// 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.)?" } }