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>

1 files changed, 32 insertions, 0 deletions

diff --git a/test/switch6.go b/test/switch6.go
new file mode 100644
index 0000000000..bd62c620b6
--- /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:
+	}
+}