1 files changed, 94 insertions, 0 deletions
diff --git a/test/switch5.go b/test/switch5.go
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+++ b/test/switch5.go
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+// 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."
+	}
+}