misc/cgo/testshared: test build std in shared mode

Test that "go install -buildmode=shared std" works.

For #57334.

Change-Id: I465a07cf2e9035995916ef9940b4c1eeba998099
Reviewed-on: https://go-review.googlesource.com/c/go/+/459056
Reviewed-by: Than McIntosh <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Tim Scharfenort <[email protected]>
Run-TryBot: Cherry Mui <[email protected]>

Author: cherrymui

misc/cgo/testshared/shared_test.go

@@ -1105,3 +1105,15 @@ func TestIssue47873(t *testing.T) {
 	goCmd(t, "install", "-buildmode=shared", "-linkshared", "./issue47837/a")
 	goCmd(t, "run", "-linkshared", "./issue47837/main")
 }
+
+// Test that we can build std in shared mode.
+func TestStd(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skip in short mode")
+	}
+	t.Parallel()
+	// Use a temporary pkgdir to not interfere with other tests, and not write to GOROOT.
+	// Cannot use goCmd as it runs with cloned GOROOT which is incomplete.
+	runWithEnv(t, "building std", []string{"GOROOT=" + oldGOROOT},
+		filepath.Join(oldGOROOT, "bin", "go"), "install", "-buildmode=shared", "-pkgdir="+t.TempDir(), "std")
+}