Initial commit: Go 1.23 release state

test/typeswitch3.go

@@ -0,0 +1,56 @@
+// 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()
+}
+
+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"
+	}
+}