Add flag to disable gotags filtering

[codersasha]

What version of gazelle are you using?

v0.28.0

What version of rules_go are you using?

v0.37.0

What version of Bazel are you using?

5.4.0

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

Yes

What operating system and processor architecture are you using?

Ubuntu 22.04.1 LTS

What did you do?

As of #1243, the latest version of Gazelle automatically filers out files without gotags set. This means that one of my libraries has gone from:

go_library(
    name = "library",
    srcs = [
        "config.go",
        "defaults.go",
        "defaults_local.go",
        "defaults_not_local.go",
    ],
    importpath = "my/path/to/library",
    visibility = ["//visibility:public"],
)

to

go_library(
    name = "library",
    srcs = [
        "config.go",
        "defaults.go",
        "defaults_not_local.go",
    ],
    importpath = "my/path/to/library",
    visibility = ["//visibility:public"],
)

The contents of defaults_local.go is:

//go:build local

package library

var getName = func(name Name) string {
	return "a"
}

And the contents of defaults_not_local.go is:

//go:build !local

package library

var getName = func(name Name) string {
	return "b"
}

This library is then used to build two go_binary targets:

go_binary(
    name ="library_bin",
    embed = [":library"],
)

go_binary(
    name ="library_local_bin",
    gotags = ["local"],
    embed = [":library"],
)

What did you expect to see?

I expected to be able to run both binary targets (bazel run //:library_bin and bazel run //:library_local_bin).

What did you see instead?

bazel run //:library_local_bin now fails with getName is not defined, because defaults_local.go has been removed from the dependencies.

If I configure gazelle to use -gotags=local for all targets, then the other target breaks, since defaults_not_local.go is now excluded.

Given this is a common pattern, it would be good to have a way of disabling the gotags filtering behaviour, so I can include both sources in the target definition, but switch between them at go_binary build time. Alternatively, Gazelle would need a way of generating two libraries, one with the build tag and one without it.

[t0rr3sp3dr0]

Any luck finding a workaround for this?

[dtkpp]

We have a wrapper rule around the standard go_library rule in Bazel which simply replaces source code files. This force includes both files in go.

Define a new loadable rule with bazel.

Project definition path.

/project/bazel/go_library/def.bzl

load("@io_bazel_rules_go//go:def.bzl", "go_library")

def my_go_library(name, **kwargs):
   srcs = kwargs.pop("srcs", []) + native.glob(["*_local.go"], exclude = ["*_not_local.go"])
   go_library(
      name = name,
      srcs = srcs,
       **kwargs
   )

Define in gazelle run as a directive.

# gazelle:map_kind go_library my_go_library //project/bazel/go_library:def.bzl
gazelle(name = "gazelle")