PR debug/29436, c/32326

PR debug/29436, c/32326
        * tree.c (build_type_attribute_qual_variant): Refuse to make
        a distinct copy of a struct/enum type.  Use build_distinct_type_copy.
        * doc/extend.texi (Type Attributes): Don't encourage people to add
        attributes to struct/enum types in a typedef.  Fix
        transparent_union example.

        * tree-inline.c (remap_type_1): Remove code that's redundant with
        remap_type.
        (build_duplicate_type): Set id.copy_decl.
        * c-common.c (handle_transparent_union_attribute): Simplify logic.

From-SVN: r130297

gcc/ChangeLog

@@ -1,3 +1,17 @@
+2007-11-19  Jason Merrill  <jason@redhat.com>
+
+	PR debug/29436, c/32326
+	* tree.c (build_type_attribute_qual_variant): Refuse to make
+	a distinct copy of a struct/enum type.  Use build_distinct_type_copy.
+	* doc/extend.texi (Type Attributes): Don't encourage people to add
+	attributes to struct/enum types in a typedef.  Fix
+	transparent_union example.
+
+	* tree-inline.c (remap_type_1): Remove code that's redundant with
+	remap_type.
+	(build_duplicate_type): Set id.copy_decl.
+	* c-common.c (handle_transparent_union_attribute): Simplify logic.
+
 2007-11-19  Peter Bergner  <bergner@vnet.ibm.com>
 
 	* config/rs6000/rs6000.c (invalid_e500_subreg,

gcc/c-common.c

@@ -5007,21 +5007,13 @@ handle_transparent_union_attribute (tree *node, tree name,
 				    tree ARG_UNUSED (args), int flags,
 				    bool *no_add_attrs)
 {
-  tree type = NULL;
+  tree type;
 
   *no_add_attrs = true;
 
-  if (DECL_P (*node))
-    {
-      if (TREE_CODE (*node) != TYPE_DECL)
-	goto ignored;
-      node = &TREE_TYPE (*node);
-      type = *node;
-    }
-  else if (TYPE_P (*node))
-    type = *node;
-  else
-    goto ignored;
+  if (TREE_CODE (*node) == TYPE_DECL)
+    node = &TREE_TYPE (*node);
+  type = *node;
 
   if (TREE_CODE (type) == UNION_TYPE)
     {

gcc/doc/extend.texi

@@ -3938,8 +3938,9 @@ attributes in header files without being concerned about a possible
 macro of the same name.  For example, you may use @code{__aligned__}
 instead of @code{aligned}.
 
-You may specify type attributes either in a @code{typedef} declaration
-or in an enum, struct or union type declaration or definition.
+You may specify type attributes in an enum, struct or union type
+declaration or definition, or for other types in a @code{typedef}
+declaration.
 
 For an enum, struct or union type, you may specify attributes either
 between the enum, struct or union tag and the name of the type, or
@@ -4098,11 +4099,11 @@ less useful.  Instead, @code{<sys/wait.h>} might define the interface
 as follows:
 
 @smallexample
-typedef union
+typedef union __attribute__ ((__transparent_union__))
   @{
     int *__ip;
     union wait *__up;
-  @} wait_status_ptr_t __attribute__ ((__transparent_union__));
+  @} wait_status_ptr_t;
 
 pid_t wait (wait_status_ptr_t);
 @end smallexample

gcc/testsuite/gcc.c-torture/execute/mayalias-2.c

@@ -1,5 +1,4 @@
-struct S { short x; };
-typedef struct S __attribute__((__may_alias__)) test;
+typedef struct __attribute__((__may_alias__)) { short x; } test;
 
 int f() {
   int a=10;

gcc/testsuite/gcc.c-torture/execute/mayalias-3.c

@@ -1,5 +1,4 @@
-struct S { short x; };
-typedef struct S __attribute__((__may_alias__)) test;
+typedef struct __attribute__((__may_alias__)) { short x; } test;
 
 test *p;
 

gcc/tree-inline.c

@@ -273,24 +273,8 @@ remap_decl (tree decl, copy_body_data *id)
 static tree
 remap_type_1 (tree type, copy_body_data *id)
 {
-  tree *node;
   tree new, t;
 
-  if (type == NULL)
-    return type;
-
-  /* See if we have remapped this type.  */
-  node = (tree *) pointer_map_contains (id->decl_map, type);
-  if (node)
-    return *node;
-
-  /* The type only needs remapping if it's variably modified.  */
-  if (! variably_modified_type_p (type, id->src_fn))
-    {
-      insert_decl_map (id, type, type);
-      return type;
-    }
-
   /* We do need a copy.  build and register it now.  If this is a pointer or
      reference type, remap the designated type and make a new pointer or
      reference type.  */
@@ -3593,6 +3577,7 @@ build_duplicate_type (tree type)
   id.dst_fn = current_function_decl;
   id.src_cfun = cfun;
   id.decl_map = pointer_map_create ();
+  id.copy_decl = copy_decl_no_change;
 
   type = remap_type_1 (type, &id);
 

gcc/tree.c

@@ -3666,15 +3666,26 @@ build_type_attribute_qual_variant (tree ttype, tree attribute, int quals)
       tree ntype;
       enum tree_code code = TREE_CODE (ttype);
 
-      ntype = copy_node (ttype);
+      /* Building a distinct copy of a tagged type is inappropriate; it
+	 causes breakage in code that expects there to be a one-to-one
+	 relationship between a struct and its fields.
+	 build_duplicate_type is another solution (as used in
+	 handle_transparent_union_attribute), but that doesn't play well
+	 with the stronger C++ type identity model.  */
+      if (TREE_CODE (ttype) == RECORD_TYPE
+	  || TREE_CODE (ttype) == UNION_TYPE
+	  || TREE_CODE (ttype) == QUAL_UNION_TYPE
+	  || TREE_CODE (ttype) == ENUMERAL_TYPE)
+	{
+	  warning (OPT_Wattributes,
+		   "ignoring attributes applied to %qT after definition",
+		   TYPE_MAIN_VARIANT (ttype));
+	  return build_qualified_type (ttype, quals);
+	}
+
+      ntype = build_distinct_type_copy (ttype);
 
-      TYPE_POINTER_TO (ntype) = 0;
-      TYPE_REFERENCE_TO (ntype) = 0;
       TYPE_ATTRIBUTES (ntype) = attribute;
-
-      /* Create a new main variant of TYPE.  */
-      TYPE_MAIN_VARIANT (ntype) = ntype;
-      TYPE_NEXT_VARIANT (ntype) = 0;
       set_type_quals (ntype, TYPE_UNQUALIFIED);
 
       hashcode = iterative_hash_object (code, hashcode);