1 // errorcheck 2 3 // Copyright 2016 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 switch statements with duplicate cases are detected by the compiler. 8 // Does not compile. 9 10 package main 11 12 func f0(x int) { 13 switch x { 14 case 0: 15 case 0: // ERROR "duplicate case 0 in switch" 16 } 17 18 switch x { 19 case 0: 20 case int(0): // ERROR "duplicate case int.0. .value 0. in switch" 21 } 22 } 23 24 func f1(x float32) { 25 switch x { 26 case 5: 27 case 5: // ERROR "duplicate case 5 in switch" 28 case 5.0: // ERROR "duplicate case 5 in switch" 29 } 30 } 31 32 func f2(s string) { 33 switch s { 34 case "": 35 case "": // ERROR "duplicate case .. in switch" 36 case "abc": 37 case "abc": // ERROR "duplicate case .abc. in switch" 38 } 39 } 40 41 func f3(e interface{}) { 42 switch e { 43 case 0: 44 case 0: // ERROR "duplicate case 0 in switch" 45 case int64(0): 46 case float32(10): 47 case float32(10): // ERROR "duplicate case float32\(10\) .value 10. in switch" 48 case float64(10): 49 case float64(10): // ERROR "duplicate case float64\(10\) .value 10. in switch" 50 } 51 } 52 53 func f5(a [1]int) { 54 switch a { 55 case [1]int{0}: 56 case [1]int{0}: // OK -- see issue 15896 57 } 58 } 59 60 // Ensure duplicate const bool clauses are accepted. 61 func f6() int { 62 switch { 63 case 0 == 0: 64 return 0 65 case 1 == 1: // Intentionally OK, even though a duplicate of the above const true 66 return 1 67 } 68 return 2 69 } 70 71 // Ensure duplicates in ranges are detected (issue #17517). 72 func f7(a int) { 73 switch a { 74 case 0: 75 case 0, 1: // ERROR "duplicate case 0" 76 case 1, 2, 3, 4: // ERROR "duplicate case 1" 77 } 78 } 79 80 // Ensure duplicates with simple literals are printed as they were 81 // written, not just their values. Particularly useful for runes. 82 func f8(r rune) { 83 const x = 10 84 switch r { 85 case 33, 33: // ERROR "duplicate case 33 in switch" 86 case 34, '"': // ERROR "duplicate case '"' .value 34. in switch" 87 case 35, rune('#'): // ERROR "duplicate case rune.'#'. .value 35. in switch" 88 case 36, rune(36): // ERROR "duplicate case rune.36. .value 36. in switch" 89 case 37, '$'+1: // ERROR "duplicate case '\$' \+ 1 .value 37. in switch" 90 case 'b': 91 case 'a', 'b', 'c', 'd': // ERROR "duplicate case 'b' .value 98." 92 case x, x: // ERROR "duplicate case x .value 10." 93 } 94 } 95
