// errorcheck // Copyright 2016 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 switch statements with duplicate cases are detected by the compiler. // Does not compile. package main func f0(x int) { switch x { case 0: case 0: // ERROR "duplicate case 0 in switch" } switch x { case 0: case int(0): // ERROR "duplicate case int.0. .value 0. in switch" } } func f1(x float32) { switch x { case 5: case 5: // ERROR "duplicate case 5 in switch" case 5.0: // ERROR "duplicate case 5 in switch" } } func f2(s string) { switch s { case "": case "": // ERROR "duplicate case .. in switch" case "abc": case "abc": // ERROR "duplicate case .abc. in switch" } } func f3(e interface{}) { switch e { case 0: case 0: // ERROR "duplicate case 0 in switch" case int64(0): case float32(10): case float32(10): // ERROR "duplicate case float32\(10\) .value 10. in switch" case float64(10): case float64(10): // ERROR "duplicate case float64\(10\) .value 10. in switch" } } func f5(a [1]int) { switch a { case [1]int{0}: case [1]int{0}: // OK -- see issue 15896 } } // Ensure duplicate const bool clauses are accepted. func f6() int { switch { case 0 == 0: return 0 case 1 == 1: // Intentionally OK, even though a duplicate of the above const true return 1 } return 2 } // Ensure duplicates in ranges are detected (issue #17517). func f7(a int) { switch a { case 0: case 0, 1: // ERROR "duplicate case 0" case 1, 2, 3, 4: // ERROR "duplicate case 1" } } // Ensure duplicates with simple literals are printed as they were // written, not just their values. Particularly useful for runes. func f8(r rune) { const x = 10 switch r { case 33, 33: // ERROR "duplicate case 33 in switch" case 34, '"': // ERROR "duplicate case '"' .value 34. in switch" case 35, rune('#'): // ERROR "duplicate case rune.'#'. .value 35. in switch" case 36, rune(36): // ERROR "duplicate case rune.36. .value 36. in switch" case 37, '$'+1: // ERROR "duplicate case '\$' \+ 1 .value 37. in switch" case 'b': case 'a', 'b', 'c', 'd': // ERROR "duplicate case 'b' .value 98." case x, x: // ERROR "duplicate case x .value 10." } }