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5b42f89e39
Extend the context package to allow users to specify why a context was canceled in the form of an error, the "cause". Users write the cause by calling WithCancelCause to construct a derived context, then calling cancel(cause) to cancel the context with the provided cause. Users retrieve the cause by calling context.Cause(ctx), which returns the cause of the first cancelation for ctx or any of its parents. The cause is implemented as a field of cancelCtx, since only cancelCtx can be canceled. Calling cancel copies the cause to all derived (child) cancelCtxs. Calling Cause(ctx) finds the nearest parent cancelCtx by looking up the context value keyed by cancelCtxKey. API changes: +pkg context, func Cause(Context) error +pkg context, func WithCancelCause(Context) (Context, CancelCauseFunc) +pkg context, type CancelCauseFunc func(error) Fixes #26356 Fixes #51365 Change-Id: I15b62bd454c014db3f4f1498b35204451509e641 Reviewed-on: https://go-review.googlesource.com/c/go/+/375977 Reviewed-by: Damien Neil <dneil@google.com> TryBot-Result: Gopher Robot <gobot@golang.org> Run-TryBot: Sameer Ajmani <sameer@golang.org> Auto-Submit: Sameer Ajmani <sameer@golang.org>
Files in this directory are data for Go's API checker ("go tool api", in src/cmd/api).
Each file is a list of API features, one per line.
go1.txt (and similarly named files) are frozen once a version has been
shipped. Each file adds new lines but does not remove any.
except.txt lists features that may disappear without breaking true
compatibility.
Starting with go1.19.txt, each API feature line must end in "#nnnnn"
giving the GitHub issue number of the proposal issue that accepted
the new API. This helps with our end-of-cycle audit of new APIs.
The same requirement applies to next/* (described below), which will
become a go1.XX.txt for XX >= 19.
The next/ directory contains the only files intended to be mutated.
Each file in that directory contains a list of features that may be added
to the next release of Go. The files in this directory only affect the
warning output from the go api tool. Each file should be named
nnnnn.txt, after the issue number for the accepted proposal.
(The #nnnnn suffix must also appear at the end of each line in the file;
that will be preserved when next/*.txt is concatenated into go1.XX.txt.)