1 files changed, 31 insertions, 0 deletions
diff --git a/src/cmd/pack/pack_test.go b/src/cmd/pack/pack_test.go
index 79d9cde292..b2217c090f 100644
--- a/src/cmd/pack/pack_test.go
+++ b/src/cmd/pack/pack_test.go
@@ -295,6 +295,37 @@ func TestLargeDefs(t *testing.T) {
 	}
 }
 
+// Test that "\n!\n" inside export data doesn't result in a truncated
+// package definition when creating a .a archive from a .o Go object.
+func TestIssue21703(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+
+	dir := tmpDir(t)
+	defer os.RemoveAll(dir)
+
+	const aSrc = `package a; const X = "\n!\n"`
+	err := ioutil.WriteFile(filepath.Join(dir, "a.go"), []byte(aSrc), 0666)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	const bSrc = `package b; import _ "a"`
+	err = ioutil.WriteFile(filepath.Join(dir, "b.go"), []byte(bSrc), 0666)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	run := func(args ...string) string {
+		return doRun(t, dir, args...)
+	}
+
+	goBin := testenv.GoToolPath(t)
+	run(goBin, "build", "cmd/pack") // writes pack binary to dir
+	run(goBin, "tool", "compile", "a.go")
+	run("./pack", "c", "a.a", "a.o")
+	run(goBin, "tool", "compile", "-I", ".", "b.go")
+}
+
 // doRun runs a program in a directory and returns the output.
 func doRun(t *testing.T, dir string, args ...string) string {
 	cmd := exec.Command(args[0], args[1:]...)