test: add "duplicate" struct map key test

Update #4555.

R=gri, iant
CC=golang-dev
https://golang.org/cl/6944059

diff --git a/test/initializerr.go b/test/initializerr.go
index 48908c347864084ba64fad28299ac1fee57ebf6c..ca05414554d3480cabe1ce6a52207e8f72390644 100644 (file)
--- a/test/initializerr.go
+++ b/test/initializerr.go
@@ -26,3 +26,15 @@ var a5 = []byte { x: 2 }     // ERROR "index"
 
 var ok1 = S { }        // should be ok
 var ok2 = T { S: ok1 } // should be ok
+
+// These keys can be computed at compile time but they are
+// not constants as defined by the spec, so they do not trigger
+// compile-time errors about duplicate key values.
+// See issue 4555.
+
+type Key struct {X, Y int}
+
+var _ = map[Key]string{
+       Key{1,2}: "hello",
+       Key{1,2}: "world",
+}