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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
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@ -71,6 +71,7 @@ var tests = []struct {
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{".", "gofmt_test.go", "gofmt_test.go", ""},
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{"testdata", "composites.input", "composites.golden", "-s"},
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{"testdata", "rewrite1.input", "rewrite1.golden", "-r=Foo->Bar"},
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{"testdata", "rewrite2.input", "rewrite2.golden", "-r=int->bool"},
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}
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@ -63,6 +63,10 @@ func rewriteFile(pattern, replace ast.Expr, p *ast.File) *ast.File {
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repl := reflect.NewValue(replace)
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var f func(val reflect.Value) reflect.Value // f is recursive
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f = func(val reflect.Value) reflect.Value {
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// don't bother if val is invalid to start with
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if !val.IsValid() {
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return reflect.Value{}
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}
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for k := range m {
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m[k] = reflect.Value{}, false
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}
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@ -79,6 +83,10 @@ func rewriteFile(pattern, replace ast.Expr, p *ast.File) *ast.File {
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// setValue is a wrapper for x.SetValue(y); it protects
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// the caller from panics if x cannot be changed to y.
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func setValue(x, y reflect.Value) {
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// don't bother if y is invalid to start with
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if !y.IsValid() {
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return
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}
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defer func() {
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if x := recover(); x != nil {
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if s, ok := x.(string); ok && strings.HasPrefix(s, "type mismatch") {
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@ -95,10 +103,12 @@ func setValue(x, y reflect.Value) {
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// Values/types for special cases.
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var (
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objectPtrNil = reflect.NewValue((*ast.Object)(nil))
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scopePtrNil = reflect.NewValue((*ast.Scope)(nil))
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identType = reflect.Typeof((*ast.Ident)(nil))
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objectPtrType = reflect.Typeof((*ast.Object)(nil))
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positionType = reflect.Typeof(token.NoPos)
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scopePtrType = reflect.Typeof((*ast.Scope)(nil))
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)
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@ -115,6 +125,12 @@ func apply(f func(reflect.Value) reflect.Value, val reflect.Value) reflect.Value
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return objectPtrNil
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}
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// similarly for scopes: they are likely incorrect after a rewrite;
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// replace them with nil
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if val.Type() == scopePtrType {
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return scopePtrNil
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}
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switch v := reflect.Indirect(val); v.Kind() {
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case reflect.Slice:
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for i := 0; i < v.Len(); i++ {
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4
src/cmd/gofmt/testdata/rewrite1.golden
vendored
4
src/cmd/gofmt/testdata/rewrite1.golden
vendored
@ -1,3 +1,7 @@
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// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package main
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type Bar int
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4
src/cmd/gofmt/testdata/rewrite1.input
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4
src/cmd/gofmt/testdata/rewrite1.input
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@ -1,3 +1,7 @@
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// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package main
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type Foo int
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10
src/cmd/gofmt/testdata/rewrite2.golden
vendored
Normal file
10
src/cmd/gofmt/testdata/rewrite2.golden
vendored
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@ -0,0 +1,10 @@
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// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package p
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// Slices have nil Len values in the corresponding ast.ArrayType
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// node and reflect.NewValue(slice.Len) is an invalid reflect.Value.
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// The rewriter must not crash in that case. Was issue 1696.
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func f() []bool {}
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src/cmd/gofmt/testdata/rewrite2.input
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Normal file
10
src/cmd/gofmt/testdata/rewrite2.input
vendored
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@ -0,0 +1,10 @@
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// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package p
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// Slices have nil Len values in the corresponding ast.ArrayType
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// node and reflect.NewValue(slice.Len) is an invalid reflect.Value.
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// The rewriter must not crash in that case. Was issue 1696.
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func f() []int {}
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