test: add more switch error handling tests

Some of these errors are reported in the wrong places.
That’s issue #15911 and #15912.

Change-Id: Ia09d7f89be4d15f05217a542a61b6ac08090dd87
Reviewed-on: https://go-review.googlesource.com/23588
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/test/switch5.go b/test/switch5.go
new file mode 100644 (file)
index 0000000..7da2c66
--- /dev/null
+++ b/test/switch5.go
@@ -0,0 +1,81 @@
+// 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
+
+import "fmt"
+
+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 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\(10\) in switch"
+       case float64(10):
+       case float64(10): // ERROR "duplicate case float64\(10\) in switch"
+       }
+}
+
+func f4(e interface{}) {
+       switch e.(type) {
+       case int:
+       case int: // ERROR "duplicate case int in type switch"
+       case int64:
+       case error: // ERROR "duplicate case error in type switch"
+       case error:
+       case fmt.Stringer:
+       case fmt.Stringer: // ERROR "duplicate case fmt.Stringer in type switch"
+       case struct {
+               i int "tag1"
+       }:
+       case struct {
+               i int "tag2"
+       }:
+       case struct {
+               i int "tag1"
+       }: // ERROR "duplicate case struct { i int .tag1. } in type switch"
+       }
+}
+
+func f5(a [1]int) {
+       switch a {
+       case [1]int{0}:
+       case [1]int{0}: // OK -- see issue 15896
+       }
+}

diff --git a/test/switch6.go b/test/switch6.go
new file mode 100644 (file)
index 0000000..bd62c62
--- /dev/null
+++ b/test/switch6.go
@@ -0,0 +1,32 @@
+// 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.
+
+// Check the compiler's switch handling that happens
+// at typechecking time.
+// This must be separate from other checks,
+// because errors during typechecking
+// prevent other errors from being discovered.
+
+package main
+
+// Verify that type switch statements with impossible cases are detected by the compiler.
+func f0(e error) {
+       switch e.(type) {
+       case int: // ERROR "impossible type switch case: e \(type error\) cannot have dynamic type int \(missing Error method\)"
+       }
+}
+
+// Verify that the compiler rejects multiple default cases.
+func f1(e interface{}) {
+       switch e { // ERROR "multiple defaults in switch"
+       default:
+       default:
+       }
+       switch e.(type) { // ERROR "multiple defaults in switch"
+       default:
+       default:
+       }
+}