From patchwork Thu May 26 18:30:40 2011
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Subject: [C++] PR 42056
From: Paolo Carlini <paolo.carlini@oracle.com>
X-Patchwork-Id: 97609
Message-Id: <4DDE9C50.7050601@oracle.com>
To: "gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>
Cc: Jason Merrill <jason@redhat.com>
Date: Thu, 26 May 2011 20:30:40 +0200

Hi,

I have just regtested on x86_64-linux the below patchlet for a simple 
accepts-invalid, exploiting type_uses_auto, as suggested by Jason.

We want to do that only when processing a template, because otherwise we 
get a duplicate diagnostic, see, eg, auto9.C; also, not returning 
error_mark_node unconditionally, means a better diagnostic, without 
redundant "array bound is not an integer constant before...". As for the 
error message itself, I'm just emitting what we otherwise emit outside 
templates...

Ok?

Thanks,
Paolo.

///////////////////
/cp
2011-05-26  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/42056
	* typeck2.c (build_functional_cast): When processing_template_decl,
	check for invalid uses of 'auto'.

/testsuite
2011-05-26  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/42056
	* testsuite/g++.dg/cpp0x/auto25.C: New.
	* testsuite/g++.dg/cpp0x/auto26.C: Likewise.

Index: testsuite/g++.dg/cpp0x/auto25.C
===================================================================
--- testsuite/g++.dg/cpp0x/auto25.C	(revision 0)
+++ testsuite/g++.dg/cpp0x/auto25.C	(revision 0)
@@ -0,0 +1,7 @@
+// PR c++/42056
+// { dg-options -std=c++0x }
+
+template<int> struct A
+{
+  int a[auto(1)]; // { dg-error "invalid use of" }
+};
Index: testsuite/g++.dg/cpp0x/auto26.C
===================================================================
--- testsuite/g++.dg/cpp0x/auto26.C	(revision 0)
+++ testsuite/g++.dg/cpp0x/auto26.C	(revision 0)
@@ -0,0 +1,7 @@
+// PR c++/42056
+// { dg-options -std=c++0x }
+
+template<int> void foo()
+{
+  int a[auto(1)]; // { dg-error "invalid use of" }
+}
Index: cp/typeck2.c
===================================================================
--- cp/typeck2.c	(revision 174301)
+++ cp/typeck2.c	(working copy)
@@ -1603,6 +1603,14 @@ build_functional_cast (tree exp, tree parms, tsubs
     {
       tree t;
 
+      if (type_uses_auto (type))
+	{
+	  if (complain & tf_error)
+	    error ("invalid use of %<auto%>");
+	  else
+	    return error_mark_node;
+	}
+
       /* Diagnose this even in a template.  We could also try harder
 	 to give all the usual errors when the type and args are
 	 non-dependent...  */