For golang/go#60028.

Change-Id: I4c7a726a900fc7c4b34816eba5cfd0361c45315f
Reviewed-on: https://go-review.googlesource.com/c/mod/+/492990
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>

As part of the forward compatibility work, a new toolchain line
is being added, and go lines are allowed to specify toolchain
versions like "1.21.0" or "1.21rc1" now. (The lax RE has allowed this for quite
some time; what's new here is allowing it in the main module.)

For golang/go#57001.

Change-Id: I1dc01289381fe080644a7a391b97a65158938f39
Reviewed-on: https://go-review.googlesource.com/c/mod/+/497397
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Russ Cox <rsc@golang.org>

Add new toolchain directive to go.mod and go.work parser.
Also fix error checking in parsing tests.

For golang/go#57001.

Change-Id: Ib7603f82cbd667f2152ed6b0c5989f08c28ceb1c
Reviewed-on: https://go-review.googlesource.com/c/mod/+/497399
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>

Also add tests of previous CLs.

For golang/go#57001.

Change-Id: I755429dd07c0e84910108ce9807d607115329b79
Reviewed-on: https://go-review.googlesource.com/c/mod/+/497400
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>

Change-Id: Ic0a9149713f7981e44629b2d96cf2a6ec52d6976
Reviewed-on: https://go-review.googlesource.com/c/mod/+/500455
Reviewed-by: Bryan Mills <bcmills@google.com>
Auto-Submit: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Bryan Mills <bcmills@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

Change-Id: Idb3276b201dbce094201fc5824a1e151f4f71ce8
Reviewed-on: https://go-review.googlesource.com/c/mod/+/500456
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>

Final revisions for Go 1.21: lock down the toolchain syntax to use
'toolchain default' instead of 'toolchain local', to avoid confusion
with 'GOTOOLCHAIN=local'; 'toolchain local' does not always mean
the same thing.

Also remove the prefix-go1.2.3 toolchain name form, leaving only
go1.2.3-suffix. There is no need to have two different forms, and it's
confusing.

For golang/go#57001.

Change-Id: I16623c796c620e98178deed899e28a00e85fcc21
Reviewed-on: https://go-review.googlesource.com/c/mod/+/500755
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>

The go command tests use a network stack that sometimes
panics during read. This code was assuming a network stack
that returns errors instead. If a tile-reading goroutine panicked,
ReadTiles considered it done with data, err = nil, nil, and then
there was a race between ReadTiles failing with an error about
a suspiciously short tile and the panicking goroutine getting
to run and bring down the entire program.

Remove the race by converting the panic into an error during
ReadTiles.

For a test in golang/go#57001.

Change-Id: I9b18a244238e67c27a15b93f8397bf3ab44b06e6
Reviewed-on: https://go-review.googlesource.com/c/mod/+/501035
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>