From a49e7f393fe62d97dae691fdada7ab134fb83b6b Mon Sep 17 00:00:00 2001
From: Robert Griesemer <gri@golang.org>
Date: Thu, 14 Apr 2011 14:25:25 -0700
Subject: [PATCH] gofmt: don't crash when rewriting nil interfaces in AST.
The new reflection API makes it an error to call value.Set(x)
if x is invalid. Guard for it.
Added corresponding test case.
Fixes #1696.
R=rsc, r
CC=golang-dev
https://golang.org/cl/4398047
---
src/cmd/gofmt/gofmt_test.go | 1 +
src/cmd/gofmt/rewrite.go | 16 ++++++++++++++++
src/cmd/gofmt/testdata/rewrite1.golden | 4 ++++
src/cmd/gofmt/testdata/rewrite1.input | 4 ++++
src/cmd/gofmt/testdata/rewrite2.golden | 10 ++++++++++
src/cmd/gofmt/testdata/rewrite2.input | 10 ++++++++++
6 files changed, 45 insertions(+)
create mode 100644 src/cmd/gofmt/testdata/rewrite2.golden
create mode 100644 src/cmd/gofmt/testdata/rewrite2.input
diff --git a/src/cmd/gofmt/gofmt_test.go b/src/cmd/gofmt/gofmt_test.go
index 4ec94e29330..a72530307ee 100644
--- a/src/cmd/gofmt/gofmt_test.go
+++ b/src/cmd/gofmt/gofmt_test.go
@@ -71,6 +71,7 @@ var tests = []struct {
{".", "gofmt_test.go", "gofmt_test.go", ""},
{"testdata", "composites.input", "composites.golden", "-s"},
{"testdata", "rewrite1.input", "rewrite1.golden", "-r=Foo->Bar"},
+ {"testdata", "rewrite2.input", "rewrite2.golden", "-r=int->bool"},
}
diff --git a/src/cmd/gofmt/rewrite.go b/src/cmd/gofmt/rewrite.go
index 93643dced25..631c513310c 100644
--- a/src/cmd/gofmt/rewrite.go
+++ b/src/cmd/gofmt/rewrite.go
@@ -63,6 +63,10 @@ func rewriteFile(pattern, replace ast.Expr, p *ast.File) *ast.File {
repl := reflect.NewValue(replace)
var f func(val reflect.Value) reflect.Value // f is recursive
f = func(val reflect.Value) reflect.Value {
+ // don't bother if val is invalid to start with
+ if !val.IsValid() {
+ return reflect.Value{}
+ }
for k := range m {
m[k] = reflect.Value{}, false
}
@@ -79,6 +83,10 @@ func rewriteFile(pattern, replace ast.Expr, p *ast.File) *ast.File {
// setValue is a wrapper for x.SetValue(y); it protects
// the caller from panics if x cannot be changed to y.
func setValue(x, y reflect.Value) {
+ // don't bother if y is invalid to start with
+ if !y.IsValid() {
+ return
+ }
defer func() {
if x := recover(); x != nil {
if s, ok := x.(string); ok && strings.HasPrefix(s, "type mismatch") {
@@ -95,10 +103,12 @@ func setValue(x, y reflect.Value) {
// Values/types for special cases.
var (
objectPtrNil = reflect.NewValue((*ast.Object)(nil))
+ scopePtrNil = reflect.NewValue((*ast.Scope)(nil))
identType = reflect.Typeof((*ast.Ident)(nil))
objectPtrType = reflect.Typeof((*ast.Object)(nil))
positionType = reflect.Typeof(token.NoPos)
+ scopePtrType = reflect.Typeof((*ast.Scope)(nil))
)
@@ -115,6 +125,12 @@ func apply(f func(reflect.Value) reflect.Value, val reflect.Value) reflect.Value
return objectPtrNil
}
+ // similarly for scopes: they are likely incorrect after a rewrite;
+ // replace them with nil
+ if val.Type() == scopePtrType {
+ return scopePtrNil
+ }
+
switch v := reflect.Indirect(val); v.Kind() {
case reflect.Slice:
for i := 0; i < v.Len(); i++ {
diff --git a/src/cmd/gofmt/testdata/rewrite1.golden b/src/cmd/gofmt/testdata/rewrite1.golden
index 3f909ff4ad2..d9beb370582 100644
--- a/src/cmd/gofmt/testdata/rewrite1.golden
+++ b/src/cmd/gofmt/testdata/rewrite1.golden
@@ -1,3 +1,7 @@
+// Copyright 2011 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 main
type Bar int
diff --git a/src/cmd/gofmt/testdata/rewrite1.input b/src/cmd/gofmt/testdata/rewrite1.input
index 1f10e3601cf..bdb894320d3 100644
--- a/src/cmd/gofmt/testdata/rewrite1.input
+++ b/src/cmd/gofmt/testdata/rewrite1.input
@@ -1,3 +1,7 @@
+// Copyright 2011 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 main
type Foo int
diff --git a/src/cmd/gofmt/testdata/rewrite2.golden b/src/cmd/gofmt/testdata/rewrite2.golden
new file mode 100644
index 00000000000..64c67ffa67b
--- /dev/null
+++ b/src/cmd/gofmt/testdata/rewrite2.golden
@@ -0,0 +1,10 @@
+// Copyright 2011 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
+
+// Slices have nil Len values in the corresponding ast.ArrayType
+// node and reflect.NewValue(slice.Len) is an invalid reflect.Value.
+// The rewriter must not crash in that case. Was issue 1696.
+func f() []bool {}
diff --git a/src/cmd/gofmt/testdata/rewrite2.input b/src/cmd/gofmt/testdata/rewrite2.input
new file mode 100644
index 00000000000..21171447a10
--- /dev/null
+++ b/src/cmd/gofmt/testdata/rewrite2.input
@@ -0,0 +1,10 @@
+// Copyright 2011 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
+
+// Slices have nil Len values in the corresponding ast.ArrayType
+// node and reflect.NewValue(slice.Len) is an invalid reflect.Value.
+// The rewriter must not crash in that case. Was issue 1696.
+func f() []int {}
--
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