cmd/gc: don't attempt to generate wrappers for blank interface methods
Fixes #5691.
R=golang-dev, bradfitz, daniel.morsing, rsc
CC=golang-dev
https://golang.org/cl/10255047
diff --git a/test/interface/explicit.go b/test/interface/explicit.go
index eb81156..36fa1a4 100644
--- a/test/interface/explicit.go
+++ b/test/interface/explicit.go
@@ -80,3 +80,22 @@
var m3 = M(ii) // ERROR "invalid|missing"
var m4 = M(jj) // ERROR "invalid|wrong type for M method"
+
+
+type B1 interface {
+ _()
+}
+
+type B2 interface {
+ M()
+ _()
+}
+
+type T2 struct{}
+
+func (t *T2) M() {}
+func (t *T2) _() {}
+
+// Check that nothing satisfies an interface with blank methods.
+var b1 B1 = &T2{} // ERROR "incompatible|missing _ method"
+var b2 B2 = &T2{} // ERROR "incompatible|missing _ method"
