cmd/compile: failures with "symbol type.[…] listed multiple times" on freebsd-amd64-12_2 since 2021-11-24

[bcmills]

greplogs --dashboard -md -l -e 'symbol type.* listed multiple times'

2021-12-02T15:48:58-28ec0fd/freebsd-amd64-12_2
2021-12-01T18:47:44-3c63f30-08ecdf7/freebsd-amd64-12_2
2021-11-24T05:36:54-7cf1f38-47db3bb/freebsd-amd64-12_2

[bcmills]

Marking as release-blocker for Go 1.18 because this failure mode appears to be new as of November.
It occurs during compilation, so it is not trivial to resolve by adding a test skip.

(CC @jeremyfaller for routing)

[bcmills]

So far these failures have only been seen on the freebsd-amd64-12_2 builder, but with a sample size of N=3 it isn't obvious to me whether the underlying problem may affect other platforms.

[cherrymui]

The error is probably from the linker. May be the same cause s #49752.

[prattmic]

I haven't been trying to reproduce this (I'm going after #46272 (comment)), but this has reproduced in 2/5 of my crashes so far with:

$ goswarm -i 25 freebsd-amd64-12_2 go/src/all.bash

[cherrymui]

@prattmic do you think this could be a result from the memory corruption from the other bug, or this is a different issue? Thanks.

[prattmic]

It seems plausible, but I haven't seen enough details to have confidence one way or another.

[cherrymui]

Same as #49752 . We can revisit once we have FreeBSD builders with kernel fixed.

[bcmills]

https://storage.googleapis.com/go-build-log/301db3f5/freebsd-amd64-12_2_faaeee15.log (a TryBot).

I think @heschi pushed an updated FreeBSD 13 builder today — is there a fix available for 12.2 as well?

[prattmic]

#46272 (comment) noted that the fix is cherry-picked into FreeBSD 12 as well.

I believe https://lists.freebsd.org/archives/freebsd-snapshots/2021-December/000037.html is the latest 12 snapshot.