feat(mode): add purego tag when pure

The community has agreed[1] that "pure" builds of Go code should
use the `purego` build tag.

This change adds that de-facto tag.

The minimum version of Gazelle is bumped to `0.36.0` which includes a patch[2]
for ignoring the `purego` tag so that the source flies are passed to the
compiler for conditional compilation decisions.

[1]: golang/go#23172
[2]: bazelbuild/bazel-gazelle#1767

.bazelci/presubmit.yml

@@ -62,6 +62,7 @@ tasks:
  - "//..."
  bcr_tests:
  name: BCR test module
+ bazel: 6.3.0 # silent ignore override in `gazelle@0.36.0`
  platform: ${{ platform }}
  working_directory: tests/bcr
  build_flags:

MODULE.bazel

@@ -27,7 +27,7 @@ use_repo(
 
 register_toolchains("@go_toolchains//:all")
 
-bazel_dep(name = "gazelle", version = "0.34.0")
+bazel_dep(name = "gazelle", version = "0.36.0")
 
 go_deps = use_extension("@gazelle//:extensions.bzl", "go_deps")
 go_deps.from_file(go_mod = "//:go.mod")

WORKSPACE

@@ -71,10 +71,10 @@ bazel_skylib_workspace()
 
 http_archive(
  name = "bazel_gazelle",
- sha256 = "b7387f72efb59f876e4daae42f1d3912d0d45563eac7cb23d1de0b094ab588cf",
+ sha256 = "75df288c4b31c81eb50f51e2e14f4763cb7548daae126817247064637fd9ea62",
  urls = [
- "https://mirror.bazel.build/github.com/bazelbuild/bazel-gazelle/releases/download/v0.34.0/bazel-gazelle-v0.34.0.tar.gz",
- "https://github.com/bazelbuild/bazel-gazelle/releases/download/v0.34.0/bazel-gazelle-v0.34.0.tar.gz",
+ "https://mirror.bazel.build/github.com/bazelbuild/bazel-gazelle/releases/download/v0.36.0/bazel-gazelle-v0.36.0.tar.gz",
+ "https://github.com/bazelbuild/bazel-gazelle/releases/download/v0.36.0/bazel-gazelle-v0.36.0.tar.gz",
  ],
 )
 

go/modes.rst

@@ -68,6 +68,8 @@ or using `Bazel configuration transitions`_.
 | Disables cgo, even when a C/C++ toolchain is configured (similar to setting |
 | ``CGO_ENABLED=0``). Packages that contain cgo code may still be built, but |
 | the cgo code will be filtered out, and the ``cgo`` build tag will be false. |
+| Sets the de-facto ``purego`` build tag for conditional inclusion of source |
+| files. |
 +-------------------+---------------------+------------------------------------+
 | :param:`debug` | :type:`bool` | :value:`false` |
 +-------------------+---------------------+------------------------------------+

go/private/mode.bzl

@@ -122,6 +122,8 @@ def get_mode(ctx, go_toolchain, cgo_context_info, go_config_info):
  tags.append("race")
  if msan:
  tags.append("msan")
+ if pure:
+ tags.append("purego")
 
  return struct(
  static = static,

tests/core/cgo/BUILD.bazel

@@ -334,6 +334,7 @@ go_test(
  data = [
  ":tag_cgo_bin",
  ":tag_pure_bin",
+ ":tag_purego_bin",
  ],
  rundir = ".",
  deps = ["//go/tools/bazel:go_default_library"],
@@ -350,6 +351,17 @@ go_binary(
  pure = "on",
 )
 
+go_binary(
+ name = "tag_purego_bin",
+ srcs = [
+ "tag_purego.go",
+ "tag_purego_err.c",
+ "tag_purego_err.go",
+ ],
+ cgo = True,
+ pure = "on",
+)
+
 go_binary(
  name = "tag_cgo_bin",
  srcs = [

tests/core/cgo/tag_purego.go

@@ -0,0 +1,9 @@
+// +build purego
+
+package main
+
+import "fmt"
+
+func main() {
+ fmt.Println("purego")
+}

tests/core/cgo/tag_purego_err.c

@@ -0,0 +1 @@
+#error should not be compiled

tests/core/cgo/tag_purego_err.go

@@ -0,0 +1,6 @@
+// +build !purego
+
+package main
+
+// this file should not be compiled
+!!!

tests/core/cgo/tag_test.go

@@ -15,6 +15,9 @@ func Test(t *testing.T) {
  {
  name: "tag_pure_bin",
  want: "pure",
+ }, {
+ name: "tag_purego_bin",
+ want: "purego",
  }, {
  name: "tag_cgo_bin",
  want: "cgo",

tests/integration/gazelle/gazelle_test.go

@@ -53,8 +53,8 @@ func TestUpdate(t *testing.T) {
  }
  got := strings.TrimSpace(string(data))
  want := strings.TrimSpace(`
-load("@io_bazel_rules_go//go:def.bzl", "go_library")
 load("@bazel_gazelle//:def.bzl", "gazelle")
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
 
 # gazelle:prefix example.com/hello
 gazelle(

third_party/org_golang_google_protobuf-gazelle.patch

@@ -1556,7 +1556,7 @@ diff -urN a/internal/genid/BUILD.bazel b/internal/genid/BUILD.bazel
 diff -urN a/internal/impl/BUILD.bazel b/internal/impl/BUILD.bazel
 --- a/internal/impl/BUILD.bazel 1970-01-01 00:00:00.000000000 +0000
 +++ b/internal/impl/BUILD.bazel 2000-01-01 00:00:00.000000000 -0000
-@@ -0,0 +1,111 @@
+@@ -0,0 +1,113 @@
 +load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
 +
 +go_library(
@@ -1572,6 +1572,7 @@ diff -urN a/internal/impl/BUILD.bazel b/internal/impl/BUILD.bazel
 + "codec_map_go112.go",
 + "codec_message.go",
 + "codec_messageset.go",
++ "codec_reflect.go",
 + "codec_tables.go",
 + "codec_unsafe.go",
 + "convert.go",
@@ -1592,6 +1593,7 @@ diff -urN a/internal/impl/BUILD.bazel b/internal/impl/BUILD.bazel
 + "message_reflect.go",
 + "message_reflect_field.go",
 + "message_reflect_gen.go",
++ "pointer_reflect.go",
 + "pointer_unsafe.go",
 + "validate.go",
 + "weak.go",
@@ -1838,13 +1840,14 @@ diff -urN a/internal/set/BUILD.bazel b/internal/set/BUILD.bazel
 diff -urN a/internal/strs/BUILD.bazel b/internal/strs/BUILD.bazel
 --- a/internal/strs/BUILD.bazel 1970-01-01 00:00:00.000000000 +0000
 +++ b/internal/strs/BUILD.bazel 2000-01-01 00:00:00.000000000 -0000
-@@ -0,0 +1,27 @@
+@@ -0,0 +1,28 @@
 +load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
 +
 +go_library(
 + name = "strs",
 + srcs = [
 + "strings.go",
++ "strings_pure.go",
 + "strings_unsafe.go",
 + ],
 + importpath = "google.golang.org/protobuf/internal/strs",
@@ -3092,7 +3095,7 @@ diff -urN a/reflect/protorange/BUILD.bazel b/reflect/protorange/BUILD.bazel
 diff -urN a/reflect/protoreflect/BUILD.bazel b/reflect/protoreflect/BUILD.bazel
 --- a/reflect/protoreflect/BUILD.bazel 1970-01-01 00:00:00.000000000 +0000
 +++ b/reflect/protoreflect/BUILD.bazel 2000-01-01 00:00:00.000000000 -0000
-@@ -0,0 +1,38 @@
+@@ -0,0 +1,39 @@
 +load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
 +
 +go_library(
@@ -3105,6 +3108,7 @@ diff -urN a/reflect/protoreflect/BUILD.bazel b/reflect/protoreflect/BUILD.bazel
 + "type.go",
 + "value.go",
 + "value_equal.go",
++ "value_pure.go",
 + "value_union.go",
 + "value_unsafe.go",
 + ],