c-tree.h: Delete COMPARE_DIFFERENT_TU from enumeration.

	* c-tree.h: Delete COMPARE_DIFFERENT_TU from enumeration.
	* c-typeck.c (same_translation_unit_p): New function.
	(comptypes): Use it instead of flags parameter to identify
	structure types from different translation units.
	* c-decl.c (duplicate_decls): Always call comptypes with
	COMPTYPE_STRICT flags argument.
	(c_reset_state): Set BLOCK_SUPERCONTEXT of the block formed
	to file_scope_decl.

From-SVN: r70953

gcc/ChangeLog

 2003-08-30  Zack Weinberg  <zack@codesourcery.com>
 
+	* c-tree.h: Delete COMPARE_DIFFERENT_TU from enumeration.
+	* c-typeck.c (same_translation_unit_p): New function.
+	(comptypes): Use it instead of flags parameter to identify
+	structure types from different translation units.
+	* c-decl.c (duplicate_decls): Always call comptypes with
+	COMPTYPE_STRICT flags argument.
+	(c_reset_state): Set BLOCK_SUPERCONTEXT of the block formed
+	to file_scope_decl.
+
+2003-08-30  Zack Weinberg  <zack@codesourcery.com>
+
 	* c-tree.h (C_TYPE_INCOMPLETE_VARS): New macro.
 	* c-decl.c (struct c_scope): Remove "incomplete" field.
 	(pushdecl): Attach variables with incomplete types to

gcc/c-decl.c

@@ -775,10 +775,8 @@ static int
 duplicate_decls (tree newdecl, tree olddecl, int different_binding_level,
 		 int different_tu)
 {
-  int comptype_flags = (different_tu ? COMPARE_DIFFERENT_TU
-			: COMPARE_STRICT);
   int types_match = comptypes (TREE_TYPE (newdecl), TREE_TYPE (olddecl),
-			       comptype_flags);
+			       COMPARE_STRICT);
   int new_is_definition = (TREE_CODE (newdecl) == FUNCTION_DECL
 			   && DECL_INITIAL (newdecl) != 0);
   tree oldtype = TREE_TYPE (olddecl);
@@ -897,7 +895,7 @@ duplicate_decls (tree newdecl, tree olddecl, int different_binding_level,
 
 	  if (trytype)
 	    {
-	      types_match = comptypes (newtype, trytype, comptype_flags);
+	      types_match = comptypes (newtype, trytype, COMPARE_STRICT);
 	      if (types_match)
 		oldtype = trytype;
 	      if (! different_binding_level)
@@ -983,7 +981,7 @@ duplicate_decls (tree newdecl, tree olddecl, int different_binding_level,
 		 && ! pedantic
 		 /* Return types must still match.  */
 		 && comptypes (TREE_TYPE (oldtype),
-			       TREE_TYPE (newtype), comptype_flags)
+			       TREE_TYPE (newtype), COMPARE_STRICT)
 		 && TYPE_ARG_TYPES (newtype) == 0))
     {
       error ("%Hconflicting types for '%D'",
@@ -992,7 +990,7 @@ duplicate_decls (tree newdecl, tree olddecl, int different_binding_level,
 	 involving an empty arglist vs a nonempty one.  */
       if (TREE_CODE (olddecl) == FUNCTION_DECL
 	  && comptypes (TREE_TYPE (oldtype),
-			TREE_TYPE (newtype), comptype_flags)
+			TREE_TYPE (newtype), COMPARE_STRICT)
 	  && ((TYPE_ARG_TYPES (oldtype) == 0
 	       && DECL_INITIAL (olddecl) == 0)
 	      ||
@@ -1135,7 +1133,7 @@ duplicate_decls (tree newdecl, tree olddecl, int different_binding_level,
 	      /* Type for passing arg must be consistent
 		 with that declared for the arg.  */
 	      if (! comptypes (TREE_VALUE (parm), TREE_VALUE (type),
-			       comptype_flags))
+			       COMPARE_STRICT))
 		{
                   const location_t *locus = &DECL_SOURCE_LOCATION (newdecl);
 		  error ("%Hprototype for '%D' follows and argument %d "
@@ -6701,6 +6699,7 @@ c_reset_state (void)
       current_scope = global_scope;
   file_scope_decl = current_file_decl;
   DECL_INITIAL (file_scope_decl) = poplevel (1, 0, 0);
+  BLOCK_SUPERCONTEXT (DECL_INITIAL (file_scope_decl)) = file_scope_decl;
   truly_local_externals = NULL_TREE;
 
   /* Start a new global binding level.  */

gcc/c-tree.h

@@ -244,8 +244,7 @@ extern bool c_warn_unused_global_decl (tree);
 
 /* For use with comptypes.  */
 enum {
-  COMPARE_STRICT = 0,
-  COMPARE_DIFFERENT_TU = 1
+  COMPARE_STRICT = 0
 };
 
 extern tree require_complete_type (tree);

gcc/c-typeck.c

@@ -50,6 +50,7 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 static int missing_braces_mentioned;
 
 static tree qualify_type (tree, tree);
+static int same_translation_unit_p (tree, tree);
 static int tagged_types_tu_compatible_p (tree, tree, int);
 static int comp_target_types (tree, tree, int);
 static int function_types_compatible_p (tree, tree, int);
@@ -564,7 +565,7 @@ comptypes (tree type1, tree type2, int flags)
 
     case ENUMERAL_TYPE:
     case UNION_TYPE:
-      if (val != 1 && (flags & COMPARE_DIFFERENT_TU))
+      if (val != 1 && !same_translation_unit_p (t1, t2))
 	val = tagged_types_tu_compatible_p (t1, t2, flags);
       break;
 
@@ -606,6 +607,34 @@ comp_target_types (tree ttl, tree ttr, int reflexive)
 
 /* Subroutines of `comptypes'.  */
 
+/* Determine whether two types derive from the same translation unit.
+   If the CONTEXT chain ends in a null, that type's context is still
+   being parsed, so if two types have context chains ending in null,
+   they're in the same translation unit.  */
+static int
+same_translation_unit_p (tree t1, tree t2)
+{
+  while (t1 && TREE_CODE (t1) != TRANSLATION_UNIT_DECL)
+    switch (TREE_CODE_CLASS (TREE_CODE (t1)))
+      {
+      case 'd': t1 = DECL_CONTEXT (t1); break;
+      case 't': t1 = TYPE_CONTEXT (t1); break;
+      case 'b': t1 = BLOCK_SUPERCONTEXT (t1); break;
+      default: abort ();
+      }
+
+  while (t2 && TREE_CODE (t2) != TRANSLATION_UNIT_DECL)
+    switch (TREE_CODE_CLASS (TREE_CODE (t2)))
+      {
+      case 'd': t2 = DECL_CONTEXT (t1); break;
+      case 't': t2 = TYPE_CONTEXT (t2); break;
+      case 'b': t2 = BLOCK_SUPERCONTEXT (t2); break;
+      default: abort ();
+      }
+
+  return t1 == t2;
+}
+
 /* The C standard says that two structures in different translation
    units are compatible with each other only if the types of their
    fields are compatible (among other things).  So, consider two copies