
+	return proj
+}
+
 func (m substMap) empty() bool {
 	return len(m) == 0
 }
@@ -149,7 +160,10 @@ func (subst *subster) typ(typ Type) Type {
 		methods, mcopied := subst.funcList(t.methods)
 		embeddeds, ecopied := subst.typeList(t.embeddeds)
 		if mcopied || ecopied {
-			iface := &Interface{embeddeds: embeddeds, implicit: t.implicit, complete: t.complete}
+			iface := subst.check.newInterface()
+			iface.embeddeds = embeddeds
+			iface.implicit = t.implicit
+			iface.complete = t.complete
 			// If we've changed the interface type, we may need to replace its
 			// receiver if the receiver type is the original interface. Receivers of
 			// *Named type are replaced during named type expansion.

src/cmd/compile/internal/types2/termlist.go

@@ -92,15 +92,6 @@ func (xl termlist) norm() termlist {
 	return rl
 }
 
-// If the type set represented by xl is specified by a single (non-𝓤) term,
-// singleType returns that type. Otherwise it returns nil.
-func (xl termlist) singleType() Type {
-	if nl := xl.norm(); len(nl) == 1 {
-		return nl[0].typ // if nl.isAll() then typ is nil, which is ok
-	}
-	return nil
-}
-
 // union returns the union xl ∪ yl.
 func (xl termlist) union(yl termlist) termlist {
 	return append(xl, yl...).norm()

src/cmd/compile/internal/types2/termlist_test.go

@@ -106,35 +106,6 @@ func TestTermlistNorm(t *testing.T) {
 	}
 }
 
-func TestTermlistSingleType(t *testing.T) {
-	// helper to deal with nil types
-	tstring := func(typ Type) string {
-		if typ == nil {
-			return "nil"
-		}
-		return typ.String()
-	}
-
-	for test, want := range map[string]string{
-		"∅":                 "nil",
-		"𝓤":                 "nil",
-		"int":               "int",
-		"myInt":             "myInt",
-		"~int":              "int",
-		"~int ∪ string":     "nil",
-		"~int ∪ myInt":      "int",
-		"∅ ∪ int":           "int",
-		"∅ ∪ ~int":          "int",
-		"∅ ∪ ~int ∪ string": "nil",
-	} {
-		xl := maketl(test)
-		got := tstring(xl.singleType())
-		if got != want {
-			t.Errorf("(%v).singleType() == %v; want %v", test, got, want)
-		}
-	}
-}
-
 func TestTermlistUnion(t *testing.T) {
 	for _, test := range []struct {
 		xl, yl, want string

src/cmd/compile/internal/types2/testdata/check/builtins.go2

@@ -148,7 +148,7 @@ func _[
 	_ = make /* ERROR expects 2 or 3 arguments */ (S1)
 	_ = make(S1, 10, 20)
 	_ = make /* ERROR expects 2 or 3 arguments */ (S1, 10, 20, 30)
-	_ = make(S2 /* ERROR cannot make S2: no structural type */ , 10)
+	_ = make(S2 /* ERROR cannot make S2: no core type */ , 10)
 
 	type M0 map[string]int
 	_ = make(map[string]int)
@@ -156,7 +156,7 @@ func _[
 	_ = make(M1)
 	_ = make(M1, 10)
 	_ = make/* ERROR expects 1 or 2 arguments */(M1, 10, 20)
-	_ = make(M2 /* ERROR cannot make M2: no structural type */ )
+	_ = make(M2 /* ERROR cannot make M2: no core type */ )
 
 	type C0 chan int
 	_ = make(chan int)
@@ -164,7 +164,7 @@ func _[
 	_ = make(C1)
 	_ = make(C1, 10)
 	_ = make/* ERROR expects 1 or 2 arguments */(C1, 10, 20)
-	_ = make(C2 /* ERROR cannot make C2: no structural type */ )
+	_ = make(C2 /* ERROR cannot make C2: no core type */ )
 	_ = make(C3)
 }
 

src/cmd/compile/internal/types2/testdata/check/builtins.src

@@ -15,9 +15,9 @@ func append1() {
 	var x int
 	var s []byte
 	_ = append() // ERROR not enough arguments
-	_ = append("foo" /* ERROR not a slice */ )
+	_ = append("foo" /* ERROR must be a slice */ )
-	_ = append(nil /* ERROR not a slice */ , s)
+	_ = append(nil /* ERROR must be a slice */ , s)
-	_ = append(x /* ERROR not a slice */ , s)
+	_ = append(x /* ERROR must be a slice */ , s)
 	_ = append(s)
 	_ = append(s, nil...)
 	append /* ERROR not used */ (s)
@@ -77,7 +77,7 @@ func append3() {
 	_ = append(f2())
 	_ = append(f3())
 	_ = append(f5())
-	_ = append(ff /* ERROR not a slice */ ()) // TODO(gri) better error message
+	_ = append(ff /* ERROR must be a slice */ ()) // TODO(gri) better error message
 }
 
 func cap1() {

src/cmd/compile/internal/types2/testdata/check/funcinference.go2

@@ -8,21 +8,21 @@ import "strconv"
 
 type any interface{}
 
-func f0[A any, B interface{~*C}, C interface{~*D}, D interface{~*A}](A, B, C, D) {}
+func f0[A any, B interface{*C}, C interface{*D}, D interface{*A}](A, B, C, D) {}
 func _() {
 	f := f0[string]
 	f("a", nil, nil, nil)
 	f0("a", nil, nil, nil)
 }
 
-func f1[A any, B interface{~*A}](A, B) {}
+func f1[A any, B interface{*A}](A, B) {}
 func _() {
 	f := f1[int]
 	f(int(0), new(int))
 	f1(int(0), new(int))
 }
 
-func f2[A any, B interface{~[]A}](A, B) {}
+func f2[A any, B interface{[]A}](A, B) {}
 func _() {
 	f := f2[byte]
 	f(byte(0), []byte{})
@@ -38,7 +38,7 @@ func _() {
 // 	f3(x, &x, &x)
 // }
 
-func f4[A any, B interface{~[]C}, C interface{~*A}](A, B, C) {}
+func f4[A any, B interface{[]C}, C interface{*A}](A, B, C) {}
 func _() {
 	f := f4[int]
 	var x int
@@ -46,7 +46,7 @@ func _() {
 	f4(x, []*int{}, &x)
 }
 
-func f5[A interface{~struct{b B; c C}}, B any, C interface{~*B}](x B) A { panic(0) }
+func f5[A interface{struct{b B; c C}}, B any, C interface{*B}](x B) A { panic(0) }
 func _() {
 	x := f5(1.2)
 	var _ float64 = x.b
@@ -79,14 +79,14 @@ var _ = Double(MySlice{1})
 
 type Setter[B any] interface {
 	Set(string)
-	~*B
+	*B
 }
 
 func FromStrings[T interface{}, PT Setter[T]](s []string) []T {
 	result := make([]T, len(s))
 	for i, v := range s {
 		// The type of &result[i] is *T which is in the type list
-		// of Setter2, so we can convert it to PT.
+		// of Setter, so we can convert it to PT.
 		p := PT(&result[i])
 		// PT has a Set method.
 		p.Set(v)

src/cmd/compile/internal/types2/testdata/check/typeinference.go2

@@ -4,44 +4,46 @@
 
 package typeInference
 
+// As of issue #51527, type-type inference has been disabled.
+
 // basic inference
 type Tb[P ~*Q, Q any] int
 func _() {
-	var x Tb[*int]
+	var x Tb /* ERROR got 1 arguments */ [*int]
 	var y Tb[*int, int]
-	x = y
+	x = y /* ERROR cannot use y .* in assignment */
 	_ = x
 }
 
 // recursive inference
-type Tr[A any, B ~*C, C ~*D, D ~*A] int
+type Tr[A any, B *C, C *D, D *A] int
 func _() {
-	var x Tr[string]
+	var x Tr /* ERROR got 1 arguments */ [string]
 	var y Tr[string, ***string, **string, *string]
 	var z Tr[int, ***int, **int, *int]
-	x = y
+	x = y /* ERROR cannot use y .* in assignment */
 	x = z // ERROR cannot use z .* as Tr
 	_ = x
 }
 
 // other patterns of inference
-type To0[A any, B ~[]A] int
+type To0[A any, B []A] int
-type To1[A any, B ~struct{a A}] int
+type To1[A any, B struct{a A}] int
-type To2[A any, B ~[][]A] int
+type To2[A any, B [][]A] int
-type To3[A any, B ~[3]*A] int
+type To3[A any, B [3]*A] int
-type To4[A any, B any, C ~struct{a A; b B}] int
+type To4[A any, B any, C struct{a A; b B}] int
 func _() {
-	var _ To0[int]
+	var _ To0 /* ERROR got 1 arguments */ [int]
-	var _ To1[int]
+	var _ To1 /* ERROR got 1 arguments */ [int]
-	var _ To2[int]
+	var _ To2 /* ERROR got 1 arguments */ [int]
-	var _ To3[int]
+	var _ To3 /* ERROR got 1 arguments */ [int]
-	var _ To4[int, string]
+	var _ To4 /* ERROR got 2 arguments */ [int, string]
 }
 
 // failed inference
 type Tf0[A, B any] int
 type Tf1[A any, B ~struct{a A; c C}, C any] int
 func _() {
-	var _ Tf0 /* ERROR cannot infer B */ /* ERROR got 1 arguments but 2 type parameters */ [int]
+	var _ Tf0 /* ERROR got 1 arguments but 2 type parameters */ [int]
-	var _ Tf1 /* ERROR cannot infer B */ /* ERROR got 1 arguments but 3 type parameters */ [int]
+	var _ Tf1 /* ERROR got 1 arguments but 3 type parameters */ [int]
 }

src/cmd/compile/internal/types2/testdata/check/typeparams.go2

@@ -134,11 +134,11 @@ func _[T interface{ ~string }] (x T, i, j, k int) { var _ T = x[i:j:k /* ERROR 3
 type myByte1 []byte
 type myByte2 []byte
 func _[T interface{ []byte | myByte1 | myByte2 }] (x T, i, j, k int) { var _ T = x[i:j:k] }
-func _[T interface{ []byte | myByte1 | []int }] (x T, i, j, k int) { var _ T = x[ /* ERROR no structural type */ i:j:k] }
+func _[T interface{ []byte | myByte1 | []int }] (x T, i, j, k int) { var _ T = x[ /* ERROR no core type */ i:j:k] }
 
 func _[T interface{ []byte | myByte1 | myByte2 | string }] (x T, i, j, k int) { var _ T = x[i:j] }
 func _[T interface{ []byte | myByte1 | myByte2 | string }] (x T, i, j, k int) { var _ T = x[i:j:k /* ERROR 3-index slice of string */ ] }
-func _[T interface{ []byte | myByte1 | []int | string }] (x T, i, j, k int) { var _ T = x[ /* ERROR no structural type */ i:j] }
+func _[T interface{ []byte | myByte1 | []int | string }] (x T, i, j, k int) { var _ T = x[ /* ERROR no core type */ i:j] }
 
 // len/cap built-ins
 
@@ -230,7 +230,7 @@ func _[
         for _, _ = range s1 {}
 
         var s2 S2
-        for range s2 /* ERROR cannot range over s2.*no structural type */ {}
+        for range s2 /* ERROR cannot range over s2.*no core type */ {}
 
         var a0 []int
         for range a0 {}
@@ -243,7 +243,7 @@ func _[
         for _, _ = range a1 {}
 
         var a2 A2
-        for range a2 /* ERROR cannot range over a2.*no structural type */ {}
+        for range a2 /* ERROR cannot range over a2.*no core type */ {}
 
         var p0 *[10]int
         for range p0 {}
@@ -256,7 +256,7 @@ func _[
         for _, _ = range p1 {}
 
         var p2 P2
-        for range p2 /* ERROR cannot range over p2.*no structural type */ {}
+        for range p2 /* ERROR cannot range over p2.*no core type */ {}
 
         var m0 map[string]int
         for range m0 {}
@@ -269,7 +269,7 @@ func _[
         for _, _ = range m1 {}
 
         var m2 M2
-        for range m2 /* ERROR cannot range over m2.*no structural type */ {}
+        for range m2 /* ERROR cannot range over m2.*no core type */ {}
 }
 
 // type inference checks

src/cmd/compile/internal/types2/testdata/examples/inference.go2

@@ -78,7 +78,7 @@ func _() {
 	related1(si, "foo" /* ERROR cannot use "foo" */ )
 }
 
-func related2[Elem any, Slice interface{~[]Elem}](e Elem, s Slice) {}
+func related2[Elem any, Slice interface{[]Elem}](e Elem, s Slice) {}
 
 func _() {
 	// related2 can be called with explicit instantiation.
@@ -109,16 +109,8 @@ func _() {
 	related3[int, []int]()
 	related3[byte, List[byte]]()
 
-	// Alternatively, the 2nd type argument can be inferred
+	// The 2nd type argument cannot be inferred from the first
-	// from the first one through constraint type inference.
+	// one because there's two possible choices: []Elem and
-	related3[int]()
+	// List[Elem].
-
+	related3[int]( /* ERROR cannot infer Slice */ )
-	// The inferred type is the structural type of the Slice
-	// type parameter.
-	var _ []int = related3[int]()
-
-	// It is not the defined parameterized type List.
-	type anotherList []float32
-	var _ anotherList = related3[float32]() // valid
-	var _ anotherList = related3 /* ERROR cannot use .* \(value of type List\[float32\]\) as anotherList */ [float32, List[float32]]()
 }

src/cmd/compile/internal/types2/testdata/examples/methods.go2

@@ -35,7 +35,7 @@ func (t T1[[ /* ERROR must be an identifier */ ]int]) m2() {}
 // style. In m3 below, int is the name of the local receiver type parameter
 // and it shadows the predeclared identifier int which then cannot be used
 // anymore as expected.
-// This is no different from locally redelaring a predeclared identifier
+// This is no different from locally re-declaring a predeclared identifier
 // and usually should be avoided. There are some notable exceptions; e.g.,
 // sometimes it makes sense to use the identifier "copy" which happens to
 // also be the name of a predeclared built-in function.

src/cmd/compile/internal/types2/testdata/examples/types.go2

@@ -292,7 +292,7 @@ func _[T interface{~int|~float64}]() {
 
 // It is possible to create composite literals of type parameter
 // type as long as it's possible to create a composite literal
-// of the structural type of the type parameter's constraint.
+// of the core type of the type parameter's constraint.
 func _[P interface{ ~[]int }]() P {
 	return P{}
 	return P{1, 2, 3}
@@ -307,7 +307,7 @@ func _[P interface{ ~[]E }, E interface{ map[string]P } ]() P {
 }
 
 // This is a degenerate case with a singleton type set, but we can create
-// composite literals even if the structural type is a defined type.
+// composite literals even if the core type is a defined type.
 type MyInts []int
 
 func _[P MyInts]() P {

src/cmd/compile/internal/types2/testdata/examples/typesets.go2

@@ -35,7 +35,7 @@ func _() int {
 	return deref(p)
 }
 
-func addrOfCopy[V any, P ~*V](v V) P {
+func addrOfCopy[V any, P *V](v V) P {
 	return &v
 }
 

src/cmd/compile/internal/types2/testdata/fixedbugs/issue41124.go2

@@ -47,7 +47,7 @@ type _ struct{
 }
 
 type _ struct{
-	I3 // ERROR interface is .* comparable
+	I3 // ERROR interface contains type constraints
 }
 
 // General composite types.
@@ -59,19 +59,19 @@ type (
 	_ []I1 // ERROR interface is .* comparable
 	_ []I2 // ERROR interface contains type constraints
 
-	_ *I3 // ERROR interface is .* comparable
+	_ *I3 // ERROR interface contains type constraints
 	_ map[I1 /* ERROR interface is .* comparable */ ]I2 // ERROR interface contains type constraints
-	_ chan I3 // ERROR interface is .* comparable
+	_ chan I3 // ERROR interface contains type constraints
 	_ func(I1 /* ERROR interface is .* comparable */ )
 	_ func() I2 // ERROR interface contains type constraints
 )
 
 // Other cases.
 
-var _ = [...]I3 /* ERROR interface is .* comparable */ {}
+var _ = [...]I3 /* ERROR interface contains type constraints */ {}
 
 func _(x interface{}) {
-	_ = x.(I3 /* ERROR interface is .* comparable */ )
+	_ = x.(I3 /* ERROR interface contains type constraints */ )
 }
 
 type T1[_ any] struct{}

src/cmd/compile/internal/types2/testdata/fixedbugs/issue43527.go2

@@ -9,7 +9,7 @@ const L = 10
 type (
 	_        [L]struct{}
 	_        [A /* ERROR undeclared name A for array length */ ]struct{}
-	_        [B /* ERROR not an expression */ ]struct{}
+	_        [B /* ERROR invalid array length B */ ]struct{}
 	_[A any] struct{}
 
 	B int

src/cmd/compile/internal/types2/testdata/fixedbugs/issue43671.go2

@@ -12,7 +12,7 @@ type C4 interface{ chan int | chan<- int }
 type C5[T any] interface{ ~chan T | <-chan T }
 
 func _[T any](ch T) {
-	<-ch // ERROR cannot receive from ch .* no structural type
+	<-ch // ERROR cannot receive from ch .* no core type
 }
 
 func _[T C0](ch T) {
@@ -28,7 +28,7 @@ func _[T C2](ch T) {
 }
 
 func _[T C3](ch T) {
-	<-ch // ERROR cannot receive from ch .* no structural type
+	<-ch // ERROR cannot receive from ch .* no core type
 }
 
 func _[T C4](ch T) {

src/cmd/compile/internal/types2/testdata/fixedbugs/issue45548.go2

@@ -4,7 +4,7 @@
 
 package p
 
-func f[F interface{~*Q}, G interface{~*R}, Q, R any](q Q, r R) {}
+func f[F interface{*Q}, G interface{*R}, Q, R any](q Q, r R) {}
 
 func _() {
 	f[*float64, *int](1, 2)

src/cmd/compile/internal/types2/testdata/fixedbugs/issue47115.go2

@@ -12,7 +12,7 @@ type C4 interface{ chan int | chan<- int }
 type C5[T any] interface{ ~chan T | chan<- T }
 
 func _[T any](ch T) {
-	ch /* ERROR cannot send to ch .* no structural type */ <- 0
+	ch /* ERROR cannot send to ch .* no core type */ <- 0
 }
 
 func _[T C0](ch T) {
@@ -28,7 +28,7 @@ func _[T C2](ch T) {
 }
 
 func _[T C3](ch T) {
-	ch /* ERROR cannot send to ch .* no structural type */ <- 0
+	ch /* ERROR cannot send to ch .* no core type */ <- 0
 }
 
 func _[T C4](ch T) {

src/cmd/compile/internal/types2/testdata/fixedbugs/issue47818.go2

@@ -8,13 +8,13 @@
 
 package go1_17
 
-type T[P /* ERROR type parameters require go1\.18 or later */ any /* ERROR undeclared name: any \(requires version go1\.18 or later\) */ ] struct{}
+type T[P /* ERROR type parameter requires go1\.18 or later */ any /* ERROR undeclared name: any \(requires version go1\.18 or later\) */ ] struct{}
 
 // for init (and main, but we're not in package main) we should only get one error
 func init[P /* ERROR func init must have no type parameters */ any /* ERROR undeclared name: any \(requires version go1\.18 or later\) */ ]()   {}
-func main[P /* ERROR type parameters require go1\.18 or later */ any /* ERROR undeclared name: any \(requires version go1\.18 or later\) */ ]() {}
+func main[P /* ERROR type parameter requires go1\.18 or later */ any /* ERROR undeclared name: any \(requires version go1\.18 or later\) */ ]() {}
 
-func f[P /* ERROR type parameters require go1\.18 or later */ any /* ERROR undeclared name: any \(requires version go1\.18 or later\) */ ](x P) {
+func f[P /* ERROR type parameter requires go1\.18 or later */ any /* ERROR undeclared name: any \(requires version go1\.18 or later\) */ ](x P) {
 	var _ T[ /* ERROR type instantiation requires go1\.18 or later */ int]
 	var _ (T[ /* ERROR type instantiation requires go1\.18 or later */ int])
 	_ = T[ /* ERROR type instantiation requires go1\.18 or later */ int]{}

src/cmd/compile/internal/types2/testdata/fixedbugs/issue48619.go2

@@ -2,24 +2,19 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// This issue is still open:
-// - the error messages could be better or are incorrect
-// - unification fails due to stack overflow that is caught
-
 package p
 
 func f[P any](a, _ P) {
 	var x int
 	// TODO(gri) these error messages, while correct, could be better
-	f(a, x /* ERROR type int of x does not match P */)
+	f(a, x /* ERROR type int of x does not match inferred type P for P */)
 	f(x, a /* ERROR type P of a does not match inferred type int for P */)
 }
 
 func g[P any](a, b P) {
 	g(a, b)
-	// TODO(gri) these error messages are incorrect because the code is valid
+	g(&a, &b)
-	g(&a, & /* ERROR type \*P of &b does not match inferred type \*P for P */ b)
+	g([]P{}, []P{})
-	g([]P{}, [ /* ERROR type \[\]P of \[\]P{} does not match inferred type \[\]P for P */ ]P{})
 
 	// work-around: provide type argument explicitly
 	g[*P](&a, &b)

src/cmd/compile/internal/types2/testdata/fixedbugs/issue48656.go2

@@ -2,14 +2,12 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// This issue is still open:
-// - the error messages are unclear
-// - unification fails due to stack overflow that is caught
-
 package p
 
 func f[P *Q, Q any](P, Q) {
-	// TODO(gri) these error messages are unclear
+	_ = f[P]
-	_ = f[ /* ERROR P does not match \*Q */ P]
+}
-	_ = f[ /* ERROR cannot infer P */ *P]
+
+func f2[P /* ERROR instantiation cycle */ *Q, Q any](P, Q) {
+	_ = f2[*P]
 }

src/cmd/compile/internal/types2/testdata/fixedbugs/issue49482.go2

@@ -0,0 +1,25 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file is tested when running "go test -run Manual"
+// without source arguments. Use for one-off debugging.
+
+package p
+
+// The following is OK, per the special handling for type literals discussed in issue #49482.
+type _[P *struct{}] struct{}
+type _[P *int,] int
+type _[P (*int),] int
+
+const P = 2 // declare P to avoid noisy 'undeclared name' errors below.
+
+// The following parse as invalid array types.
+type _[P *int /* ERROR "int \(type\) is not an expression" */ ] int
+type _[P /* ERROR non-function P */ (*int)] int
+
+// The following should be parsed as a generic type, but is instead parsed as an array type.
+type _[P *struct /* ERROR "not an expression" */ {}| int /* ERROR "not an expression" */ ] struct{}
+
+// The following fails to parse, due to the '~'
+type _[P *struct /* ERROR "not an expression" */ {}|~ /* ERROR "unexpected ~" */ int] struct{}

src/cmd/compile/internal/types2/testdata/fixedbugs/issue49541.go2

@@ -10,9 +10,10 @@ type S[A, B any] struct {
 
 func (S[A, B]) m() {}
 
-// TODO(gri) We should only report one error below. See issue #50588.
+// TODO(gri): with type-type inference enabled we should only report one error
+// below. See issue #50588.
 
-func _[A any](s S /* ERROR cannot infer B */ /* ERROR got 1 arguments but 2 type parameters */ [A]) {
+func _[A any](s S /* ERROR got 1 arguments but 2 type parameters */ [A]) {
 	// we should see no follow-on errors below
 	s.f = 1
 	s.m()
@@ -21,7 +22,7 @@ func _[A any](s S /* ERROR cannot infer B */ /* ERROR got 1 arguments but 2 type
 // another test case from the issue
 
 func _() {
-	X(Interface[*F /* ERROR cannot infer B */ /* ERROR got 1 arguments but 2 type parameters */ [string]](Impl{}))
+	X(Interface[*F /* ERROR got 1 arguments but 2 type parameters */ [string]](Impl{}))
 }
 
 func X[Q Qer](fs Interface[Q]) {

src/cmd/compile/internal/types2/testdata/fixedbugs/issue49735.go2

@@ -0,0 +1,11 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+func _[P1 any, P2 ~byte](s1 P1, s2 P2) {
+        _ = append(nil /* ERROR first argument to append must be a slice; have untyped nil */ , 0)
+        _ = append(s1 /* ERROR s1 .* has no core type */ , 0)
+        _ = append(s2 /* ERROR s2 .* has core type byte */ , 0)
+}

src/cmd/compile/internal/types2/testdata/fixedbugs/issue50417.go2

@@ -2,6 +2,10 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Field accesses through type parameters are disabled
+// until we have a more thorough understanding of the
+// implications on the spec. See issue #51576.
+
 package p
 
 type Sf struct {
@@ -9,13 +13,13 @@ type Sf struct {
 }
 
 func f0[P Sf](p P) {
-        _ = p.f
+        _ = p.f // ERROR p\.f undefined
-        p.f = 0
+        p.f /* ERROR p\.f undefined */ = 0
 }
 
 func f0t[P ~struct{f int}](p P) {
-        _ = p.f
+        _ = p.f // ERROR p\.f undefined
-        p.f = 0
+        p.f /* ERROR p\.f undefined */ = 0
 }
 
 var _ = f0[Sf]
@@ -25,8 +29,8 @@ var _ = f0[Sm /* ERROR does not implement */ ]
 var _ = f0t[Sm /* ERROR does not implement */ ]
 
 func f1[P interface{ Sf; m() }](p P) {
-        _ = p.f
+        _ = p.f // ERROR p\.f undefined
-        p.f = 0
+        p.f /* ERROR p\.f undefined */ = 0
         p.m()
 }
 
@@ -44,20 +48,20 @@ type Sfm struct {
 func (Sfm) m() {}
 
 func f2[P interface{ Sfm; m() }](p P) {
-        _ = p.f
+        _ = p.f // ERROR p\.f undefined
-        p.f = 0
+        p.f /* ERROR p\.f undefined */ = 0
         p.m()
 }
 
 var _ = f2[Sfm]
 
-// special case: structural type is a named pointer type
+// special case: core type is a named pointer type
 
 type PSfm *Sfm
 
 func f3[P interface{ PSfm }](p P) {
-        _ = p.f
+        _ = p.f // ERROR p\.f undefined
-        p.f = 0
+        p.f /* ERROR p\.f undefined */ = 0
         p.m /* ERROR type P has no field or method m */ ()
 }
 

src/cmd/compile/internal/types2/testdata/fixedbugs/issue50755.go2

@@ -0,0 +1,47 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+// The core type of M2 unifies with the type of m1
+// during function argument type inference.
+// M2's constraint is unnamed.
+func f1[K1 comparable, E1 any](m1 map[K1]E1) {}
+
+func f2[M2 map[string]int](m2 M2) {
+	f1(m2)
+}
+
+// The core type of M3 unifies with the type of m1
+// during function argument type inference.
+// M3's constraint is named.
+type Map3 map[string]int
+
+func f3[M3 Map3](m3 M3) {
+	f1(m3)
+}
+
+// The core type of M5 unifies with the core type of M4
+// during constraint type inference.
+func f4[M4 map[K4]int, K4 comparable](m4 M4) {}
+
+func f5[M5 map[K5]int, K5 comparable](m5 M5) {
+	f4(m5)
+}
+
+// test case from issue
+
+func Copy[MC ~map[KC]VC, KC comparable, VC any](dst, src MC) {
+	for k, v := range src {
+		dst[k] = v
+	}
+}
+
+func Merge[MM ~map[KM]VM, KM comparable, VM any](ms ...MM) MM {
+	result := MM{}
+	for _, m := range ms {
+		Copy(result, m)
+	}
+	return result
+}

src/cmd/compile/internal/types2/testdata/fixedbugs/issue50782.go2

@@ -2,6 +2,10 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Field accesses through type parameters are disabled
+// until we have a more thorough understanding of the
+// implications on the spec. See issue #51576.
+
 package p
 
 // The first example from the issue.
@@ -18,9 +22,12 @@ type numericAbs[T Numeric] interface {
 // AbsDifference computes the absolute value of the difference of
 // a and b, where the absolute value is determined by the Abs method.
 func absDifference[T numericAbs[T /* ERROR T does not implement Numeric */]](a, b T) T {
-	// TODO: the error below should probably be positioned on the '-'.
+	// Field accesses are not permitted for now. Keep an error so
-	d := a /* ERROR "invalid operation: operator - not defined" */ .Value - b.Value
+	// we can find and fix this code once the situation changes.
-	return d.Abs()
+	return a.Value // ERROR a\.Value undefined
+	// TODO: The error below should probably be positioned on the '-'.
+	// d := a /* ERROR "invalid operation: operator - not defined" */ .Value - b.Value
+	// return d.Abs()
 }
 
 // The second example from the issue.

src/cmd/compile/internal/types2/testdata/fixedbugs/issue50929.go2

@@ -16,7 +16,7 @@ func G[A, B any](F[A, B]) {
 
 func _() {
 	// TODO(gri) only report one error below (issue #50932)
-	var x F /* ERROR cannot infer B */ /* ERROR got 1 arguments but 2 type parameters */ [int]
+	var x F /* ERROR got 1 arguments but 2 type parameters */ [int]
 	G(x /* ERROR does not match */)
 }
 
@@ -46,9 +46,9 @@ func NSG[G any](c RSC[G]) {
 	fmt.Println(c)
 }
 
-func MMD[Rc RC /* ERROR cannot infer RG */ /* ERROR got 1 arguments */ [RG], RG any, G any]() M /* ERROR got 2 arguments */ /* ERROR Rc does not match */ [Rc, RG] {
+func MMD[Rc RC /* ERROR got 1 arguments */ [RG], RG any, G any]() M /* ERROR got 2 arguments */ [Rc, RG] {
 
-	var nFn NFn /* ERROR got 2 arguments */ /* ERROR Rc does not match */ [Rc, RG]
+	var nFn NFn /* ERROR got 2 arguments */ [Rc, RG]
 
 	var empty Rc
 	switch any(empty).(type) {

src/cmd/compile/internal/types2/testdata/fixedbugs/issue51145.go

@@ -0,0 +1,18 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+import "fmt"
+
+type (
+	_ [fmt /* ERROR invalid array length fmt */ ]int
+	_ [float64 /* ERROR invalid array length float64 */ ]int
+	_ [f /* ERROR invalid array length f */ ]int
+	_ [nil /* ERROR invalid array length nil */ ]int
+)
+
+func f()
+
+var _ fmt.Stringer // use fmt

src/cmd/compile/internal/types2/testdata/fixedbugs/issue51158.go2

@@ -0,0 +1,18 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+// Type checking the following code should not cause an infinite recursion.
+func f[M map[K]int, K comparable](m M) {
+        f(m)
+}
+
+// Equivalent code using mutual recursion.
+func f1[M map[K]int, K comparable](m M) {
+        f2(m)
+}
+func f2[M map[K]int, K comparable](m M) {
+        f1(m)
+}

src/cmd/compile/internal/types2/testdata/fixedbugs/issue51229.go2

@@ -0,0 +1,164 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+// Constraint type inference should be independent of the
+// ordering of the type parameter declarations. Try all
+// permutations in the test case below.
+// Permutations produced by https://go.dev/play/p/PHcZNGJTEBZ.
+
+func f00[S1 ~[]E1, S2 ~[]E2, E1 ~byte, E2 ~byte](S1, S2) {}
+func f01[S2 ~[]E2, S1 ~[]E1, E1 ~byte, E2 ~byte](S1, S2) {}
+func f02[E1 ~byte, S1 ~[]E1, S2 ~[]E2, E2 ~byte](S1, S2) {}
+func f03[S1 ~[]E1, E1 ~byte, S2 ~[]E2, E2 ~byte](S1, S2) {}
+func f04[S2 ~[]E2, E1 ~byte, S1 ~[]E1, E2 ~byte](S1, S2) {}
+func f05[E1 ~byte, S2 ~[]E2, S1 ~[]E1, E2 ~byte](S1, S2) {}
+func f06[E2 ~byte, S2 ~[]E2, S1 ~[]E1, E1 ~byte](S1, S2) {}
+func f07[S2 ~[]E2, E2 ~byte, S1 ~[]E1, E1 ~byte](S1, S2) {}
+func f08[S1 ~[]E1, E2 ~byte, S2 ~[]E2, E1 ~byte](S1, S2) {}
+func f09[E2 ~byte, S1 ~[]E1, S2 ~[]E2, E1 ~byte](S1, S2) {}
+func f10[S2 ~[]E2, S1 ~[]E1, E2 ~byte, E1 ~byte](S1, S2) {}
+func f11[S1 ~[]E1, S2 ~[]E2, E2 ~byte, E1 ~byte](S1, S2) {}
+func f12[S1 ~[]E1, E1 ~byte, E2 ~byte, S2 ~[]E2](S1, S2) {}
+func f13[E1 ~byte, S1 ~[]E1, E2 ~byte, S2 ~[]E2](S1, S2) {}
+func f14[E2 ~byte, S1 ~[]E1, E1 ~byte, S2 ~[]E2](S1, S2) {}
+func f15[S1 ~[]E1, E2 ~byte, E1 ~byte, S2 ~[]E2](S1, S2) {}
+func f16[E1 ~byte, E2 ~byte, S1 ~[]E1, S2 ~[]E2](S1, S2) {}
+func f17[E2 ~byte, E1 ~byte, S1 ~[]E1, S2 ~[]E2](S1, S2) {}
+func f18[E2 ~byte, E1 ~byte, S2 ~[]E2, S1 ~[]E1](S1, S2) {}
+func f19[E1 ~byte, E2 ~byte, S2 ~[]E2, S1 ~[]E1](S1, S2) {}
+func f20[S2 ~[]E2, E2 ~byte, E1 ~byte, S1 ~[]E1](S1, S2) {}
+func f21[E2 ~byte, S2 ~[]E2, E1 ~byte, S1 ~[]E1](S1, S2) {}
+func f22[E1 ~byte, S2 ~[]E2, E2 ~byte, S1 ~[]E1](S1, S2) {}
+func f23[S2 ~[]E2, E1 ~byte, E2 ~byte, S1 ~[]E1](S1, S2) {}
+
+type myByte byte
+
+func _(a []byte, b []myByte) {
+	f00(a, b)
+	f01(a, b)
+	f02(a, b)
+	f03(a, b)
+	f04(a, b)
+	f05(a, b)
+	f06(a, b)
+	f07(a, b)
+	f08(a, b)
+	f09(a, b)
+	f10(a, b)
+	f11(a, b)
+	f12(a, b)
+	f13(a, b)
+	f14(a, b)
+	f15(a, b)
+	f16(a, b)
+	f17(a, b)
+	f18(a, b)
+	f19(a, b)
+	f20(a, b)
+	f21(a, b)
+	f22(a, b)
+	f23(a, b)
+}
+
+// Constraint type inference may have to iterate.
+// Again, the order of the type parameters shouldn't matter.
+
+func g0[S ~[]E, M ~map[string]S, E any](m M) {}
+func g1[M ~map[string]S, S ~[]E, E any](m M) {}
+func g2[E any, S ~[]E, M ~map[string]S](m M) {}
+func g3[S ~[]E, E any, M ~map[string]S](m M) {}
+func g4[M ~map[string]S, E any, S ~[]E](m M) {}
+func g5[E any, M ~map[string]S, S ~[]E](m M) {}
+
+func _(m map[string][]byte) {
+	g0(m)
+	g1(m)
+	g2(m)
+	g3(m)
+	g4(m)
+	g5(m)
+}
+
+// Worst-case scenario.
+// There are 10 unknown type parameters. In each iteration of
+// constraint type inference we infer one more, from right to left.
+// Each iteration looks repeatedly at all 11 type parameters,
+// requiring a total of 10*11 = 110 iterations with the current
+// implementation. Pathological case.
+
+func h[K any, J ~*K, I ~*J, H ~*I, G ~*H, F ~*G, E ~*F, D ~*E, C ~*D, B ~*C, A ~*B](x A) {}
+
+func _(x **********int) {
+	h(x)
+}
+
+// Examples with channel constraints and tilde.
+
+func ch1[P chan<- int]() (_ P)           { return } // core(P) == chan<- int   (single type, no tilde)
+func ch2[P ~chan int]()                  { return } // core(P) == ~chan<- int  (tilde)
+func ch3[P chan E, E any](E)             { return } // core(P) == chan<- E     (single type, no tilde)
+func ch4[P chan E | ~chan<- E, E any](E) { return } // core(P) == ~chan<- E    (tilde)
+func ch5[P chan int | chan<- int]()      { return } // core(P) == chan<- int   (not a single type)
+
+func _() {
+	// P can be inferred as there's a single specific type and no tilde.
+	var _ chan int = ch1 /* ERROR cannot use ch1.*value of type chan<- int */ ()
+	var _ chan<- int = ch1()
+
+	// P cannot be inferred as there's a tilde.
+	ch2( /* ERROR cannot infer P */ )
+	type myChan chan int
+	ch2[myChan]()
+
+	// P can be inferred as there's a single specific type and no tilde.
+	var e int
+	ch3(e)
+
+	// P cannot be inferred as there's more than one specific type and a tilde.
+	ch4( /* ERROR cannot infer P */ e)
+	_ = ch4[chan int]
+
+	// P cannot be inferred as there's more than one specific type.
+	ch5( /* ERROR cannot infer P */ )
+	ch5[chan<- int]()
+}
+
+// test case from issue
+
+func equal[M1 ~map[K1]V1, M2 ~map[K2]V2, K1, K2 ~uint32, V1, V2 ~string](m1 M1, m2 M2) bool {
+	if len(m1) != len(m2) {
+		return false
+	}
+	for k, v1 := range m1 {
+		if v2, ok := m2[K2(k)]; !ok || V2(v1) != v2 {
+			return false
+		}
+	}
+	return true
+}
+
+func equalFixed[K1, K2 ~uint32, V1, V2 ~string](m1 map[K1]V1, m2 map[K2]V2) bool {
+	if len(m1) != len(m2) {
+		return false
+	}
+	for k, v1 := range m1 {
+		if v2, ok := m2[K2(k)]; !ok || v1 != V1(v2) {
+			return false
+		}
+	}
+	return true
+}
+
+type (
+	someNumericID uint32
+	someStringID  string
+)
+
+func _() {
+	foo := map[uint32]string{10: "bar"}
+	bar := map[someNumericID]someStringID{10: "bar"}
+	equal(foo, bar)
+}

src/cmd/compile/internal/types2/testdata/fixedbugs/issue51232.go2

@@ -0,0 +1,30 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type RC[RG any] interface {
+	~[]RG
+}
+
+type Fn[RCT RC[RG], RG any] func(RCT)
+
+type F[RCT RC[RG], RG any] interface {
+	Fn() Fn /* ERROR got 1 arguments */ [RCT]
+}
+
+type concreteF[RCT RC[RG], RG any] struct {
+	makeFn func() Fn /* ERROR got 1 arguments */ [RCT]
+}
+
+func (c *concreteF[RCT, RG]) Fn() Fn /* ERROR got 1 arguments */ [RCT] {
+	return c.makeFn()
+}
+
+func NewConcrete[RCT RC[RG], RG any](Rc RCT) F /* ERROR got 1 arguments */ [RCT] {
+	// TODO(rfindley): eliminate the duplicate error below.
+	return & /* ERROR cannot use .* as F\[RCT\] */ concreteF /* ERROR got 1 arguments */ [RCT]{
+		makeFn: nil,
+	}
+}

src/cmd/compile/internal/types2/testdata/fixedbugs/issue51233.go2

@@ -0,0 +1,27 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+// As of issue #51527, type-type inference has been disabled.
+
+type RC[RG any] interface {
+	~[]RG
+}
+
+type Fn[RCT RC[RG], RG any] func(RCT)
+
+type FFn[RCT RC[RG], RG any] func() Fn /* ERROR got 1 arguments */ [RCT]
+
+type F[RCT RC[RG], RG any] interface {
+	Fn() Fn /* ERROR got 1 arguments */ [RCT]
+}
+
+type concreteF[RCT RC[RG], RG any] struct {
+	makeFn FFn /* ERROR got 1 arguments */ [RCT]
+}
+
+func (c *concreteF[RCT, RG]) Fn() Fn /* ERROR got 1 arguments */ [RCT] {
+	return c.makeFn()
+}

src/cmd/compile/internal/types2/testdata/fixedbugs/issue51257.go2

@@ -0,0 +1,46 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+func f[_ comparable]() {}
+
+type S1 struct{ x int }
+type S2 struct{ x any }
+type S3 struct{ x [10]interface{ m() } }
+
+func _[P1 comparable, P2 S2]() {
+	_ = f[S1]
+	_ = f[S2 /* ERROR S2 does not implement comparable */ ]
+	_ = f[S3 /* ERROR S3 does not implement comparable */ ]
+
+	type L1 struct { x P1 }
+	type L2 struct { x P2 }
+	_ = f[L1]
+	_ = f[L2 /* ERROR L2 does not implement comparable */ ]
+}
+
+
+// example from issue
+
+type Set[T comparable] map[T]struct{}
+
+func NewSetFromSlice[T comparable](items []T) *Set[T] {
+	s := Set[T]{}
+
+	for _, item := range items {
+		s[item] = struct{}{}
+	}
+
+	return &s
+}
+
+type T struct{ x any }
+
+func main() {
+	NewSetFromSlice( /* ERROR T does not implement comparable */ []T{
+		{"foo"},
+		{5},
+	})
+}

src/cmd/compile/internal/types2/testdata/fixedbugs/issue51335.go2

@@ -0,0 +1,16 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type S1 struct{}
+type S2 struct{}
+
+func _[P *S1|*S2]() {
+	_= []P{{ /* ERROR invalid composite literal element type P: no core type */ }}
+}
+
+func _[P *S1|S1]() {
+	_= []P{{ /* ERROR invalid composite literal element type P: no core type */ }}
+}

src/cmd/compile/internal/types2/testdata/fixedbugs/issue51339.go2

@@ -0,0 +1,18 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file is tested when running "go test -run Manual"
+// without source arguments. Use for one-off debugging.
+
+package p
+
+type T[P any, B *P] struct{}
+
+func (T /* ERROR cannot use generic type */ ) m0() {}
+
+// TODO(rfindley): eliminate the duplicate errors here.
+func (T /* ERROR got 1 type parameter, but receiver base type declares 2 */ /* ERROR got 1 arguments but 2 type parameters */ [_]) m1() {}
+func (T[_, _]) m2() {}
+// TODO(gri) this error is unfortunate (issue #51343)
+func (T /* ERROR got 3 arguments but 2 type parameters */ [_, _, _]) m3() {}

src/cmd/compile/internal/types2/testdata/fixedbugs/issue51360.go

@@ -0,0 +1,13 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+func _() {
+	len. /* ERROR cannot select on len */ Println
+	len. /* ERROR cannot select on len */ Println()
+	_ = len. /* ERROR cannot select on len */ Println
+	_ = len[ /* ERROR cannot index len */ 0]
+	_ = *len /* ERROR cannot indirect len */
+}

src/cmd/compile/internal/types2/testdata/fixedbugs/issue51376.go2

@@ -0,0 +1,24 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type Map map[string]int
+
+func f[M ~map[K]V, K comparable, V any](M) {}
+func g[M map[K]V, K comparable, V any](M) {}
+
+func _[M1 ~map[K]V, M2 map[K]V, K comparable, V any]() {
+        var m1 M1
+        f(m1)
+        g( /* ERROR M1 does not implement map\[K\]V */ m1) // M1 has tilde
+
+        var m2 M2
+        f(m2)
+        g(m2) // M1 does not have tilde
+
+        var m3 Map
+        f(m3)
+        g( /* ERROR Map does not implement map\[string\]int */ m3) // M in g does not have tilde
+}

src/cmd/compile/internal/types2/testdata/fixedbugs/issue51386.go2

@@ -0,0 +1,17 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type myString string
+
+func _[P ~string | ~[]byte | ~[]rune]() {
+	_ = P("")
+	const s myString = ""
+	_ = P(s)
+}
+
+func _[P myString]() {
+	_ = P("")
+}

src/cmd/compile/internal/types2/testdata/fixedbugs/issue51437.go

@@ -0,0 +1,17 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type T struct{}
+
+func (T) m() []int { return nil }
+
+func f(x T) {
+	for _, x := range func() []int {
+		return x.m() // x declared in parameter list of f
+	}() {
+		_ = x // x declared by range clause
+	}
+}

src/cmd/compile/internal/types2/testdata/fixedbugs/issue51472.go2

@@ -0,0 +1,54 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+func _[T comparable](x T) {
+        _ = x == x
+}
+
+func _[T interface{interface{comparable}}](x T) {
+        _ = x == x
+}
+
+func _[T interface{comparable; interface{comparable}}](x T) {
+        _ = x == x
+}
+
+func _[T interface{comparable; ~int}](x T) {
+        _ = x == x
+}
+
+func _[T interface{comparable; ~[]byte}](x T) {
+        _ = x /* ERROR cannot compare */ == x
+}
+
+// TODO(gri) The error message here should be better. See issue #51525.
+func _[T interface{comparable; ~int; ~string}](x T) {
+        _ = x /* ERROR cannot compare */ == x
+}
+
+// TODO(gri) The error message here should be better. See issue #51525.
+func _[T interface{~int; ~string}](x T) {
+        _ = x /* ERROR cannot compare */ == x
+}
+
+func _[T interface{comparable; interface{~int}; interface{int|float64}}](x T) {
+        _ = x == x
+}
+
+func _[T interface{interface{comparable; ~int}; interface{~float64; comparable; m()}}](x T) {
+        _ = x /* ERROR cannot compare */ == x
+}
+
+// test case from issue
+
+func f[T interface{comparable; []byte|string}](x T) {
+        _ = x == x
+}
+
+func _(s []byte) {
+	f( /* ERROR \[\]byte does not implement interface{comparable; \[\]byte\|string} */ s)
+        _ = f[[ /* ERROR does not implement */ ]byte]
+}

src/cmd/compile/internal/types2/testdata/fixedbugs/issue51509.go

@@ -0,0 +1,7 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type T /* ERROR illegal cycle */ T.x

src/cmd/compile/internal/types2/testdata/fixedbugs/issue51578.go2

@@ -0,0 +1,17 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+var _ = (*interface /* ERROR interface contains type constraints */ {int})(nil)
+
+// abbreviated test case from issue
+
+type TypeSet interface{ int | string }
+
+func _() {
+	f((*TypeSet /* ERROR interface contains type constraints */)(nil))
+}
+
+func f(any) {}

src/cmd/compile/internal/types2/testdata/fixedbugs/issue51593.go2

@@ -0,0 +1,13 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+func f[P interface{ m(R) }, R any]() {}
+
+type T = interface { m(int) }
+
+func _() {
+	_ = f[ /* ERROR cannot infer R */ T] // don't crash in type inference
+}

src/cmd/compile/internal/types2/type.go

@@ -7,9 +7,7 @@ package types2
 // A Type represents a type of Go.
 // All types implement the Type interface.
 type Type interface {
-	// Underlying returns the underlying type of a type
+	// Underlying returns the underlying type of a type.
-	// w/o following forwarding chains. Only used by
-	// client packages.
 	Underlying() Type
 
 	// String returns a string representation of a type.
@@ -27,13 +25,13 @@ func under(t Type) Type {
 	return t.Underlying()
 }
 
-// If t is not a type parameter, structuralType returns the underlying type.
+// If t is not a type parameter, coreType returns the underlying type.
-// If t is a type parameter, structuralType returns the single underlying
+// If t is a type parameter, coreType returns the single underlying
 // type of all types in its type set if it exists, or nil otherwise. If the
 // type set contains only unrestricted and restricted channel types (with
 // identical element types), the single underlying type is the restricted
 // channel type if the restrictions are always the same, or nil otherwise.
-func structuralType(t Type) Type {
+func coreType(t Type) Type {
 	tpar, _ := t.(*TypeParam)
 	if tpar == nil {
 		return under(t)
@@ -59,10 +57,10 @@ func structuralType(t Type) Type {
 	return nil
 }
 
-// structuralString is like structuralType but also considers []byte
+// coreString is like coreType but also considers []byte
 // and strings as identical. In this case, if successful and we saw
 // a string, the result is of type (possibly untyped) string.
-func structuralString(t Type) Type {
+func coreString(t Type) Type {
 	tpar, _ := t.(*TypeParam)
 	if tpar == nil {
 		return under(t) // string or untyped string

src/cmd/compile/internal/types2/typeparam.go

@@ -31,11 +31,13 @@ func (t *TypeParam) Obj() *TypeName { return t.obj }
 // or Signature type by calling SetTypeParams. Setting a type parameter on more
 // than one type will result in a panic.
 //
-// The constraint argument can be nil, and set later via SetConstraint.
+// The constraint argument can be nil, and set later via SetConstraint. If the
+// constraint is non-nil, it must be fully defined.
 func NewTypeParam(obj *TypeName, constraint Type) *TypeParam {
 	return (*Checker)(nil).newTypeParam(obj, constraint)
 }
 
+// check may be nil
 func (check *Checker) newTypeParam(obj *TypeName, constraint Type) *TypeParam {
 	// Always increment lastID, even if it is not used.
 	id := nextID()
@@ -50,9 +52,7 @@ func (check *Checker) newTypeParam(obj *TypeName, constraint Type) *TypeParam {
 	// iface may mutate typ.bound, so we must ensure that iface() is called
 	// at least once before the resulting TypeParam escapes.
 	if check != nil {
-		check.later(func() {
+		check.needsCleanup(typ)
-			typ.iface()
-		})
 	} else if constraint != nil {
 		typ.iface()
 	}
@@ -72,8 +72,10 @@ func (t *TypeParam) Constraint() Type {
 
 // SetConstraint sets the type constraint for t.
 //
-// SetConstraint should not be called concurrently, but once SetConstraint
+// It must be called by users of NewTypeParam after the bound's underlying is
-// returns the receiver t is safe for concurrent use.
+// fully defined, and before using the type parameter in any way other than to
+// form other types. Once SetConstraint returns the receiver, t is safe for
+// concurrent use.
 func (t *TypeParam) SetConstraint(bound Type) {
 	if bound == nil {
 		panic("nil constraint")
@@ -93,9 +95,12 @@ func (t *TypeParam) String() string { return TypeString(t, nil) }
 // ----------------------------------------------------------------------------
 // Implementation
 
+func (t *TypeParam) cleanup() {
+	t.iface()
+	t.check = nil
+}
+
 // iface returns the constraint interface of t.
-// TODO(gri) If we make tparamIsIface the default, this should be renamed to under
-//           (similar to Named.under).
 func (t *TypeParam) iface() *Interface {
 	bound := t.bound
 
@@ -136,16 +141,6 @@ func (t *TypeParam) iface() *Interface {
 	return ityp
 }
 
-// singleType returns the single type of the type parameter constraint; or nil.
-func (t *TypeParam) singleType() Type {
-	return t.iface().typeSet().singleType()
-}
-
-// hasTerms reports whether the type parameter constraint has specific type terms.
-func (t *TypeParam) hasTerms() bool {
-	return t.iface().typeSet().hasTerms()
-}
-
 // is calls f with the specific type terms of t's constraint and reports whether
 // all calls to f returned true. If there are no specific terms, is
 // returns the result of f(nil).