go_tool_binary / GoToolchainBinaryBuild actions don't always run on the correct platform

[EdSchouten]

What version of rules_go are you using?

0.47.1

What version of gazelle are you using?

n/a

What version of Bazel are you using?

7.0.2

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

Yes.

What operating system and processor architecture are you using?

Remote execution cluster that has Linux x86_64 workers, in combination with a macOS client.

Any other potentially useful information about your toolchain?

n/a

What did you do?

I ran a Bazel build with the following flag set:

--extra_execution_platforms=//some/linux/platform,//some/macos/platform

During the build, it had to compile a Go binary for macOS (i.e., some tool to eventually run on the host platform). This ended up failing, because it had to run a GoToolchainBinaryBuild action. This action ended up getting run on the Linux workers, because it was the first platform in the list. There it failed with error:

/bin/bash: line 1: external/go_sdk/bin/go: cannot execute binary file: Exec format error

What did you expect to see?

That it ran the action on my local system.

What did you see instead?

That it attempted to run a copy of Go for macOS on the Linux workers.

I think that the root cause is that the go_tool_binary rule has absolutely no logic in place to ensure that an execution platform is used that matches up with the copy of the Go SDK. I tried to work around this by adding:

toolchains = ["@io_bazel_rules_go//go:toolchain"],

But this fails due to a cyclic dependency:

    ...
    @@go_sdk//:go_darwin_amd64-impl (c55e8f4de7cab132a0f1e0fde73344500194ac1db34f6fc75005ccf41302d350)
.-> @@go_sdk//:builder_reset (ca07856a6315d9ce49d448350dcbda8b02b33c99dce524cc4378883f88bd1701)
|   @@go_sdk//:builder (ca07856a6315d9ce49d448350dcbda8b02b33c99dce524cc4378883f88bd1701)
|   @@go_sdk//:go_darwin_amd64-impl (ca07856a6315d9ce49d448350dcbda8b02b33c99dce524cc4378883f88bd1701)
`-- @@go_sdk//:builder_reset (ca07856a6315d9ce49d448350dcbda8b02b33c99dce524cc4378883f88bd1701)