cmd/link: write buildid to plugin

Currently, in plugin build mode we don't write the build ID. This
is disabled in CL 29394 since plugin is supported on Darwin. Maybe
it caused some problem with the Darwin dynamic linker. But it
seems no problem currently. Enabled it.

Fixes #59845.

Change-Id: I60589ffc7937e4d30055960d391cac1e7cd0cd42
Reviewed-on: https://go-review.googlesource.com/c/go/+/489457
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>

1 files changed, 14 insertions, 2 deletions

diff --git a/misc/cgo/testplugin/plugin_test.go b/misc/cgo/testplugin/plugin_test.go
index 285681018a..8960694351 100644
--- a/misc/cgo/testplugin/plugin_test.go
+++ b/misc/cgo/testplugin/plugin_test.go
@@ -116,11 +116,15 @@ func testMain(m *testing.M) int {
 	return m.Run()
 }
 
-func goCmd(t *testing.T, op string, args ...string) {
+func goCmd(t *testing.T, op string, args ...string) string {
 	if t != nil {
 		t.Helper()
 	}
-	run(t, filepath.Join(goroot, "bin", "go"), append([]string{op, "-gcflags", gcflags}, args...)...)
+	var flags []string
+	if op != "tool" {
+		flags = []string{"-gcflags", gcflags}
+	}
+	return run(t, filepath.Join(goroot, "bin", "go"), append(append([]string{op}, flags...), args...)...)
 }
 
 // escape converts a string to something suitable for a shell command line.
@@ -190,6 +194,14 @@ func TestDWARFSections(t *testing.T) {
 	goCmd(t, "run", "./checkdwarf/main.go", "./host.exe", "main.main")
 }
 
+func TestBuildID(t *testing.T) {
+	// check that plugin has build ID.
+	b := goCmd(t, "tool", "buildid", "plugin1.so")
+	if len(b) == 0 {
+		t.Errorf("build id not found")
+	}
+}
+
 func TestRunHost(t *testing.T) {
 	run(t, "./host.exe")
 }