* decl.c (duplicate_decls): Don't try to unify an implicit typedef

	with an explicit one.
	(follow_tag_typedef): New.
	(lookup_tag): Use it to extract the tag of an explicit typedef.
	(xref_tag): Likewise.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@52213 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 439a3fc..a9b70e9 100644 (file)
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,11 @@
+2002-04-12  Richard Sandiford  <rsandifo@redhat.com>
+
+       * decl.c (duplicate_decls): Don't try to unify an implicit typedef
+       with an explicit one.
+       (follow_tag_typedef): New.
+       (lookup_tag): Use it to extract the tag of an explicit typedef.
+       (xref_tag): Likewise.
+
 2002-04-11  Andrew Haley  <aph@redhat.com>
 
        * typeck.c (type_after_usual_arithmetic_conversions):

diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index dc9d373..93e6305 100644 (file)
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -82,6 +82,7 @@ static tree grokfndecl PARAMS ((tree, tree, tree, tree, int,
                              enum overload_flags, tree,
                              tree, int, int, int, int, int, int, tree));
 static tree grokvardecl PARAMS ((tree, tree, RID_BIT_TYPE *, int, int, tree));
+static tree follow_tag_typedef PARAMS ((tree));
 static tree lookup_tag PARAMS ((enum tree_code, tree,
                              struct binding_level *, int));
 static void set_identifier_type_value_with_scope
@@ -3426,6 +3427,18 @@ duplicate_decls (newdecl, olddecl)
        }
     }
 
+  /* Do not merge an implicit typedef with an explicit one.  In:
+
+       class A;
+       ...
+       typedef class A A __attribute__ ((foo));
+
+     the attribute should apply only to the typedef.  */
+  if (TREE_CODE (olddecl) == TYPE_DECL
+      && (DECL_IMPLICIT_TYPEDEF_P (olddecl)
+         || DECL_IMPLICIT_TYPEDEF_P (newdecl)))
+    return 0;
+
   /* If new decl is `static' and an `extern' was seen previously,
      warn about it.  */
   warn_extern_redeclared_static (newdecl, olddecl);
@@ -5285,6 +5298,45 @@ storetags (tags)
   current_binding_level->tags = tags;
 }
 \f
+/* Return the type that should be used when TYPE's name is preceded
+   by a tag such as 'struct' or 'union', or null if the name cannot
+   be used in this way.
+
+   For example, when processing the third line of:
+
+       struct A;
+       typedef struct A A;
+       struct A;
+
+   lookup of A will find the typedef.  Given A's typedef, this function
+   will return the type associated with "struct A".  For the tag to be
+   anything other than TYPE, TYPE must be a typedef whose original type
+   has the same name and context as TYPE itself.
+
+   It is not valid for a typedef of an anonymous type to be used with
+   an explicit tag:
+
+       typedef struct { ... } B;
+       struct B;
+
+   Return null for this case.  */
+
+static tree
+follow_tag_typedef (type)
+     tree type;
+{
+  tree original;
+
+  original = original_type (type);
+  if (TYPE_IDENTIFIER (original) == TYPE_IDENTIFIER (type)
+      && (CP_DECL_CONTEXT (TYPE_NAME (original))
+         == CP_DECL_CONTEXT (TYPE_NAME (type)))
+      && !(CLASS_TYPE_P (original) && TYPE_WAS_ANONYMOUS (original)))
+    return original;
+  else
+    return NULL_TREE;
+}
+
 /* Given NAME, an IDENTIFIER_NODE,
    return the structure (or union or enum) definition for that name.
    Searches binding levels from BINDING_LEVEL up to the global level.
@@ -5336,18 +5388,23 @@ lookup_tag (form, name, binding_level, thislevel_only)
            else
              old = BINDING_TYPE (old);
 
-           /* If it has an original type, it is a typedef, and we
-              should not return it.  */
-           if (old && DECL_ORIGINAL_TYPE (TYPE_NAME (old)))
-             old = NULL_TREE;
-           if (old && TREE_CODE (old) != form
-               && (form == ENUMERAL_TYPE || TREE_CODE (old) == ENUMERAL_TYPE))
+           if (old)
              {
-               error ("`%#D' redeclared as %C", old, form);
-               return NULL_TREE;
+               /* We've found something at this binding level.  If it is
+                  a typedef, extract the tag it refers to.  Lookup fails
+                  if the typedef doesn't refer to a taggable type.  */
+               old = follow_tag_typedef (old);
+               if (!old)
+                 return NULL_TREE;
+               if (TREE_CODE (old) != form
+                   && (form == ENUMERAL_TYPE
+                       || TREE_CODE (old) == ENUMERAL_TYPE))
+                 {
+                   error ("`%#D' redeclared as %C", old, form);
+                   return NULL_TREE;
+                 }
+               return old;
              }
-           if (old)
-             return old;
            if (thislevel_only || tail == global_namespace)
              return NULL_TREE;
          }
@@ -12685,7 +12742,6 @@ xref_tag (code_type_node, name, globalize)
   enum tree_code code;
   register tree ref, t;
   struct binding_level *b = current_binding_level;
-  int got_type = 0;
   tree attributes = NULL_TREE;
   tree context = NULL_TREE;
 
@@ -12722,7 +12778,6 @@ xref_tag (code_type_node, name, globalize)
     {
       t = name;
       name = TYPE_IDENTIFIER (t);
-      got_type = 1;
     }
   else
     t = IDENTIFIER_TYPE_VALUE (name);
@@ -12767,18 +12822,20 @@ xref_tag (code_type_node, name, globalize)
     {
       if (t)
        {
+         ref = follow_tag_typedef (t);
+
          /* [dcl.type.elab] If the identifier resolves to a
             typedef-name or a template type-parameter, the
             elaborated-type-specifier is ill-formed.  */
-         if (t != TYPE_MAIN_VARIANT (t)
-             || (CLASS_TYPE_P (t) && TYPE_WAS_ANONYMOUS (t)))
-           pedwarn ("using typedef-name `%D' after `%s'",
-                       TYPE_NAME (t), tag_name (tag_code));
+         if (!ref)
+           {
+             pedwarn ("using typedef-name `%D' after `%s'",
+                      TYPE_NAME (t), tag_name (tag_code));
+             ref = t;
+           }
          else if (TREE_CODE (t) == TEMPLATE_TYPE_PARM)
            error ("using template type parameter `%T' after `%s'",
-                     t, tag_name (tag_code));
-
-         ref = t;
+                  t, tag_name (tag_code));
        }
       else
        ref = lookup_tag (code, name, b, 0);