gcc/testsuite/go.test/test/typeswitch3.go

   1 // errorcheck
   2
   3 // Copyright 2011 The Go Authors. All rights reserved.
   4 // Use of this source code is governed by a BSD-style
   5 // license that can be found in the LICENSE file.
   6
   7 // Verify that erroneous type switches are caught be the compiler.
   8 // Issue 2700, among other things.
   9 // Does not compile.
  10
  11 package main
  12
  13 import (
  14         "io"
  15 )
  16
  17 type I interface {
  18         M()
  19 }
  20
  21 func main(){
  22         var x I
  23         switch x.(type) {
  24         case string:    // ERROR "impossible"
  25                 println("FAIL")
  26         }
  27
  28         // Issue 2700: if the case type is an interface, nothing is impossible
  29
  30         var r io.Reader
  31
  32         _, _ = r.(io.Writer)
  33
  34         switch r.(type) {
  35         case io.Writer:
  36         }
  37
  38         // Issue 2827.
  39         switch _ := r.(type) {  // ERROR "invalid variable name _|no new variables"
  40         }
  41 }
  42
  43