1// errorcheck 2 3// Copyright 2009 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 various erroneous type switches are caught by the compiler. 8// Does not compile. 9 10package main 11 12import "io" 13 14func whatis(x interface{}) string { 15 switch x.(type) { 16 case int: 17 return "int" 18 case int: // ERROR "duplicate" 19 return "int8" 20 case io.Reader: 21 return "Reader1" 22 case io.Reader: // ERROR "duplicate" 23 return "Reader2" 24 case interface { 25 r() 26 w() 27 }: 28 return "rw" 29 case interface { // ERROR "duplicate" 30 w() 31 r() 32 }: 33 return "wr" 34 35 } 36 return "" 37} 38