From patchwork Wed Dec 12 23:29:12 2012
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Subject: libgo patch committed: Delete from a nil map is now a no-op
Date: Wed, 12 Dec 2012 13:29:12 -0000
From: Ian Taylor <iant@google.com>
X-Patchwork-Id: 205687
Message-Id: <mcrvcc6df3r.fsf@google.com>
To: gcc-patches@gcc.gnu.org, gofrontend-dev@googlegroups.com

The Go spec was changed slightly: calling delete on a nil map is now a
no-op, rather than causing a runtime panic.  This patch implements that
in gccgo.  Bootstrapped and ran Go testsuite on
x86_64-unknown-linux-gnu.  Committed to mainline.

Ian


Index: libgo/runtime/go-map-delete.c
===================================================================
--- libgo/runtime/go-map-delete.c	(revision 194274)
+++ libgo/runtime/go-map-delete.c	(working copy)
@@ -27,7 +27,7 @@ __go_map_delete (struct __go_map *map, c
   void **pentry;
 
   if (map == NULL)
-    runtime_panicstring ("deletion of entry in nil map");
+    return;
 
   descriptor = map->__descriptor;
 
Index: gcc/testsuite/go.test/test/nil.go
===================================================================
--- gcc/testsuite/go.test/test/nil.go	(revision 193595)
+++ gcc/testsuite/go.test/test/nil.go	(working copy)
@@ -151,9 +151,8 @@ func maptest() {
 	shouldPanic(func() {
 		m[2] = 3
 	})
-	shouldPanic(func() {
-		delete(m, 2)
-	})
+	// can delete (non-existent) entries
+	delete(m, 2)
 }
 
 // nil slice