diff mbox series

[C++/84812] ICE with local fn decl

Message ID 1a63cb7f-5c42-8b59-f88a-3b410180f4e1@acm.org
State New
Headers show
Series [C++/84812] ICE with local fn decl | expand

Commit Message

Nathan Sidwell March 19, 2018, 2:04 p.m. UTC 
This bug happens when the machinery to check for an implicit extern "C" 
linkage on a local declaration, meets an ambiguous local lookup.  I was 
misled by a comment that implied TREE_LIST -> overload.  That was true 
way back, but now means ambiguous lookup.

I declined the opportunity to micro-optimize the test to 'TREE_CODE (x) 
== ERROR_MARK || TTEE_CODE (X) == TREE_LIST'.

nathan
diff mbox series

Patch

2018-03-19  Nathan Sidwell  <nathan@acm.org>

	PR c++/84812
	* name-lookup.c (set_local_extern_decl_linkage): Defend against
	ambiguous lookups.

	PR c++/84812
	* g++.dg/lookup/pr84812.C: New.

Index: cp/name-lookup.c
===================================================================
--- cp/name-lookup.c	(revision 258642)
+++ cp/name-lookup.c	(working copy)
@@ -2878,7 +2878,9 @@  set_local_extern_decl_linkage (tree decl
 	    = find_namespace_value (current_namespace, DECL_NAME (decl));
 	  loc_value = ns_value;
 	}
-      if (loc_value == error_mark_node)
+      if (loc_value == error_mark_node
+	  /* An ambiguous lookup.  */
+	  || (loc_value && TREE_CODE (loc_value) == TREE_LIST))
 	loc_value = NULL_TREE;
 
       for (ovl_iterator iter (loc_value); iter; ++iter)
@@ -2926,7 +2928,8 @@  set_local_extern_decl_linkage (tree decl
       if (ns_value == decl)
 	ns_value = find_namespace_value (current_namespace, DECL_NAME (decl));
 
-      if (ns_value == error_mark_node)
+      if (ns_value == error_mark_node
+	  || (ns_value && TREE_CODE (ns_value) == TREE_LIST))
 	ns_value = NULL_TREE;
 
       for (ovl_iterator iter (ns_value); iter; ++iter)
Index: testsuite/g++.dg/lookup/pr84812.C
===================================================================
--- testsuite/g++.dg/lookup/pr84812.C	(revision 0)
+++ testsuite/g++.dg/lookup/pr84812.C	(working copy)
@@ -0,0 +1,18 @@ 
+// PR 84812.  ICE determining implicit "C" linkage
+
+struct A { void foo(); };
+struct B { void foo(); };
+
+struct C : A, B
+{
+  void X ();
+};
+
+void C::X ()
+{
+  void foo (); // local decl of ::foo
+
+  foo ();
+}
+
+// { dg-final { scan-assembler "_Z3foov" } }