cmd/dist: internal import detection is generating false positives

[4a6f656c]

After updating the Go port for OpenBSD to start testing 1.23rc2, the build fails with:

===>  Building for go-1.23rc2
Building Go cmd/dist using /usr/ports/pobj/go-1.23rc2/go-openbsd-amd64-bootstrap. (go1.22.5 openbsd/amd64)
Building Go toolchain1 using /usr/ports/pobj/go-1.23rc2/go-openbsd-amd64-bootstrap.
go tool dist: /usr/ports/pobj/go-1.23rc2/go/src/cmd/internal/obj/x86/asm_test.go.orig.port:10: bootstrap-copied source file cannot import internal/testenv

This appears to be a result of code added in 805f6b3, combined with the fact that the OpenBSD ports build applies patches (and hence patch produces a backup .orig.port file). This approach has worked without issue for Go 1.22 (and every earlier version) - the new code seems to be unnecessarily excessive since this is not a .go file, does not have any build tags and is additionally test code.

In order to avoid packaging complications, can we restrict this check to files that Go will actually compile?

[ianlancetaylor]

Rather than try to have cmd/dist predict how the tools might change in the future, we have a list of ignored file prefixes and suffixes (ignorePrefixes and ignoreSuffixes in cmd/dist/buildtool.go. I suppose we could extend one of those lists.

[ianlancetaylor]

As far as I know .orig.port is not a normal output of the patch program. How hard would it be for the OpenBSD process to use a different file name? It's not clear to me that the Go build process needs to work with unexpected files sprinkled into the tree.

[4a6f656c]

The .orig.port extension is used by OpenBSD's ports in order to avoid conflicts with .orig files that are bundled:

https://man.openbsd.org/bsd.port.mk.5#PATCHORIG

This could be changed back to the patch(1) default of .orig for the lang/go port if need be.

It seems a bit strange that the general Go source file rules are not applied here, but I can provide a diff that adds .orig to the ignoreSuffixes list if that is the preferred option.

[ianlancetaylor]

I would be OK with changing bootstrapFixImports to only run on files whose names end with .go.