cmd/compile: add a test for reproducible build with anonymous interfaces

Duplicated anonymous interfaces caused nondeterministic build.
The fix is CL 129515. This CL adds a test.

Updates #27013.

Change-Id: I6b7e1bbfc943c22e8e6f32c145f7aebb567cef15
Reviewed-on: https://go-review.googlesource.com/129680
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/compile/internal/gc/reproduciblebuilds_test.go

@@ -15,34 +15,45 @@ import (
 )
 
 func TestReproducibleBuilds(t *testing.T) {
+	tests := []string{
+		"issue20272.go",
+		"issue27013.go",
+	}
+
 	testenv.MustHaveGoBuild(t)
 	iters := 10
 	if testing.Short() {
 		iters = 4
 	}
 	t.Parallel()
-	var want []byte
-	tmp, err := ioutil.TempFile("", "")
-	if err != nil {
-		t.Fatalf("temp file creation failed: %v", err)
-	}
-	defer os.Remove(tmp.Name())
-	defer tmp.Close()
-	for i := 0; i < iters; i++ {
-		out, err := exec.Command(testenv.GoToolPath(t), "tool", "compile", "-o", tmp.Name(), filepath.Join("testdata", "reproducible", "issue20272.go")).CombinedOutput()
-		if err != nil {
-			t.Fatalf("failed to compile: %v\n%s", err, out)
-		}
-		obj, err := ioutil.ReadFile(tmp.Name())
-		if err != nil {
-			t.Fatalf("failed to read object file: %v", err)
-		}
-		if i == 0 {
-			want = obj
-		} else {
-			if !bytes.Equal(want, obj) {
-				t.Fatalf("builds produced different output after %d iters (%d bytes vs %d bytes)", i, len(want), len(obj))
+	for _, test := range tests {
+		test := test
+		t.Run(test, func(t *testing.T) {
+			t.Parallel()
+			var want []byte
+			tmp, err := ioutil.TempFile("", "")
+			if err != nil {
+				t.Fatalf("temp file creation failed: %v", err)
+			}
+			defer os.Remove(tmp.Name())
+			defer tmp.Close()
+			for i := 0; i < iters; i++ {
+				out, err := exec.Command(testenv.GoToolPath(t), "tool", "compile", "-o", tmp.Name(), filepath.Join("testdata", "reproducible", test)).CombinedOutput()
+				if err != nil {
+					t.Fatalf("failed to compile: %v\n%s", err, out)
+				}
+				obj, err := ioutil.ReadFile(tmp.Name())
+				if err != nil {
+					t.Fatalf("failed to read object file: %v", err)
+				}
+				if i == 0 {
+					want = obj
+				} else {
+					if !bytes.Equal(want, obj) {
+						t.Fatalf("builds produced different output after %d iters (%d bytes vs %d bytes)", i, len(want), len(obj))
+					}
+				}
 			}
-		}
+		})
 	}
 }

src/cmd/compile/internal/gc/testdata/reproducible/issue27013.go

+// 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 p
+
+func A(arg interface{}) {
+	_ = arg.(interface{ Func() int32 })
+	_ = arg.(interface{ Func() int32 })
+	_ = arg.(interface{ Func() int32 })
+	_ = arg.(interface{ Func() int32 })
+	_ = arg.(interface{ Func() int32 })
+	_ = arg.(interface{ Func() int32 })
+	_ = arg.(interface{ Func() int32 })
+}