From patchwork Wed Oct 24 19:48:20 2012
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Subject: [C++] PR 53761
Date: Wed, 24 Oct 2012 09:48:20 -0000
From: Paolo Carlini <paolo.carlini@oracle.com>
X-Patchwork-Id: 193940
Message-Id: <50884604.2030308@oracle.com>
To: Jason Merrill <jason@redhat.com>
Cc: "gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>

Hi,

On 10/24/2012 06:57 PM, Jason Merrill wrote:
> On 10/10/2012 11:13 AM, Paolo Carlini wrote:
>> -      error ("type transparent class %qT does not have any fields", t);
>> +      if (TREE_CODE (t) == UNION_TYPE)
>> +        error ("type transparent union %qT does not have any 
>> fields", t);
>> +      else
>> +        error ("type transparent class %qT does not have any 
>> fields", t);
> If you use %q#T you don't need to repeat the class-key.
Indeed.
>
>> +        error ("type transparent union %qT cannot be made 
>> transparent", t);
>
> Let's say why not.
Thus I tested the below.

Thanks,
Paolo.

//////////////////////


Index: cp/class.c
===================================================================
--- cp/class.c	(revision 192762)
+++ cp/class.c	(working copy)
@@ -6261,7 +6261,7 @@ finish_struct_1 (tree t)
       tree field = first_field (t);
       if (field == NULL_TREE || error_operand_p (field))
 	{
-	  error ("type transparent class %qT does not have any fields", t);
+	  error ("type transparent %q#T does not have any fields", t);
 	  TYPE_TRANSPARENT_AGGR (t) = 0;
 	}
       else if (DECL_ARTIFICIAL (field))
@@ -6275,6 +6275,12 @@ finish_struct_1 (tree t)
 	    }
 	  TYPE_TRANSPARENT_AGGR (t) = 0;
 	}
+      else if (TYPE_MODE (t) != DECL_MODE (field))
+	{
+	  error ("type transparent %q#T cannot be made transparent because "
+		 "a field has neither pointer nor integer type", t);
+	  TYPE_TRANSPARENT_AGGR (t) = 0;
+	}
     }
 }
 
Index: testsuite/g++.dg/ext/transparent-union.C
===================================================================
--- testsuite/g++.dg/ext/transparent-union.C	(revision 0)
+++ testsuite/g++.dg/ext/transparent-union.C	(working copy)
@@ -0,0 +1,5 @@
+// PR c++/53761
+
+typedef union {    // { dg-error "type transparent" }
+   double x;
+} __attribute__(( __transparent_union__ )) example_t;