cmd/compile: internal compiler error with 2 _ labels

[leabit]

Go version

Go 1.23

Output of go env in your module/workspace:

/

What did you do?

Playground: https://go.dev/play/p/Qjo8Uh4a4eL

package main

func f() {
_:

_:
}

func main() {
	f()
}

What did you see happen?

./prog.go:10:3: internal compiler error: label ~_·1 missing tag

Please file a bug report including a short program that triggers the error.
https://go.dev/issue/new

What did you expect to see?

To work without errors.

[gabyhelp]

Related Issues and Documentation

• cmd/compile: crash on an unusual program #52278 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[leabit]

Similar, but not the same as the #52278. It now works as expected in that case, but not in the one I provided.

[zigo101]

Since v1.18.

[cuonglm]

Similar, but not the same as the #52278. It now works as expected in that case, but not in the one I provided.

The reason is that _ was mangled during inlining, causing the check for blank node failed.

CL 624377 will fix this.

[gopherbot]

Change https://go.dev/cl/624377 mentions this issue: cmd/compile: fix inlining name mangling for blank label