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go/test/typeswitch2.go
Rob Pike 80a9783f84 test/[n-z]*.go: add documentation
R=golang-dev, bradfitz, r
CC=golang-dev
https://golang.org/cl/5700056
2012-02-24 11:48:19 +11:00

48 lines
998 B
Go

// errorcheck
// 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.
// Verify that various erroneous type switches are caught be the compiler.
// Does not compile.
package main
import "io"
func whatis(x interface{}) string {
switch x.(type) {
case int:
return "int"
case int: // ERROR "duplicate"
return "int8"
case io.Reader:
return "Reader1"
case io.Reader: // ERROR "duplicate"
return "Reader2"
case interface {
r()
w()
}:
return "rw"
case interface { // GCCGO_ERROR "duplicate"
w()
r()
}: // GC_ERROR "duplicate"
return "wr"
}
return ""
}
func notused(x interface{}) {
// The first t is in a different scope than the 2nd t; it cannot
// be accessed (=> declared and not used error); but it is legal
// to declare it.
switch t := 0; t := x.(type) { // ERROR "declared and not used"
case int:
_ = t // this is using the t of "t := x.(type)"
}
}