-// errchk $G -e $D/$F.go
+// errorcheck
// Copyright 2011 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 erroneous type switches are caught by the compiler.
+// Issue 2700, among other things.
+// Does not compile.
+
package main
+import (
+ "io"
+)
type I interface {
- M()
+ M()
}
-func main(){
- var x I
- switch x.(type) {
- case string: // ERROR "impossible"
- println("FAIL")
- }
+func main() {
+ var x I
+ switch x.(type) {
+ case string: // ERROR "impossible"
+ println("FAIL")
+ }
+
+ // Issue 2700: if the case type is an interface, nothing is impossible
+
+ var r io.Reader
+
+ _, _ = r.(io.Writer)
+
+ switch r.(type) {
+ case io.Writer:
+ }
+
+ // Issue 2827.
+ switch _ := r.(type) { // ERROR "invalid variable name _|no new variables?"
+ }
+}
+
+func noninterface() {
+ var i int
+ switch i.(type) { // ERROR "cannot type switch on non-interface value|not an interface"
+ case string:
+ case int:
+ }
+
+ type S struct {
+ name string
+ }
+ var s S
+ switch s.(type) { // ERROR "cannot type switch on non-interface value|not an interface"
+ }
}