cp-tree.h (PROCESSING_REAL_TEMPLATE_DECL_P): New macro.

1998-07-31  Mark Mitchell  <mark@markmitchell.com>
	* cp-tree.h (PROCESSING_REAL_TEMPLATE_DECL_P): New macro.
	(maybe_check_template_type): New function.
	* decl.c (maybe_process_template_type_declaration): New function,
	split out from pushtag  Call maybe_check_template_type.
	(pushtag): Use it.  Use PROCESSING_REAL_TEMPLATE_DECL_P.
	(xref_tag): Use PROCESSING_REAL_TEMPLATE_DECL_P.
	* friend.c (do_friend): Use PROCESSING_REAL_TEMPLATE_DECL_P.
	* pt.c (template_class_depth_real): Generalization of ...
	(template_class_depth): Use it.
	(register_specialization): Use duplicate_decls for duplicate
	declarations of specializations.
	(maybe_check_template_type): New function.
	(push_template_decl_real): Fix comment.
	(convert_nontype_argument): Likewise.
	(lookup_template_class): Likewise.  Avoid an infinite loop on
	erroneous code.
	(tsubst_friend_function): Fix comment.
	(tsubst, case FUNCTION_DECL): Deal with a DECL_TI_TEMPLATE that is
	an IDENTIFIER_NODE.
	* semantics.c (begin_function_definition): Use
	reset_specialization to note that template headers don't apply
	directly to declarations after the opening curly for a function.

From-SVN: r21505

11 files changed, 284 insertions, 88 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 69c8447..3feeaac 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,28 @@
+1998-07-31  Mark Mitchell  <mark@markmitchell.com>
+
+	* cp-tree.h (PROCESSING_REAL_TEMPLATE_DECL_P): New macro.
+	(maybe_check_template_type): New function.
+	* decl.c (maybe_process_template_type_declaration): New function,
+	split out from pushtag  Call maybe_check_template_type.
+	(pushtag): Use it.  Use PROCESSING_REAL_TEMPLATE_DECL_P.
+	(xref_tag): Use PROCESSING_REAL_TEMPLATE_DECL_P.
+	* friend.c (do_friend): Use PROCESSING_REAL_TEMPLATE_DECL_P.
+	* pt.c (template_class_depth_real): Generalization of ...
+	(template_class_depth): Use it.
+	(register_specialization): Use duplicate_decls for duplicate
+	declarations of specializations.
+	(maybe_check_template_type): New function.
+	(push_template_decl_real): Fix comment.
+	(convert_nontype_argument): Likewise.
+	(lookup_template_class): Likewise.  Avoid an infinite loop on
+	erroneous code.
+	(tsubst_friend_function): Fix comment.
+	(tsubst, case FUNCTION_DECL): Deal with a DECL_TI_TEMPLATE that is
+	an IDENTIFIER_NODE.
+	* semantics.c (begin_function_definition): Use
+	reset_specialization to note that template headers don't apply
+	directly to declarations after the opening curly for a function.
+
 1998-07-29  Jason Merrill  <jason@yorick.cygnus.com>
 
 	* decl.c (push_overloaded_decl): Use current_namespace instead of
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index be97c1b..4e1d1bd 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -1692,6 +1692,12 @@ extern int flag_new_for_scope;
 #define SET_CLASSTYPE_EXPLICIT_INSTANTIATION(NODE) \
   (CLASSTYPE_USE_TEMPLATE(NODE) = 3)
 
+/* Non-zero iff we are currently processing a declaration for an
+   entity with its own template parameter list, and which is not a
+   full specialization.  */
+#define PROCESSING_REAL_TEMPLATE_DECL_P() \
+  (processing_template_decl > template_class_depth (current_class_type))
+
 /* This function may be a guiding decl for a template.  */
 #define DECL_MAYBE_TEMPLATE(NODE) DECL_LANG_FLAG_4 (NODE)
 /* We know what we're doing with this decl now.  */
@@ -2794,6 +2800,7 @@ extern int template_class_depth                 PROTO((tree));
 extern int is_specialization_of                 PROTO((tree, tree));
 extern int comp_template_args                   PROTO((tree, tree));
 extern void maybe_process_partial_specialization PROTO((tree));
+extern void maybe_check_template_type           PROTO((tree));
 
 extern int processing_specialization;
 extern int processing_explicit_instantiation;
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 2558386..0b32a3d 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -176,6 +176,7 @@ static int member_function_or_else PROTO((tree, tree, char *));
 static void bad_specifiers PROTO((tree, char *, int, int, int, int,
 				  int));
 static void lang_print_error_function PROTO((char *));
+static tree maybe_process_template_type_declaration PROTO((tree, int, struct binding_level*));
 
 #if defined (DEBUG_CP_BINDING_LEVELS)
 static void indent PROTO((void));
@@ -2223,6 +2224,88 @@ pop_everything ()
 #endif
 }
 
+/* The type TYPE is being declared.  If it is a class template, or a
+   specialization of a class template, do any processing required and
+   perform error-checking.  If IS_FRIEND is non-zero, this TYPE is
+   being declared a friend.  B is the binding level at which this TYPE
+   should be bound.
+
+   Returns the TYPE_DECL for TYPE, which may have been altered by this
+   processing.  */
+
+static tree 
+maybe_process_template_type_declaration (type, globalize, b)
+     tree type;
+     int globalize;
+     struct binding_level* b;
+{
+  tree decl = TYPE_NAME (type);
+ 
+  if (processing_template_parmlist)
+    /* You can't declare a new template type in a template parameter
+       list.  But, you can declare a non-template type:
+       
+         template <class A*> struct S;
+       
+       is a forward-declaration of `A'.  */
+    ;
+  else 
+    {
+      maybe_check_template_type (type);
+
+      if (IS_AGGR_TYPE (type)
+	  && (/* If !GLOBALIZE then we are looking at a definition.
+		 It may not be a primary template.  (For example, in:
+		  
+		 template <class T>
+		 struct S1 { class S2 {}; }
+		  
+		 we have to push_template_decl for S2.)  */
+	      (processing_template_decl && !globalize)
+	      /* If we are declaring a friend template class, we will
+		 have GLOBALIZE set, since something like:
+
+		 template <class T>
+		 struct S1 {
+		   template <class U>
+		   friend class S2; 
+		 };
+
+		 declares S2 to be at global scope.  */
+	      || PROCESSING_REAL_TEMPLATE_DECL_P ()))
+	{
+	  /* This may change after the call to
+	     push_template_decl_real, but we want the original value.  */
+	  tree name = DECL_NAME (decl);
+
+	  decl = push_template_decl_real (decl, globalize);
+	  /* If the current binding level is the binding level for the
+	     template parameters (see the comment in
+	     begin_template_parm_list) and the enclosing level is a class
+	     scope, and we're not looking at a friend, push the
+	     declaration of the member class into the class scope.  In the
+	     friend case, push_template_decl will already have put the
+	     friend into global scope, if appropriate.  */
+	  if (!globalize && b->pseudo_global
+	      && b->level_chain->parm_flag == 2)
+	    {
+	      pushdecl_with_scope (CLASSTYPE_TI_TEMPLATE (type),
+				   b->level_chain);
+	      /* Put this tag on the list of tags for the class, since
+		 that won't happen below because B is not the class
+		 binding level, but is instead the pseudo-global level.  */
+	      b->level_chain->tags = 
+		saveable_tree_cons (name, type, b->level_chain->tags);
+	      TREE_NONLOCAL_FLAG (type) = 1;
+	      if (TYPE_SIZE (current_class_type) == NULL_TREE)
+		CLASSTYPE_TAGS (current_class_type) = b->level_chain->tags;
+	    }
+	}
+    }
+
+  return decl;
+}
+
 /* Push a tag name NAME for struct/class/union/enum type TYPE.
    Normally put it into the inner-most non-tag-transparent scope,
    but if GLOBALIZE is true, put it in the inner-most non-class scope.
@@ -2298,63 +2381,8 @@ pushtag (name, type, globalize)
 	  TYPE_NAME (type) = d;
 	  DECL_CONTEXT (d) = FROB_CONTEXT (context);
 
-	  if (processing_template_parmlist)
-	    /* You can't declare a new template type in a template
-	       parameter list.  But, you can declare a non-template
-	       type:
-
-	         template <class A*> struct S;
-
-	       is a forward-declaration of `A'.  */
-	    ;
-	  else if (IS_AGGR_TYPE (type)
-	      && (/* If !GLOBALIZE then we are looking at a
-		     definition.  It may not be a primary template.
-		     (For example, in:
-		  
-		       template <class T>
-		       struct S1 { class S2 {}; }
-		  
-		     we have to push_template_decl for S2.)  */
-		  (processing_template_decl && !globalize)
-		  /* If we are declaring a friend template class, we
-		     will have GLOBALIZE set, since something like:
-
-		       template <class T>
-		       struct S1 {
-		         template <class U>
-		         friend class S2; 
-		       };
-
-		     declares S2 to be at global scope.  */
-		  || (processing_template_decl > 
-		      template_class_depth (current_class_type))))
-	    {
-	      d = push_template_decl_real (d, globalize);
-	      /* If the current binding level is the binding level for
-		 the template parameters (see the comment in
-		 begin_template_parm_list) and the enclosing level is
-		 a class scope, and we're not looking at a friend,
-		 push the declaration of the member class into the
-		 class scope.  In the friend case, push_template_decl
-		 will already have put the friend into global scope,
-		 if appropriate.  */ 
-	      if (!globalize && b->pseudo_global
-		  && b->level_chain->parm_flag == 2)
-		{
-		  pushdecl_with_scope (CLASSTYPE_TI_TEMPLATE (type),
-				       b->level_chain);
-		  /* Put this tag on the list of tags for the class,
-		     since that won't happen below because B is not
-		     the class binding level, but is instead the
-		     pseudo-global level.  */
-		  b->level_chain->tags = 
-		    saveable_tree_cons (name, type, b->level_chain->tags);
-		  TREE_NONLOCAL_FLAG (type) = 1;
-		  if (TYPE_SIZE (current_class_type) == NULL_TREE)
-		    CLASSTYPE_TAGS (current_class_type) = b->level_chain->tags;
-		}
-	    }
+	  d = maybe_process_template_type_declaration (type,
+						       globalize, b);
 
 	  if (b->parm_flag == 2)
 	    d = pushdecl_class_level (d);
@@ -11349,8 +11377,7 @@ xref_tag (code_type_node, name, binfo, globalize)
     {
       if (current_class_type 
 	  && template_class_depth (current_class_type) 
-	  && (processing_template_decl 
-	      > template_class_depth (current_class_type)))
+	  && PROCESSING_REAL_TEMPLATE_DECL_P ())
       /* Since GLOBALIZE is non-zero, we are not looking at a
 	 definition of this tag.  Since, in addition, we are currently
 	 processing a (member) template declaration of a template
diff --git a/gcc/cp/friend.c b/gcc/cp/friend.c
index 5a97766..db50258 100644
--- a/gcc/cp/friend.c
+++ b/gcc/cp/friend.c
@@ -354,8 +354,7 @@ do_friend (ctype, declarator, decl, parmdecls, flags, quals, funcdef_flag)
     }
 
   if (TREE_CODE (decl) == FUNCTION_DECL)
-    is_friend_template = processing_template_decl >
-      template_class_depth (current_class_type);
+    is_friend_template = PROCESSING_REAL_TEMPLATE_DECL_P ();
 
   if (ctype)
     {
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 07174a0..9e13916 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -121,6 +121,7 @@ static tree most_specialized PROTO((tree, tree, tree));
 static tree most_specialized_class PROTO((tree, tree));
 static tree most_general_template PROTO((tree));
 static void set_mangled_name_for_template_decl PROTO((tree));
+static int template_class_depth_real PROTO((tree, int));
 
 /* We use TREE_VECs to hold template arguments.  If there is only one
    level of template arguments, then the TREE_VEC contains the
@@ -234,12 +235,19 @@ finish_member_template_decl (template_parameters, decl)
        struct B {};
      };
 
-   A<T>::B<U> has depth two, while A<T> has depth one.  Also,
-   both A<T>::B<int> and A<int>::B<U> have depth one.  */
+   A<T>::B<U> has depth two, while A<T> has depth one.  
+   Both A<T>::B<int> and A<int>::B<U> have depth one, if
+   COUNT_SPECIALIZATIONS is 0 or if they are instantiations, not
+   specializations.  
+
+   This function is guaranteed to return 0 if passed NULL_TREE so
+   that, for example, `template_class_depth (current_class_type)' is
+   always safe.  */
 
 int 
-template_class_depth (type)
+template_class_depth_real (type, count_specializations)
      tree type;
+     int count_specializations;
 {
   int depth;
 
@@ -249,12 +257,25 @@ template_class_depth (type)
        type = TYPE_CONTEXT (type))
     if (CLASSTYPE_TEMPLATE_INFO (type)
 	&& PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (type))
-	&& uses_template_parms (CLASSTYPE_TI_ARGS (type)))
+	&& ((count_specializations
+	     && CLASSTYPE_TEMPLATE_SPECIALIZATION (type))
+	    || uses_template_parms (CLASSTYPE_TI_ARGS (type))))
       ++depth;
 
   return depth;
 }
 
+/* Returns the template nesting level of the indicated class TYPE.
+   Like template_class_depth_real, but instantiations do not count in
+   the depth.  */
+
+int 
+template_class_depth (type)
+     tree type;
+{
+  return template_class_depth_real (type, /*count_specializations=*/0);
+}
+
 /* Returns 1 if processing DECL as part of do_pending_inlines
    needs us to push template parms.  */
 
@@ -742,11 +763,8 @@ register_specialization (spec, tmpl, args)
 	      }
 	    else if (DECL_TEMPLATE_SPECIALIZATION (fn))
 	      {
-		if (DECL_INITIAL (fn))
-		  cp_error ("duplicate specialization of %D", fn);
-
-		TREE_VALUE (s) = spec;
-		return spec;
+		duplicate_decls (spec, TREE_VALUE (s));
+		return TREE_VALUE (s);
 	      }
 	  }
       }
@@ -1300,6 +1318,50 @@ check_explicit_specialization (declarator, decl, template_count, flags)
   return decl;
 }
 
+/* TYPE is being declared.  Verify that the use of template headers
+   and such is reasonable.  Issue error messages if not.  */
+
+void
+maybe_check_template_type (type)
+     tree type;
+{
+  if (template_header_count)
+    {
+      /* We are in the scope of some `template <...>' header.  */
+
+      int context_depth 
+	= template_class_depth_real (TYPE_CONTEXT (type),
+				     /*count_specializations=*/1);
+
+      if (template_header_count <= context_depth)
+	/* This is OK; the template headers are for the context.  We
+	   are actually too lenient here; like
+	   check_explicit_specialization we should consider the number
+	   of template types included in the actual declaration.  For
+	   example, 
+
+	     template <class T> struct S {
+	       template <class U> template <class V>
+	       struct I {};
+	     }; 
+
+	   is illegal, but:
+
+	     template <class T> struct S {
+	       template <class U> struct I;
+	     }; 
+
+	     template <class T> template <class U.
+	     struct S<T>::I {};
+
+	   is not.  */
+	; 
+      else if (template_header_count > context_depth + 1)
+	/* There are two many template parameter lists.  */
+	cp_error ("too many template parameter lists in declaration of `%T'", type); 
+    }
+}
+
 /* Returns 1 iff PARMS1 and PARMS2 are identical sets of template
    parameters.  These are represented in the same format used for
    DECL_TEMPLATE_PARMS.  */
@@ -1951,9 +2013,7 @@ push_template_decl_real (decl, is_friend)
   /* Push template declarations for global functions and types.  Note
      that we do not try to push a global template friend declared in a
      template class; such a thing may well depend on the template
-     parameters of the class.  With guiding declarations, however, we
-     push the template so that subsequent declarations of the template
-     will match this one.  */
+     parameters of the class.  */
   if (! ctx 
       && !(is_friend && template_class_depth (current_class_type) > 0))
     tmpl = pushdecl_namespace_level (tmpl);
@@ -2278,10 +2338,10 @@ convert_nontype_argument (type, expr)
 	if (TREE_CODE (type_referred_to) == FUNCTION_TYPE)
 	  {
 	    /* For a non-type template-parameter of type reference to
-	      function, no conversions apply.  If the
-	      template-argument represents a set of overloaded
-	      functions, the matching function is selected from the
-	      set (_over.over_).  */
+	       function, no conversions apply.  If the
+	       template-argument represents a set of overloaded
+	       functions, the matching function is selected from the
+	       set (_over.over_).  */
 	    tree fns = expr;
 	    tree fn;
 
@@ -3096,7 +3156,7 @@ lookup_template_class (d1, arglist, in_decl, context, entering_scope)
 
       if (arg_depth == 1 && parm_depth > 1)
 	{
-	  /* We've been with an incomplete set of template arguments.
+	  /* We've been given an incomplete set of template arguments.
 	     For example, given:
 
 	       template <class T> struct S1 {
@@ -3109,8 +3169,28 @@ lookup_template_class (d1, arglist, in_decl, context, entering_scope)
 	     <class U> struct S1<T>::S2'.  We must fill in the missing
 	     arguments.  */
 	  my_friendly_assert (context != NULL_TREE, 0);
-	  while (!IS_AGGR_TYPE_CODE (TREE_CODE (context)))
+	  while (!IS_AGGR_TYPE_CODE (TREE_CODE (context))
+		 && context != global_namespace)
 	    context = DECL_REAL_CONTEXT (context);
+
+	  if (context == global_namespace)
+	    /* This is bad.  We cannot get enough arguments, even from
+	       the surrounding context, to resolve this class.  One
+	       case where this might happen is (illegal) code like:
+
+	           template <class U> 
+		   template <class T>
+		   struct S { 
+		     A(const A<T>& a) {}
+		   };  
+	    
+	       We should catch this error sooner (at the opening curly
+	       for `S', but it is better to be safe than sorry here.  */
+	    {
+	      cp_error ("invalid use of `%D'", template);
+	      return error_mark_node;
+	    }
+
 	  arglist = add_to_template_args (CLASSTYPE_TI_ARGS (context),
 					  arglist);
 	  arg_depth = TMPL_ARGS_DEPTH (arglist);
@@ -3667,8 +3747,8 @@ tsubst_friend_function (decl, args)
 						 args, NULL_TREE),
 				    tsubst (DECL_TI_ARGS (decl),
 					    args, NULL_TREE));
-      /* FIXME: The decl we create via the next tsubst be created on a
-	 temporary obstack.  */
+      /* FIXME: The decl we create via the next tsubst could be
+	 created on a temporary obstack.  */
       new_friend = tsubst (decl, args, NULL_TREE);
       tmpl = determine_specialization (template_id, new_friend,
 				       &new_args, 
@@ -4833,12 +4913,14 @@ tsubst (t, args, in_decl)
 		 };
 
 	       Here, the DECL_TI_TEMPLATE for the friend declaration
-	       will be a LOOKUP_EXPR.  We are being called from
-	       tsubst_friend_function, and we want only to create a
-	       new decl (R) with appropriate types so that we can call
-	       determine_specialization.  */
-	    my_friendly_assert (TREE_CODE (DECL_TI_TEMPLATE (t)) 
-				== LOOKUP_EXPR, 0);
+	       will be a LOOKUP_EXPR or an IDENTIFIER_NODE.  We are
+	       being called from tsubst_friend_function, and we want
+	       only to create a new decl (R) with appropriate types so
+	       that we can call determine_specialization.  */
+	    my_friendly_assert ((TREE_CODE (DECL_TI_TEMPLATE (t)) 
+				 == LOOKUP_EXPR)
+				|| (TREE_CODE (DECL_TI_TEMPLATE (t))
+				    == IDENTIFIER_NODE), 0);
 	    gen_tmpl = NULL_TREE;
 	  }
 
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index a6d03e1..fa3dd49 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -1098,6 +1098,10 @@ begin_function_definition (decl_specs, declarator)
     return 0;
   
   reinit_parse_for_function ();
+  /* The things we're about to see are not directly qualified by any
+     template headers we've seen thus far.  */
+  reset_specialization ();
+
   return 1;
 }
 
diff --git a/gcc/testsuite/g++.old-deja/g++.pt/crash15.C b/gcc/testsuite/g++.old-deja/g++.pt/crash15.C
new file mode 100644
index 0000000..75b1054
--- /dev/null
+++ b/gcc/testsuite/g++.old-deja/g++.pt/crash15.C
@@ -0,0 +1,10 @@
+// Build don't link:
+
+template <class T>
+template <class U>
+struct A { // ERROR - too many template parameter lists
+public:
+  A() {}
+
+  A(const A<T>& b) {} // ERROR - invalid use of template
+};
diff --git a/gcc/testsuite/g++.old-deja/g++.pt/enum5.C b/gcc/testsuite/g++.old-deja/g++.pt/enum5.C
new file mode 100644
index 0000000..f6feefb
--- /dev/null
+++ b/gcc/testsuite/g++.old-deja/g++.pt/enum5.C
@@ -0,0 +1,4 @@
+// Build don't link:
+
+template <>
+enum E {e}; // ERROR - template declaration of enum
diff --git a/gcc/testsuite/g++.old-deja/g++.pt/explicit34.C b/gcc/testsuite/g++.old-deja/g++.pt/explicit34.C
index 487525e..0aede38 100644
--- a/gcc/testsuite/g++.old-deja/g++.pt/explicit34.C
+++ b/gcc/testsuite/g++.old-deja/g++.pt/explicit34.C
@@ -4,7 +4,7 @@ template <class T>
 void foo(T t);
 
 template <>
-void foo(int) {}; 
+void foo(int) {}; // ERROR - previously defined here.
 
 template <>
 void foo<int>(int) {} // ERROR - duplicate specialization.
diff --git a/gcc/testsuite/g++.old-deja/g++.pt/friend28.C b/gcc/testsuite/g++.old-deja/g++.pt/friend28.C
new file mode 100644
index 0000000..f86d0b6
--- /dev/null
+++ b/gcc/testsuite/g++.old-deja/g++.pt/friend28.C
@@ -0,0 +1,22 @@
+// Build don't link:
+
+class mystream;
+
+template <class T> class a {
+public:
+	friend mystream& operator>> <>( mystream&, a<T>& thea );
+private:
+	T amember;
+};
+
+template <class T> mystream& operator>>( mystream& s, a<T>& thea );
+
+template<> mystream& operator>> <int>( mystream& s, a<int>& thea );
+
+template class a<int>;
+
+template<> mystream& operator>> <int>( mystream& s, a<int>& thea )
+{
+	thea.amember = 0;
+	return s;
+}
diff --git a/gcc/testsuite/g++.old-deja/g++.pt/friend29.C b/gcc/testsuite/g++.old-deja/g++.pt/friend29.C
new file mode 100644
index 0000000..e141aaa
--- /dev/null
+++ b/gcc/testsuite/g++.old-deja/g++.pt/friend29.C
@@ -0,0 +1,16 @@
+// Build don't link:
+
+template <class T> class a {
+public:
+	friend void foo<>( a<T>& thea );
+private:
+	T amember;
+};
+
+template <class T> void foo( a<T>& thea )
+{
+	thea.amember = 0;
+}
+
+template class a<int>;
+