cmd/compile: fails to bootstrap with go1.21.9 at 15cec430d7

[pmur]

Go version

master

Output of go env in your module/workspace:

GOARCH=ppc64le and GOARCH=amd64
GOOS=linux

What did you do?

# checkout upstream go commit 076166ab4e
GOROOT_BOOTSTRAP=~/path/to/go1.21.9 ./make.bash

What did you see happen?

Building Go cmd/dist using /home/murp/go-bootstrap-121. (go1.21.9 linux/ppc64le)
Building Go toolchain1 using /home/murp/go-bootstrap-121.
Building Go bootstrap cmd/go (go_bootstrap) using Go toolchain1.
<unknown line number>: internal compiler error: panic: godebug: Value of name not listed in godebugs.All: gotypesalias

goroutine 1 [running]:
runtime/debug.Stack()
	/home/murp/go-bootstrap-121/src/runtime/debug/stack.go:24 +0x6c
bootstrap/cmd/compile/internal/base.FatalfAt({0x2152c?, 0x0?}, {0x79e1fb, 0x9}, {0xc000186c80, 0x1, 0x1})
	/home/murp/git/go/src/cmd/compile/internal/base/print.go:225 +0x270
bootstrap/cmd/compile/internal/base.Fatalf(...)
	/home/murp/git/go/src/cmd/compile/internal/base/print.go:194
bootstrap/cmd/compile/internal/gc.handlePanic()
	/home/murp/git/go/src/cmd/compile/internal/gc/main.go:52 +0xa4
panic({0x6f3260?, 0xc00003ca00?})
	/home/murp/go-bootstrap-121/src/runtime/panic.go:914 +0x27c
internal/godebug.(*Setting).Value.func1()
	/home/murp/go-bootstrap-121/src/internal/godebug/godebug.go:141 +0xf4
sync.(*Once).doSlow(0xc0000de401?, 0x5c4864?)
	/home/murp/go-bootstrap-121/src/sync/once.go:74 +0x110
sync.(*Once).Do(...)
	/home/murp/go-bootstrap-121/src/sync/once.go:65
internal/godebug.(*Setting).Value(0xcb9180)
	/home/murp/go-bootstrap-121/src/internal/godebug/godebug.go:138 +0x78
bootstrap/cmd/compile/internal/types2.NewChecker(0x7fffffffe898?, 0xc000466120, 0x0?)
	/home/murp/git/go/src/cmd/compile/internal/types2/check.go:261 +0x8c
bootstrap/cmd/compile/internal/types2.(*Config).Check(0x79be6d?, {0x7fffffffe898?, 0x7a6074?}, {0xc00009c598, 0x1, 0x1}, 0x1d8d88?)
	/home/murp/git/go/src/cmd/compile/internal/types2/api.go:470 +0x98
bootstrap/cmd/compile/internal/noder.checkFiles({0x0, {0x0, 0x0}}, {0xc00009c528, 0x1, 0x18?})
	/home/murp/git/go/src/cmd/compile/internal/noder/irgen.go:93 +0x5a0
bootstrap/cmd/compile/internal/noder.writePkgStub({0x0?, {0x0?, 0x0?}}, {0xc00009c528, 0x1, 0x1})
	/home/murp/git/go/src/cmd/compile/internal/noder/unified.go:304 +0x7c
bootstrap/cmd/compile/internal/noder.unified({0x0?, {0x0?, 0x0?}}, {0xc00009c528?, 0x6e2500?, 0x0?})
	/home/murp/git/go/src/cmd/compile/internal/noder/unified.go:180 +0xf4
bootstrap/cmd/compile/internal/noder.LoadPackage({0xc00001e1d0, 0x1, 0x1})
	/home/murp/git/go/src/cmd/compile/internal/noder/noder.go:77 +0x468
bootstrap/cmd/compile/internal/gc.Main(0x7d72b0)
	/home/murp/git/go/src/cmd/compile/internal/gc/main.go:197 +0xce0
main.main()
	/home/murp/git/go/src/cmd/compile/main.go:57 +0x134

What did you expect to see?

A few lines indicating the toolchain bootstrapped.

[pmur]

@griesemer FYI, this is causing CI failures for ppc64x and a few others which bootstrap with 1.21.9.

[cherrymui]

With the revert CL https://go.dev/cl/579575 submitted, is it still failing? Thanks.

[pmur]

Yes, the CI is still continuing to fail bootstrap. It failed on amd64 and ppc64le at 076166ab4e when I tried it.

[cherrymui]

Okay, thanks.

[ianlancetaylor]

CC @griesemer @alandonovan @findleyr Same as #66873 ?

[griesemer]

I don't think it's the same as #66873: that one is related to enabled type alias nodes, while this is about bootstrapping. This looks similar to the problem encountered here: https://go.dev/cl/579575 .

This failure seems to be related to the way gotypesalias is declared in the code (in cmd/compile/internal/types2/check.go:27):

godebug.New("gotypesalias")

vs

godebug.New("#gotypesalias") // note the #

It's not clear why the # is needed because the flag is in the table (contrary to the error message reported). There may be a bug in the handling of # for GODEBUG settings.

[griesemer]

I note that https://go.dev/cl/579076/ removed the # from the godebug.New("#gotypesalias") because the most up-to-date flag setting is not seen when bootstrapping with 1.20 and the # is present (the respective godebug changes happened in https://go.dev/cl/476280). I suspect there's an issue here with the handling of #.

[cherrymui]

The internal/godebug package is not listed as a bootstrap package (not in this list https://cs.opensource.google/go/go/+/master:src/cmd/dist/buildtool.go;l=33), so at bootstrapping, it uses the bootstrap toolchain's (Go 1.21.9) internal/godebug package, instead of the one in GOROOT. This is also seen in the stack trace above

internal/godebug.(*Setting).Value(0xcb9180)
	/home/murp/go-bootstrap-121/src/internal/godebug/godebug.go:138 +0x78
bootstrap/cmd/compile/internal/types2.NewChecker(0x7fffffffe898?, 0xc000466120, 0x0?)
	/home/murp/git/go/src/cmd/compile/internal/types2/check.go:261 +0x8c

It is internal/godebug, not bootstrap/internal/godebug.

We can't simply add internal/godebug to the list, as internal/godebug uses runtime functions that doesn't exist in the bootstrap runtime... Maybe there is a way around? I'm not sure. Perhaps we can make it godebug.New("#gotypesalias") (with #) just for bootstrapping (with compiler_bootstrap build tag), then build regular compiler without #.

[gopherbot]

Change https://go.dev/cl/579835 mentions this issue: cmd/compile: use #gotypesalias for bootstrap

[gopherbot]

Change https://go.dev/cl/579875 mentions this issue: types2: don't access gotypesalias during bootstrap (before 1.22)

[gopherbot]

Change https://go.dev/cl/579935 mentions this issue: go/types, types2: use types2.Config flag to control Alias node creation