cmd/gofmt: handle ... in rewrite of calls

Fixes #5059.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/8284043

src/cmd/gofmt/gofmt_test.go

@@ -82,6 +82,8 @@ var tests = []struct {
 	{"testdata/rewrite3.input", "-r=x->x"},
 	{"testdata/rewrite4.input", "-r=(x)->x"},
 	{"testdata/rewrite5.input", "-r=x+x->2*x"},
+	{"testdata/rewrite6.input", "-r=fun(x)->Fun(x)"},
+	{"testdata/rewrite7.input", "-r=fun(x...)->Fun(x)"},
 	{"testdata/stdin*.input", "-stdin"},
 	{"testdata/comments.input", ""},
 	{"testdata/import.input", ""},

src/cmd/gofmt/rewrite.go

@@ -107,6 +107,7 @@ var (
 	identType     = reflect.TypeOf((*ast.Ident)(nil))
 	objectPtrType = reflect.TypeOf((*ast.Object)(nil))
 	positionType  = reflect.TypeOf(token.NoPos)
+	callExprType  = reflect.TypeOf((*ast.CallExpr)(nil))
 	scopePtrType  = reflect.TypeOf((*ast.Scope)(nil))
 )
 
@@ -192,8 +193,17 @@ func match(m map[string]reflect.Value, pattern, val reflect.Value) bool {
 		v := val.Interface().(*ast.Ident)
 		return p == nil && v == nil || p != nil && v != nil && p.Name == v.Name
 	case objectPtrType, positionType:
-		// object pointers and token positions don't need to match
+		// object pointers and token positions always match
 		return true
+	case callExprType:
+		// For calls, the Ellipsis fields (token.Position) must
+		// match since that is how f(x) and f(x...) are different.
+		// Check them here but fall through for the remaining fields.
+		p := pattern.Interface().(*ast.CallExpr)
+		v := val.Interface().(*ast.CallExpr)
+		if p.Ellipsis.IsValid() != v.Ellipsis.IsValid() {
+			return false
+		}
 	}
 
 	p := reflect.Indirect(pattern)

src/cmd/gofmt/testdata/rewrite6.golden

+// Copyright 2013 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.
+
+// Rewriting of calls must take the ... (ellipsis)
+// attribute for the last argument into account.
+
+package p
+
+func fun(x []int) {}
+
+func g(x []int) {
+	Fun(x)    // -r='fun(x)->Fun(x)' should rewrite this to Fun(x)
+	fun(x...) // -r='fun(x)->Fun(x)' should not rewrite this
+}

src/cmd/gofmt/testdata/rewrite6.input

+// Copyright 2013 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.
+
+// Rewriting of calls must take the ... (ellipsis)
+// attribute for the last argument into account.
+
+package p
+
+func fun(x []int) {}
+
+func g(x []int) {
+	fun(x)    // -r='fun(x)->Fun(x)' should rewrite this to Fun(x)
+	fun(x...) // -r='fun(x)->Fun(x)' should not rewrite this
+}

src/cmd/gofmt/testdata/rewrite7.golden

+// Copyright 2013 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.
+
+// Rewriting of calls must take the ... (ellipsis)
+// attribute for the last argument into account.
+
+package p
+
+func fun(x []int) {}
+
+func g(x []int) {
+	fun(x) // -r='fun(x...)->Fun(x)' should not rewrite this
+	Fun(x) // -r='fun(x...)->Fun(x)' should rewrite this to Fun(x)
+}

src/cmd/gofmt/testdata/rewrite7.input

+// Copyright 2013 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.
+
+// Rewriting of calls must take the ... (ellipsis)
+// attribute for the last argument into account.
+
+package p
+
+func fun(x []int) {}
+
+func g(x []int) {
+	fun(x)    // -r='fun(x...)->Fun(x)' should not rewrite this
+	fun(x...) // -r='fun(x...)->Fun(x)' should rewrite this to Fun(x)
+}