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
10package main
11
12func 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
24func 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
32func 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
41func 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
53func 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.
61func 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).
72func 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.
82func 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