1 files changed, 64 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/gc/lang_test.go b/src/cmd/compile/internal/gc/lang_test.go
new file mode 100644
index 0000000..72e7f07
--- /dev/null
+++ b/src/cmd/compile/internal/gc/lang_test.go
@@ -0,0 +1,64 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gc
+
+import (
+	"internal/testenv"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"testing"
+)
+
+const aliasSrc = `
+package x
+
+type T = int
+`
+
+func TestInvalidLang(t *testing.T) {
+	t.Parallel()
+
+	testenv.MustHaveGoBuild(t)
+
+	dir, err := ioutil.TempDir("", "TestInvalidLang")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(dir)
+
+	src := filepath.Join(dir, "alias.go")
+	if err := ioutil.WriteFile(src, []byte(aliasSrc), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	outfile := filepath.Join(dir, "alias.o")
+
+	if testLang(t, "go9.99", src, outfile) == nil {
+		t.Error("compilation with -lang=go9.99 succeeded unexpectedly")
+	}
+
+	// This test will have to be adjusted if we ever reach 1.99 or 2.0.
+	if testLang(t, "go1.99", src, outfile) == nil {
+		t.Error("compilation with -lang=go1.99 succeeded unexpectedly")
+	}
+
+	if testLang(t, "go1.8", src, outfile) == nil {
+		t.Error("compilation with -lang=go1.8 succeeded unexpectedly")
+	}
+
+	if err := testLang(t, "go1.9", src, outfile); err != nil {
+		t.Errorf("compilation with -lang=go1.9 failed unexpectedly: %v", err)
+	}
+}
+
+func testLang(t *testing.T, lang, src, outfile string) error {
+	run := []string{testenv.GoToolPath(t), "tool", "compile", "-lang", lang, "-o", outfile, src}
+	t.Log(run)
+	out, err := exec.Command(run[0], run[1:]...).CombinedOutput()
+	t.Logf("%s", out)
+	return err
+}