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go/test/parentype.go
Robert Griesemer 07cc6440dc go_spec: don't allow parens around the literal type of composite literals
Background: The current spec is imprecise with respect to the parsing ambiguity
for composite literals: It says that the ambiguity arises when the TypeName form
of the LiteralType is used. The following code:

    if (B) {} ...

is not using the TypeName form (but the parenthesized TypeName form) and thus
could be interpreted as:

    if ((B){}) ...

instead of

    if B {} ...

Both compilers and gofmt choose the latter interpretation. One could fix the
spec by making the clause regarding the parsing ambiguity more precise ("...using
the _possibly parenthesized_ TypeName form of the LiteralType..."). The alternative
(chosen here) is to simply disallow parenthesized literal types. Except for a single
test case (test/parentype.go) there appears to be no Go code under $GOROOT containing
parenthesized literal types. Furthermore, parentheses are never needed around a
literal type for correct parsing.

R=golang-dev
CC=golang-dev
https://golang.org/cl/1913041
2010-07-29 18:13:41 -07:00

18 lines
391 B
Go

// $G $D/$F.go
// Copyright 2009 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
func f(interface{})
func g() {}
func main() {
f(map[string]string{"a":"b","c":"d"});
f([...]int{1,2,3});
f(map[string]func(){"a":g,"c":g});
f(make(chan(<-chan int)));
f(make(chan<-(chan int)));
}