gc: more cleanup

 * disallow surrogate pair runes.
 * diagnose impossible type assertions
 * eliminate another static buffer.
 * do not overflow lexbuf.
 * add -u flag to disable package unsafe.

R=ken2
CC=golang-dev
http://codereview.appspot.com/1619042

1 files changed, 20 insertions, 1 deletions

diff --git a/test/interface/explicit.go b/test/interface/explicit.go
index 797cec80e..120135cb6 100644
--- a/test/interface/explicit.go
+++ b/test/interface/explicit.go
@@ -1,4 +1,4 @@
-// errchk $G $D/$F.go
+// 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
@@ -50,3 +50,22 @@ func main() {
 	e = E(t) // ok
 	t = T(e) // ERROR "need explicit|need type assertion|incompatible"
 }
+
+type M interface { M() }
+var m M
+
+var _ = m.(int)	// ERROR "impossible type assertion"
+
+type Int int
+func (Int) M(float) {}
+
+var _ = m.(Int)	// ERROR "impossible type assertion"
+
+var ii int
+var jj Int
+
+var m1 M = ii	// ERROR "missing"
+var m2 M = jj	// ERROR "wrong type for M method"
+
+var m3 = M(ii)	// ERROR "missing"
+var m4 = M(jj)	// ERROR "wrong type for M method"