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mirror of https://github.com/golang/go synced 2024-11-12 07:00:21 -07:00

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
This commit is contained in:
Robert Griesemer 2011-04-14 14:25:25 -07:00
parent 881b1b4a02
commit a49e7f393f
6 changed files with 45 additions and 0 deletions

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@ -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"},
}

View File

@ -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++ {

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@ -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

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@ -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

10
src/cmd/gofmt/testdata/rewrite2.golden vendored Normal file
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@ -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 {}

10
src/cmd/gofmt/testdata/rewrite2.input vendored Normal file
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@ -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 {}