Initial commit: Go 1.23 release state

test/interface/convert.go

@@ -0,0 +1,146 @@
+// run
+
+// Copyright 2009 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.
+
+// Test all the different interface conversion runtime functions.
+
+package main
+
+type Stringer interface {
+	String() string
+}
+type StringLengther interface {
+	String() string
+	Length() int
+}
+type Empty interface{}
+
+type T string
+
+func (t T) String() string {
+	return string(t)
+}
+func (t T) Length() int {
+	return len(t)
+}
+
+type U string
+
+func (u U) String() string {
+	return string(u)
+}
+
+var t = T("hello")
+var u = U("goodbye")
+var e Empty
+var s Stringer = t
+var sl StringLengther = t
+var i int
+var ok bool
+
+func hello(s string) {
+	if s != "hello" {
+		println("not hello: ", s)
+		panic("fail")
+	}
+}
+
+func five(i int) {
+	if i != 5 {
+		println("not 5: ", i)
+		panic("fail")
+	}
+}
+
+func true(ok bool) {
+	if !ok {
+		panic("not true")
+	}
+}
+
+func false(ok bool) {
+	if ok {
+		panic("not false")
+	}
+}
+
+func main() {
+	// T2I
+	s = t
+	hello(s.String())
+
+	// I2T
+	t = s.(T)
+	hello(t.String())
+
+	// T2E
+	e = t
+
+	// E2T
+	t = e.(T)
+	hello(t.String())
+
+	// T2I again
+	sl = t
+	hello(sl.String())
+	five(sl.Length())
+
+	// I2I static
+	s = sl
+	hello(s.String())
+
+	// I2I dynamic
+	sl = s.(StringLengther)
+	hello(sl.String())
+	five(sl.Length())
+
+	// I2E (and E2T)
+	e = s
+	hello(e.(T).String())
+
+	// E2I
+	s = e.(Stringer)
+	hello(s.String())
+
+	// I2T2 true
+	t, ok = s.(T)
+	true(ok)
+	hello(t.String())
+
+	// I2T2 false
+	_, ok = s.(U)
+	false(ok)
+
+	// I2I2 true
+	sl, ok = s.(StringLengther)
+	true(ok)
+	hello(sl.String())
+	five(sl.Length())
+
+	// I2I2 false (and T2I)
+	s = u
+	sl, ok = s.(StringLengther)
+	false(ok)
+
+	// E2T2 true
+	t, ok = e.(T)
+	true(ok)
+	hello(t.String())
+
+	// E2T2 false
+	i, ok = e.(int)
+	false(ok)
+
+	// E2I2 true
+	sl, ok = e.(StringLengther)
+	true(ok)
+	hello(sl.String())
+	five(sl.Length())
+
+	// E2I2 false (and T2E)
+	e = u
+	sl, ok = e.(StringLengther)
+	false(ok)
+}