Imported Upstream version 60upstream/60

1 files changed, 75 insertions, 0 deletions

diff --git a/test/interface/explicit.go b/test/interface/explicit.go
new file mode 100644
index 000000000..daae59b36
--- /dev/null
+++ b/test/interface/explicit.go
@@ -0,0 +1,75 @@
+// errchk $G -e $D/$F.go
+
+// 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.
+
+// Static error messages about interface conversions.
+
+package main
+
+type T struct {
+	a int
+}
+
+var t *T
+
+type I interface {
+	M()
+}
+
+var i I
+
+type I2 interface {
+	M()
+	N()
+}
+
+var i2 I2
+
+type E interface{}
+
+var e E
+
+func main() {
+	e = t // ok
+	t = e // ERROR "need explicit|need type assertion"
+
+	// neither of these can work,
+	// because i has an extra method
+	// that t does not, so i cannot contain a t.
+	i = t // ERROR "incompatible|missing M method"
+	t = i // ERROR "incompatible|need type assertion"
+
+	i = i2 // ok
+	i2 = i // ERROR "incompatible|missing N method"
+
+	i = I(i2)  // ok
+	i2 = I2(i) // ERROR "invalid|missing N method"
+
+	e = E(t) // ok
+	t = T(e) // ERROR "need explicit|need type assertion|incompatible" "as type [*]T"
+}
+
+type M interface {
+	M()
+}
+
+var m M
+
+var _ = m.(int) // ERROR "impossible type assertion"
+
+type Int int
+
+func (Int) M(float64) {}
+
+var _ = m.(Int) // ERROR "impossible type assertion"
+
+var ii int
+var jj Int
+
+var m1 M = ii // ERROR "incompatible|missing"
+var m2 M = jj // ERROR "incompatible|wrong type for M method"
+
+var m3 = M(ii) // ERROR "invalid|missing"
+var m4 = M(jj) // ERROR "invalid|wrong type for M method"