go_proto_library output is not reproducible on different host platforms

[Illedran]

What version of rules_go are you using?

0.48.1

What version of gazelle are you using?

0.37.0

What version of Bazel are you using?

7.2.1

Does this issue reproduce with the latest releases of all the above?

Those are the latest releases as of time of writing.

What operating system and processor architecture are you using?

Tried on Darwin/Linux, resp:

$ uname -sm
Darwin arm64

$ uname -sm
Linux x86_64

Any other potentially useful information about your toolchain?

See reproducer: https://github.com/Illedran/go_cross_reproducible

What did you do?

In the reproducer: bazel build //:cross. Inspecting the output of go_proto_library, in the transition triggered by go_cross_binary:

# Darwin
$ md5 bazel-out/darwin_arm64-fastbuild-ST-2c62b798ec6c/bin/proto/proto.a
MD5 (bazel-out/darwin_arm64-fastbuild-ST-2c62b798ec6c/bin/proto/proto.a) = c12605aa69aea711f341eab796689bff

# Linux
$ md5sum bazel-out/k8-fastbuild-ST-2c62b798ec6c/bin/proto/proto.a 
d3fd7a4e36f011b221e743132ff41c03  bazel-out/k8-fastbuild-ST-2c62b798ec6c/bin/proto/proto.a

A diff of those archives using diffoscope can be seen at https://try.diffoscope.org/xhsafcfsqkpf.html - but it's actually easier to see the problem on the final resulting binaries https://try.diffoscope.org/tpbcfezvbhvh.html, where it appears that part of path that is dependant on the host platform "leaks" into the final binary.

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