An index expression followed by an opening "{" may indicate
a composite literal but only if the index expression can be
a type. Exclude cases where the index expression cannot be
a type (e.g. s[0], a[i+j], etc.).
This leads to a better error message in code that is erroneous.
Fixes#46558.
Change-Id: Ida9291ca30683c211812dfb95abe4969f44c474f
Reviewed-on: https://go-review.googlesource.com/c/go/+/325009
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
The parser accepted embedded elements but the first term
of an element had to be a ~-term or a type name. This CL
fixes that.
Change-Id: I013b6cdc5963fb228867ca6597f9139db2be7ec5
Reviewed-on: https://go-review.googlesource.com/c/go/+/321109
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
This is a modified port of the https://golang.org/cl/313909
change for go/types.
- add catch-all cases for unexpected expression lists
- add Checker.singleIndex function to check single indices
- better syntax error handling in parser for invalid type
instantiations that are missing a type argument
Change-Id: I6f0f396d637ad66b79f803d886fdc20ee55a98b3
Reviewed-on: https://go-review.googlesource.com/c/go/+/314409
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
Only complain about missing type; leave it to type-checking
to decide whether "..." is permitted in the first place.
Fixes#43674.
Change-Id: Icbc8f084e364fe3ac16076406a134354219c08d0
Reviewed-on: https://go-review.googlesource.com/c/go/+/310209
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
Type lists continue to be accepted as before.
While at it, print missing filenames in error tests
(which uses an ad-hoc position representation).
Change-Id: I933b3acbc9cf1985ad8f70f6b206e3a1dbd64d1e
Reviewed-on: https://go-review.googlesource.com/c/go/+/307371
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
Represent x++/-- as x +=/-= with the RHS of the assignment being nil
rather than syntax.ImplicitOne.
Dependent code already had to check for syntax.ImplicitOne, but
then shared some existing code for regular assignment operations.
Now always handle this case fully explicit, which simplifies the
code.
Change-Id: I28c7918153c27cbbf97b041d0c85ff027c58687c
Reviewed-on: https://go-review.googlesource.com/c/go/+/285172
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Report an error otherwise.
Change-Id: Ia76ea03a3f26b13dd9bca49f7bd42101d1ff1f9e
Reviewed-on: https://go-review.googlesource.com/c/go/+/278475
Trust: Robert Griesemer <gri@golang.org>
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
In package syntax:
- fix parser appendGroup to not add nil entries
- non-string paths are syntax errors per the spec; report in parser
- document ImportDecl.Path invariants
In package types2:
- guard against absent paths
In package gc:
- guard against absent paths
Fixes#43190.
Change-Id: Ic6a06f6a96b7f519feaa1ceaf4376fc5ab0f0129
Reviewed-on: https://go-review.googlesource.com/c/go/+/278114
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
Most syntax.Nodes are allocated in one place and there didn't
seem a need to provide factory methods - so as a matter of
API design, all nodes are "naked", without any constructors.
However, Name nodes are frequently used/replaced and also
are created as helper nodes in clients (types2). Make an
exception and export NewName.
Change-Id: I4b5c499d65bba74592dea68b0936c118b3edaca7
Reviewed-on: https://go-review.googlesource.com/c/go/+/277572
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
Per @mdempsky's suggestion: Instead of representing a type instantiation T[P]
by an IndexExpr node, and a type instantiation with multiple type arguments
T[P1, P2] by a CallExpr node with special Brackets flag, always use an IndexExpr.
Use a ListExpr as index in the (less common) case of multiple type arguments.
This removes the need for the CallExpr.Brackets field and cleans up the parser
code around type instantiations.
Backport of syntax package changes from https://golang.org/cl/262020.
Change-Id: I32e8bc4eafac5b3ef2e7eb40fa8c790a5a905b69
Reviewed-on: https://go-review.googlesource.com/c/go/+/262137
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Port from dev.go2go prototype branch. The compiler doesn't yet set the
syntax.AllowGenerics mode, so parsing of generic code remains disabled.
Known issue: The doc strings documenting the specific syntax accepted
by parser methods are not all up-to-date.
Change-Id: I13d134289fd9330fd0ed7f97c997cca6f23466fd
Reviewed-on: https://go-review.googlesource.com/c/go/+/261658
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
- add TParamList fields to TypeDecl, FuncDecl
- also: change File.Lines to File.EOF so we have the actual file end position
Change-Id: Ia345f888080a884f7ac5cefd8bff3d80e4a59cdc
Reviewed-on: https://go-review.googlesource.com/c/go/+/261657
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
- For "if" statements without a condition, provide a BadExpr rather than nil
(clients expect IfStmt.Cond != nil since the parser is taking care of
reporting a missing condition).
- For 3-index slice expressions, also provide BadExpr where an index is
required but missing.
- Declare a parser-local error method to hide the embedded error method
so we don't use it by mistake.
Accidentally found while adjusting prototype parser to work for generics.
Change-Id: Iacc211cc60869be05efe9ae630d65dff1dac00a0
Reviewed-on: https://go-review.googlesource.com/c/go/+/261218
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Thie CL changes cmd/compile/internal/syntax to give the gc half of
the compiler more control over pragma handling, so that it can prepare
better errors, diagnose misuse, and so on. Before, the API between
the two was hard-coded as a uint16. Now it is an interface{}.
This should set us up better for future directives.
In addition to the split, this CL emits a "misplaced compiler directive"
error for any directive that is in a place where it has no effect.
I've certainly been confused in the past by adding comments
that were doing nothing and not realizing it. This should help
avoid that kind of confusion.
The rule, now applied consistently, is that a //go: directive
must appear on a line by itself immediately before the declaration
specifier it means to apply to. See cmd/compile/doc.go for
precise text and test/directive.go for examples.
This may cause some code to stop compiling, but that code
was broken. For example, this code formerly applied the
//go:noinline to f (not c) but now will fail to compile:
//go:noinline
const c = 1
func f() {}
Change-Id: Ieba9b8d90a27cfab25de79d2790a895cefe5296f
Reviewed-on: https://go-review.googlesource.com/c/go/+/228578
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
This is one of several changes that were part of a larger rewrite
which I made in early 2019 after switching to the new number literal
syntax implementation. The purpose of the rewrite was to simplify
reading of source code (Unicode character by character) and speed up
the scanner but was never submitted for review due to other priorities.
Part 3 of 3:
This change contains a complete rewrite of source.go, the file that
implements reading individual Unicode characters from the source.
The new implementation is easier to use and has simpler literal
buffer management, resulting in faster scanner and thus parser
performance.
Thew new source.go (internal) API is centered around nextch() which
advances the scanner by one character. The scanner has been adjusted
around nextch() and now consistently does one character look-ahead
(there's no need for complicated ungetr-ing anymore). Only in one
case backtrack is needed (when finding '..' rather than '...') and
that case is now more cleanly solved with the new reset() function.
Measuring line/s parsing peformance by running
go test -run StdLib -fast -skip "syntax/(scanner|source)\.go"
(best of 5 runs on "quiet" MacBook Pro, 3.3GHz Dual-Core i7, 16GB RAM,
OS X 10.15.3) before and after shows consistently 3-5% improvement of
line parsing speed:
old: parsed 1788155 lines (3969 files) in 1.255520307s (1424234 lines/s)
new: parsed 1788155 lines (3969 files) in 1.213197037s (1473919 lines/s)
(scanner.go and parser.go are skipped because this CL changed those files.)
Change-Id: Ida947f4b538d42eb2d2349062c69edb6c9e5ca66
Reviewed-on: https://go-review.googlesource.com/c/go/+/221603
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
The error message is now positioned at the statement position (which is
an identifing token, such as the '=' for assignments); and in case of
assignments it emphasizes the assignment by putting the Lhs and Rhs
in parentheses. Finally, the wording is changed from "use of * as value"
to the stronger "cannot use * as value" (for which there is precedent
elsewhere in the parser).
Fixes#36858.
Change-Id: Ic3f101bba50f58e3a1d9b29645066634631f2d61
Reviewed-on: https://go-review.googlesource.com/c/go/+/218337
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
The new (internal) field scanner.bad indicates whether a syntax error
occurred while scanning a literal; the corresponding scanner.lit
string may be syntactically incorrect in that case. Store the value
of scanner.bad together with the scanner.lit in BasicLit.
Clean up error handling so that all syntactic errors use one of the
scanner's error reporting methods which also set scanner.bad. Make
use of the new field in a few places where we used to track a prior
error separately.
Preliminary step towards fixing #32133 in a comprehensive manner.
Change-Id: I4d79ad6e3b50632dd5fb3fc32ca3df0598ee77b4
Reviewed-on: https://go-review.googlesource.com/c/go/+/192278
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Don't skip closing parentheses of any kind after a missing
expression. They are likely part of the lexical construct
enclosing the expression.
Fixes#33386.
Change-Id: Ic0abc2037ec339a345ec357ccc724b7ad2a64c00
Reviewed-on: https://go-review.googlesource.com/c/go/+/188502
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Before this fix, a mistaken := in a (const/type/var) declaration
ended that declaration with an error from which the parser didn't
recover well. This low-cost change will provide a better error
message and lets the parser recover perfectly.
Fixes#31092.
Change-Id: Ic4f94dc5e29dd00b7ef6d53a80dded638e3cea80
Reviewed-on: https://go-review.googlesource.com/c/go/+/169958
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Don't report errors if we don't have a correct type switch
guard; instead ignore it and leave it to the type-checker
to report the error. This leads to better error messages
concentrating on the type switch guard rather than errors
around (confusing) syntactic details.
Also clean up some code setting up AssertExpr (they never
have a nil Type field) and remove some incorrect TODOs.
Fixes#24470.
Change-Id: I69512f36e0417e3b5ea9c8856768e04b19d654a8
Reviewed-on: https://go-review.googlesource.com/103615
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This change enables printing of relative column information if a
prior line directive specified a valid column. If there was no
line directive, or the line directive didn't specify a column
(or the -C flag is specified), no column information is shown in
file positions.
Implementation: Column values (and line values, for that matter)
that are zero are interpreted as "unknown". A line directive that
doesn't specify a column records that as a zero column in the
respective PosBase data structure. When computing relative columns,
a relative value is zero of the base's column value is zero.
When formatting a position, a zero column value is not printed.
To make this work without special cases, the PosBase for a file
is given a concrete (non-0:0) position 1:1 with the PosBase's
line and column also being 1:1. In other words, at the position
1:1 of a file, it's relative positions are starting with 1:1 as
one would expect.
In the package syntax, this requires self-recursive PosBases for
file bases, matching what cmd/internal/src.PosBase was already
doing. In src.PosBase, file and inlining bases also need to be
based at 1:1 to indicate "known" positions.
This change completes the cmd/compiler part of the issue below.
Fixes#22662.
Change-Id: I6c3d2dee26709581fba0d0261b1d12e93f1cba1a
Reviewed-on: https://go-review.googlesource.com/97375
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
For line directives which have a line and a column number,
an omitted filename means that the filename has not changed
(per the issue below).
For line directives w/o a column number, an omitted filename
means the empty filename (to preserve the existing behavior).
For #22662.
Change-Id: I32cd9037550485da5445a34bb104706eccce1df1
Reviewed-on: https://go-review.googlesource.com/96476
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
The existing code was somewhat convoluted and made several assumptions
about the encoding of position bases:
1) The position's base for a file contained a position whose base
pointed to itself (which is true but an implementation detail
of src.Pos).
2) Updating the position base for a line directive required finding
the base of the most recent's base position.
This change simply stores the file's position base and keeps using it
directly for each line directive (instead of getting it from the most
recently updated base).
Change-Id: I4d80da513bededb636eab0ce53257fda73f0dbc0
Reviewed-on: https://go-review.googlesource.com/95736
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Assume that an expression that is not a function call in a defer/go
statement is indeed a function that is just missing its invocation.
Report the error but continue with a sane syntax tree.
Fixes#23586.
Change-Id: Ib45ebac57c83b3e39ae4a1b137ffa291dec5b50d
Reviewed-on: https://go-review.googlesource.com/94156
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Also, remove parser.error method (in favor of parser.errorAt) as it's only
used twice.
This is a purely cosmetic change.
Change-Id: Idb3b8b50f1c2e4d10de2ffb1c1184ceba8f7de8a
Reviewed-on: https://go-review.googlesource.com/94030
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
R=go1.11
In order to collect comments in the AST and for error testing purposes,
the scanner needs to not only recognize and skip comments, but also be
able to report them if so desired. This change adds a mode flag to the
scanner's init function which controls the scanner behavior around
comments.
In the common case where comments are not needed, there must be no
significant overhead. Thus, comments are reported via a handler upcall
rather than being returned as a _Comment token (which the parser would
have to filter out with every scanner.next() call).
Because the handlers for error messages, directives, and comments all
look the same (they take a position and text), and because directives
look like comments, and errors never start with a '/', this change
simplifies the scanner's init call to only take one (error) handler
instead of 2 or 3 different handlers with identical signature. It is
trivial in the handler to determine if we have an error, directive,
or general comment.
Finally, because directives are comments, when reporting directives
the full comment text is returned now rather than just the directive
text. This simplifies the implementation and makes the scanner API
more regular. Furthermore, it provides important information about
the comment style used by a directive, which may matter eventually
when we fully implement /*line file:line:col*/ directives.
Change-Id: I2adbfcebecd615e4237ed3a832b6ceb9518bf09c
Reviewed-on: https://go-review.googlesource.com/88215
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
R=go1.11
A common error is to write '=' instead of '==' inside the condition
of a simple 'if' statement:
if x = 0 { ... }
Highlight the fact that we have an assignment in the error message
to prevent further confusion.
Fixes#23385.
Change-Id: I1552050fd6da927bd12a1be0977bd2e98eca5885
Reviewed-on: https://go-review.googlesource.com/87316
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
R=go1.11
This implements parsing of /*line file:line*/ and /*line file:line:col*/
directives and also extends the optional column format to regular //line
directives, per #22662.
For a line directive to be recognized, its comment text must start with
the prefix "line " which is followed by one of the following:
:line
:line:col
filename:line
filename:line:col
with at least one : present. The line and col values must be unsigned
decimal integers; everything before is considered part of the filename.
Valid line directives are:
//line :123
//line :123:8
//line foo.go:123
//line C:foo.go:123 (filename is "C:foo.go")
//line C:foo.go:123:8 (filename is "C:foo.go")
/*line ::123*/ (filename is ":")
No matter the comment format, at the moment all directives act as if
they were in //line comments, and column information is ignored.
To be addressed in subsequent CLs.
For #22662.
Change-Id: I1a2dc54bacc94bc6cdedc5229ee13278971f314e
Reviewed-on: https://go-review.googlesource.com/86037
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Also, with this change, error locations don't print absolute positions
in [] brackets following positions relative to line directives. To get
the absolute positions as well, specify the -L flag.
Fixes#22660.
Change-Id: I9ecfa254f053defba9c802222874155fa12fee2c
Reviewed-on: https://go-review.googlesource.com/77090
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Be more pessimistic when parsing if/switch/for headers for better error
messages when things go wrong.
Fixes#22581.
Change-Id: Ibb99925291ff53f35021bc0a59a4c9a7f695a194
Reviewed-on: https://go-review.googlesource.com/76290
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
When an opening "{" of a block is missing and after advancing we
find a closing "}", it's likely better to assume the end of the
block. Fixed and removed TODO.
Change-Id: I20c9b4ecca798933a7cd4cbf21185bd4ca04f5f7
Reviewed-on: https://go-review.googlesource.com/71291
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
- checking for the correct closing token leads to slightly better
behavior for some randomly bogus programs
- removed `switch` in favor of an `if` statement
Follow-up on https://go-review.googlesource.com/c/go/+/71250.
Change-Id: I47f6c47b43baf790907f55ed97a947661687a9db
Reviewed-on: https://go-review.googlesource.com/71252
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Fine-tune skipping of tokens after missing closing parentheses in lists.
Fixes#22164.
Change-Id: I575d86e21048cd40340a2c08399e8b0deec337cf
Reviewed-on: https://go-review.googlesource.com/71250
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Instead of repeating the same list parsing pattern for parenthesized
of braced comma or semicolon-separated lists, introduce a single list
parsing function that can be parametrized and which takes a closure
to parse list elements.
This ensures the same error handling and recovery logic is used across
all lists and simplifies the code.
No semantic change.
Change-Id: Ia738d354d6c2e0c3d84a5f1c7269a6eb95685edc
Reviewed-on: https://go-review.googlesource.com/70492
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
No semantic change. Move functionality not related to argument
out of the argument parsing function, and thus match parameter
parsing. Also, use a better function name.
Change-Id: Ic550875251d64e6fe1ebf91c11d33a9e4aec9fdd
Reviewed-on: https://go-review.googlesource.com/70491
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This re-enables functionality that inadvertently was disabled in the
(long) past.
Also, don't perform branch checks if we had errors in a function
to avoid spurious errors or (worst-case) crashes.
Slightly modified test/fixedbugs/issue14006.go to make sure the
test still reports invalid label errors (the surrounding function
must be syntactically correct).
Change-Id: Id5642930877d7cf3400649094ec75c753b5084b7
Reviewed-on: https://go-review.googlesource.com/69770
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
The compiler replaces any path of the form /path/to/goroot/src/net/port.go
with GOROOT/src/net/port.go so that the same object file is
produced if the GOROOT is moved. It was skipping this transformation
for any absolute path into the GOROOT that came from //line directives,
such as those generated by cmd/cgo.
Fixes#21373Fixes#21720Fixes#21825
Change-Id: I2784c701b4391cfb92e23efbcb091a84957d61dd
Reviewed-on: https://go-review.googlesource.com/63693
Run-TryBot: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Fixes crash when printing a related error message later on.
Fixes#20789.
Change-Id: I6d2c35aafcaeda26a211fc6c8b7dfe4a095a3efe
Reviewed-on: https://go-review.googlesource.com/46713
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Instead of a separate check control flow pass (checkcfg.go)
operating on nodes, perform this check at parse time on the
new syntax tree. Permits this check to be done concurrently,
and doesn't depend on the specifics of the symbol's dclstack
implementation anymore. The remaining dclstack uses will be
removed in a follow-up change.
- added CheckBranches Mode flag (so we can turn off the check
if we only care about syntactic correctness, e.g. for tests)
- adjusted test/goto.go error messages: the new branches
checker only reports if a goto jumps into a block, but not
which block (we may want to improve this again, eventually)
- also, the new branches checker reports one variable that
is being jumped over by a goto, but it may not be the first
one declared (this is fine either way)
- the new branches checker reports additional errors for
fixedbugs/issue14006.go (not crucial to avoid those errors)
- the new branches checker now correctly reports only
variable declarations being jumped over, rather than
all declarations (issue 8042). Added respective tests.
Fixes#8042.
Change-Id: I53b6e1bda189748e1e1fb5b765a8a64337c27d40
Reviewed-on: https://go-review.googlesource.com/39998
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Now that we have consistent use of xOrNil parse methods, we don't
need a special missing_statement singleton to distinguish between
missing actually statements and other errors (which have returned
nil before).
For #19663.
Change-Id: I8364f1441bdf8dd966bcd6d8219b2a42d6b88abd
Reviewed-on: https://go-review.googlesource.com/38656
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
- parser creates sensible nodes in case of syntax errors instead of nil
- a new BadExpr node is used in places where we can't do better
- fixed error message for incorrect type switch guard
- minor cleanups
Fixes#19663.
Change-Id: I028394c6db9cba7371f0e417ebf93f594659786a
Reviewed-on: https://go-review.googlesource.com/38653
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
