Patchwork C++ PATCH to warn about ignored attributes

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Submitter Jason Merrill
Date March 1, 2012, 5:51 p.m.
Message ID <4F4FB73C.9090704@redhat.com>
Download mbox | patch
Permalink /patch/144094/
State New
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Comments

Jason Merrill - March 1, 2012, 5:51 p.m.
On 02/14/2012 08:50 PM, Jason Merrill wrote:
> While looking at PR 51930, I discovered that we were silently ignoring
> attributes on explicit instantiations; this patch warns about this. This
> isn't exactly a regression, but the submitter ran into it as a result of
> a behavior change in 4.7, and the patch is extremely safe, so I think it
> should go in.

It turns out that we already had a warning for this situation that also 
gives a suggestion for how to deal with it, so I'm going to make that 
warning apply to this case as well.

Tested x86_64-pc-linux-gnu, applying to trunk.

Patch

commit fc93bb109ba5d22a5c08ee026d572436a999bdef
Author: Jason Merrill <jason@redhat.com>
Date:   Wed Feb 29 21:51:33 2012 -0500

    	PR c++/51930
    	* decl.c (check_tag_decl): Move warning for misplaced attributes here.
    	(shadow_tag): From here.
    	* parser.c (cp_parser_explicit_instantiation): Don't warn here.

diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 2a6a516..c47f87c 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -4216,6 +4216,19 @@  check_tag_decl (cp_decl_specifier_seq *declspecs)
         error ("%<constexpr%> cannot be used for type declarations");
     }
 
+  if (declspecs->attributes)
+    {
+      location_t loc = input_location;
+      if (!CLASSTYPE_TEMPLATE_INSTANTIATION (declared_type))
+	/* For a non-template class, use the name location; for a template
+	   class (an explicit instantiation), use the current location.  */
+	input_location = location_of (declared_type);
+      warning (0, "attribute ignored in declaration of %q#T", declared_type);
+      warning (0, "attribute for %q#T must follow the %qs keyword",
+	       declared_type, class_key_or_enum_as_string (declared_type));
+      input_location = loc;
+    }
+
   return declared_type;
 }
 
@@ -4240,14 +4253,6 @@  shadow_tag (cp_decl_specifier_seq *declspecs)
   if (!t)
     return NULL_TREE;
 
-  if (declspecs->attributes)
-    {
-      warning (0, "attribute ignored in declaration of %q+#T", t);
-      warning (0, "attribute for %q+#T must follow the %qs keyword",
-	       t, class_key_or_enum_as_string (t));
-
-    }
-
   if (maybe_process_partial_specialization (t) == error_mark_node)
     return NULL_TREE;
 
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 3e2be97..491f48e 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -13122,9 +13122,6 @@  cp_parser_explicit_instantiation (cp_parser* parser)
       tree type;
 
       type = check_tag_decl (&decl_specifiers);
-      if (decl_specifiers.attributes)
-	warning (OPT_Wattributes,
-		 "attributes ignored on explicit type instantiation");
       /* Turn access control back on for names used during
 	 template instantiation.  */
       pop_deferring_access_checks ();
diff --git a/gcc/testsuite/g++.dg/ext/attrib43.C b/gcc/testsuite/g++.dg/ext/attrib43.C
index fe9f072..acae3f2 100644
--- a/gcc/testsuite/g++.dg/ext/attrib43.C
+++ b/gcc/testsuite/g++.dg/ext/attrib43.C
@@ -2,4 +2,4 @@  template <class T> struct A { };
 
 template
 __attribute__ ((packed))
-struct A<int>;			// { dg-warning "attributes ignored" }
+struct A<int>;			// { dg-warning "attribute" }