From patchwork Wed Apr 27 05:15:10 2011
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Subject: C++ PATCH for c++/42687 (arg-dependent lookup regression)
Date: Tue, 26 Apr 2011 19:15:10 -0000
From: Jason Merrill <jason@redhat.com>
X-Patchwork-Id: 92982
Message-Id: <4DB7A65E.5000706@redhat.com>
To: gcc-patches List <gcc-patches@gcc.gnu.org>

When we fixed using explicit scope to suppress virtual calling, it broke 
using parentheses to suppress argument-dependent lookup.  Fixed thus.

Tested x86_64-pc-linux-gnu, applied to trunk, 4.4, 4.5 and 4.6.
commit 2bc3ed125eab1075ea18c7c80e5ab908130861fd
Author: Jason Merrill <jason@redhat.com>
Date:   Tue Apr 26 21:39:34 2011 -0400

    	PR c++/42687
    	* parser.c (cp_parser_primary_expression): Set *idk to
    	CP_ID_KIND_NONE for a parenthesized identifier.


diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 6da285e..68ce052 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -3437,6 +3437,12 @@ cp_parser_primary_expression (cp_parser *parser,
 	       `&A::B' might be a pointer-to-member, but `&(A::B)' is
 	       not.  */
 	    finish_parenthesized_expr (expr);
+	    /* DR 705: Wrapping an unqualified name in parentheses
+	       suppresses arg-dependent lookup.  We want to pass back
+	       CP_ID_KIND_QUALIFIED for suppressing vtable lookup
+	       (c++/37862), but none of the others.  */
+	    if (*idk != CP_ID_KIND_QUALIFIED)
+	      *idk = CP_ID_KIND_NONE;
 	  }
 	/* The `>' token might be the end of a template-id or
 	   template-parameter-list now.  */
diff --git a/gcc/testsuite/g++.dg/lookup/koenig13.C b/gcc/testsuite/g++.dg/lookup/koenig13.C
new file mode 100644
index 0000000..625a181
--- /dev/null
+++ b/gcc/testsuite/g++.dg/lookup/koenig13.C
@@ -0,0 +1,16 @@
+// PR c++/42687
+// DR 705
+
+namespace N
+{
+    struct S { };
+    void f(const S &) { }
+}
+
+void f(const N::S &) { }
+
+int main()
+{
+    N::S v;
+    (f)(v); // no ambiguity: ADL is prevented with (), only ::f is considered
+}