cmd/go: allow all build flags for tool

[howardjohn]

Go version

latest

Output of go env in your module/workspace:

N/A

What did you do?

go tool .... <any number of flags>

What did you see happen?

The command supports on a very minimal set of flags (which are not documented, fwiw #71502). All(?) other commands in the Go toolchain support a large range of flags to customize, troubleshoot, etc.

In particular, go run does, which feels like a very close parallel to go tool. It seems odd I can do -x to debug go run but not go tool, for instance.

What did you expect to see?

All build flags available.

Note: -n is in conflict, though.

[gabyhelp]

Related Issues

• cmd/go: missing flags in help output for tool #71502

Related Code Changes

• cmd/go: document that go generate accepts all build flags

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[matloob]

cc @ConradIrwin

I think this is reasonable to do, we'd just have to make sure we're adding the right set of flags. All we'd have to do is to call work.AddBuildFlags (with the appropriate BuildFlagMask).

[ConradIrwin]

Seems reasonable to me; I didn't add them originally because it seemed out of scope (go tool --flag-flag-flag is no longer a useful time saver, and you're back to needing a wrapper script or be a one off).

That said, I don't see any downside

[matloob]

@howardjohn do you have a use case for the flags other than -n and -x? Maybe we can start by just adding those?

I agree that the usefulness of providing several flags to go tool seems limited.

[seankhliao]

you could maybe pass in build flags with GOFLAGS if necessary for debugging.

[seankhliao]

I saw a comment somewhere about being unable to use golang-migrate/migrate, which uses -tags to build with support for different database drivers https://github.com/golang-migrate/migrate/tree/master/cmd/migrate

[seankhliao]

we just had an issue filed for tags, to use with migrate #73347

[yshngg]

we just had an issue filed for tags, to use with migrate #73347

@seankhliao, certainly, I have an alternative solution: enabling default builds of specific database drivers when the -tags flag is not specified (refer to golang-migrate/migrate#1255).

However, this approach lack flexibility.