extend.texi: Mark named return value extension as deprecated.

	* extend.texi: Mark named return value extension as deprecated.

	* NEWS: Mention that the named return value extension has been
	deprecated.
	* cp-tree.h (original_result_rtx): Define.
	(TREE_REFERENCE_EXPR): Remove.
	(DECL_VPARENT): Likewise.
	(pushdecl_nonclass_level): Likewise.
	(store_return_init): Likewise.
	(reinit_lang_specific): Likewise.
	(genrtl_named_return_value): Change prototype.
	* decl.c (original_result_rtx): Remove.
	(cp_finish_decl): Don't build DECL_STMTs for RESULT_DECLs.
	Do not generate RTL for local variables here.
	(store_return_init): Remove.
	* semantics.c (genrtl_named_return_value): Simplify.  Fold in
	store_return_init.
	(finish_named_return_value): Adjust accordingly.  Warn that this
	extension is deprecated.
	(lang_expand_stmt): Adjust call to genrtl_named_return_value.

From-SVN: r36210

gcc/ChangeLog

+2000-09-06  Mark Mitchell  <mark@codesourcery.com>
+
+	* extend.texi: Mark named return value extension as deprecated.
+
 2000-09-06  Geoff Keating  <geoffk@cygnus.com>
 
 	* config/rs6000/rs6000.c (rs6000_reverse_condition): Return

gcc/c-common.h

@@ -521,3 +521,5 @@ extern tree default_conversion                  PARAMS ((tree));
    Given two compatible ANSI C types, returns the merged type.  */
 
 extern tree common_type                         PARAMS ((tree, tree));
+
+extern tree expand_tree_builtin                 PARAMS ((tree, tree, tree));

gcc/cp/ChangeLog

+2000-09-06  Mark Mitchell  <mark@codesourcery.com>
+
+	* NEWS: Mention that the named return value extension has been
+	deprecated.
+	* cp-tree.h (original_result_rtx): Define.
+	(TREE_REFERENCE_EXPR): Remove.
+	(DECL_VPARENT): Likewise.
+	(pushdecl_nonclass_level): Likewise.
+	(store_return_init): Likewise.
+	(reinit_lang_specific): Likewise.
+	(genrtl_named_return_value): Change prototype.
+	* decl.c (original_result_rtx): Remove.
+	(cp_finish_decl): Don't build DECL_STMTs for RESULT_DECLs.
+	Do not generate RTL for local variables here.
+	(store_return_init): Remove.
+	* semantics.c (genrtl_named_return_value): Simplify.  Fold in
+	store_return_init.
+	(finish_named_return_value): Adjust accordingly.  Warn that this
+	extension is deprecated.
+	(lang_expand_stmt): Adjust call to genrtl_named_return_value.
+
 2000-09-06  Nathan Sidwell  <nathan@codesourcery.com>
 
 	* pt.c (type_unification_real): Replace switch with if.

gcc/cp/NEWS

@@ -36,6 +36,12 @@
 * G++ no longer allows you to overload the conditional operator (i.e., 
   the `?:' operator.)
 
+* The "named return value" extension:
+	
+    int f () return r { r = 3; }
+
+  has been deprecated, and will be removed in a future version of G++.
+
 *** Changes in GCC 2.95:
 
 * Messages about non-conformant code that we can still handle ("pedwarns")

gcc/cp/cp-tree.h

@@ -1009,6 +1009,13 @@ struct language_function
 
 #define doing_semantic_analysis_p() (!expanding_p)
 
+/* If original DECL_RESULT of current function was a register,
+   but due to being an addressable named return value, would up
+   on the stack, this variable holds the named return value's
+   original location.  */
+
+#define original_result_rtx cp_function_chain->x_result_rtx
+
 #define in_function_try_handler cp_function_chain->in_function_try_handler
 
 extern tree current_function_return_value;
@@ -2588,13 +2595,6 @@ extern int flag_new_for_scope;
 				   && CONSTRUCTOR_ELTS (NODE) == NULL_TREE \
 				   && ! TREE_HAS_CONSTRUCTOR (NODE))
 
-#if 0
-/* Indicates that a NON_LVALUE_EXPR came from a C++ reference.
-   Used to generate more helpful error message in case somebody
-   tries to take its address.  */
-#define TREE_REFERENCE_EXPR(NODE) (TREE_LANG_FLAG_3(NODE))
-#endif
-
 /* Nonzero for _TYPE means that the _TYPE defines a destructor.  */
 #define TYPE_HAS_DESTRUCTOR(NODE) (TYPE_LANG_FLAG_2(NODE))
 
@@ -2804,18 +2804,6 @@ extern int flag_new_for_scope;
 
 /* Define fields and accessors for nodes representing declared names.  */
 
-#if 0
-/* C++: A derived class may be able to directly use the virtual
-   function table of a base class.  When it does so, it may
-   still have a decl node used to access the virtual function
-   table (so that variables of this type can initialize their
-   virtual function table pointers by name).  When such thievery
-   is committed, know exactly which base class's virtual function
-   table is the one being stolen.  This effectively computes the
-   transitive closure.  */
-#define DECL_VPARENT(NODE) ((NODE)->decl.arguments)
-#endif
-
 #define TYPE_WAS_ANONYMOUS(NODE) (TYPE_LANG_SPECIFIC (NODE)->was_anonymous)
 
 /* C++: all of these are overloaded!  These apply only to TYPE_DECLs.  */
@@ -3903,9 +3891,6 @@ extern int duplicate_decls			PARAMS ((tree, tree));
 extern tree pushdecl				PARAMS ((tree));
 extern tree pushdecl_top_level			PARAMS ((tree));
 extern void pushdecl_class_level		PARAMS ((tree));
-#if 0
-extern void pushdecl_nonclass_level		PARAMS ((tree));
-#endif
 extern tree pushdecl_namespace_level            PARAMS ((tree));
 extern tree push_using_decl                     PARAMS ((tree, tree));
 extern tree push_using_directive                PARAMS ((tree));
@@ -3918,9 +3903,6 @@ extern void check_goto				PARAMS ((tree));
 extern void define_case_label			PARAMS ((void));
 extern tree getdecls				PARAMS ((void));
 extern tree gettags				PARAMS ((void));
-#if 0
-extern void set_current_level_tags_transparency	PARAMS ((int));
-#endif
 extern tree binding_for_name                    PARAMS ((tree, tree));
 extern tree namespace_binding                   PARAMS ((tree, tree));
 extern void set_namespace_binding               PARAMS ((tree, tree, tree));
@@ -3974,7 +3956,6 @@ extern void build_enumerator			PARAMS ((tree, tree, tree));
 extern int start_function			PARAMS ((tree, tree, tree, int));
 extern void expand_start_early_try_stmts	PARAMS ((void));
 extern void store_parm_decls			PARAMS ((void));
-extern void store_return_init			PARAMS ((tree));
 extern tree finish_function			PARAMS ((int));
 extern tree start_method			PARAMS ((tree, tree, tree));
 extern tree finish_method			PARAMS ((tree));
@@ -4166,9 +4147,6 @@ extern tree make_call_declarator		PARAMS ((tree, tree, tree, tree));
 extern void set_quals_and_spec			PARAMS ((tree, tree, tree));
 extern void lang_init				PARAMS ((void));
 extern void lang_finish				PARAMS ((void));
-#if 0
-extern void reinit_lang_specific		PARAMS ((void));
-#endif
 extern void print_parse_statistics		PARAMS ((void));
 extern void extract_interface_info		PARAMS ((void));
 extern void do_pending_inlines			PARAMS ((void));
@@ -4464,8 +4442,7 @@ extern void genrtl_ctor_stmt                    PARAMS ((tree));
 extern void genrtl_subobject                    PARAMS ((tree));
 extern tree genrtl_do_poplevel                  PARAMS ((void));
 extern void clear_out_block                     PARAMS ((void));
-extern void genrtl_named_return_value           PARAMS ((tree,
-							 tree));
+extern void genrtl_named_return_value           PARAMS ((void));
 extern tree begin_global_stmt_expr              PARAMS ((void));
 extern tree finish_global_stmt_expr             PARAMS ((tree));
 

gcc/cp/decl.c

@@ -269,13 +269,6 @@ int in_std;
 /* Expect only namespace names now. */
 static int only_namespace_names;
 
-/* If original DECL_RESULT of current function was a register,
-   but due to being an addressable named return value, would up
-   on the stack, this variable holds the named return value's
-   original location.  */
-
-#define original_result_rtx cp_function_chain->x_result_rtx
-
 /* Used only for jumps to as-yet undefined labels, since jumps to
    defined labels can have their validity checked immediately.  */
 
@@ -8092,7 +8085,9 @@ cp_finish_decl (decl, init, asmspec_tree, flags)
     return;
   
   /* Add this declaration to the statement-tree.  */
-  if (building_stmt_tree () && at_function_scope_p ())
+  if (building_stmt_tree () 
+      && at_function_scope_p ()
+      && TREE_CODE (decl) != RESULT_DECL)
     add_decl_stmt (decl);
 
   if (TYPE_HAS_MUTABLE_P (type))
@@ -8215,8 +8210,7 @@ cp_finish_decl (decl, init, asmspec_tree, flags)
 	    {
 	      /* If we're not building RTL, then we need to do so
 		 now.  */
-	      if (!building_stmt_tree ())
-		emit_local_var (decl);
+	      my_friendly_assert (building_stmt_tree (), 20000906);
 	      /* Initialize the variable.  */
 	      initialize_local_var (decl, init, flags);
 	      /* Clean up the variable.  */
@@ -14034,31 +14028,6 @@ store_parm_decls ()
     current_eh_spec_try_block = expand_start_eh_spec ();
 }
 
-/* Bind a name and initialization to the return value of
-   the current function.  */
-
-void
-store_return_init (decl)
-     tree decl;
-{
-  /* If this named return value comes in a register, put it in a
-     pseudo-register.  */
-  if (DECL_REGISTER (decl))
-    {
-      original_result_rtx = DECL_RTL (decl);
-      /* Note that the mode of the old DECL_RTL may be wider than the
-	 mode of DECL_RESULT, depending on the calling conventions for
-	 the processor.  For example, on the Alpha, a 32-bit integer
-	 is returned in a DImode register -- the DECL_RESULT has
-	 SImode but the DECL_RTL for the DECL_RESULT has DImode.  So,
-	 here, we use the mode the back-end has already assigned for
-	 the return value.  */
-      DECL_RTL (decl) = gen_reg_rtx (GET_MODE (original_result_rtx));
-      if (TREE_ADDRESSABLE (decl))
-	put_var_into_stack (decl);
-    }
-}
-
 
 /* We have finished doing semantic analysis on DECL, but have not yet
    generated RTL for its body.  Save away our current state, so that

gcc/cp/semantics.c

@@ -1030,55 +1030,30 @@ finish_decl_cleanup (decl, cleanup)
 /* Generate the RTL for a RETURN_INIT. */
 
 void
-genrtl_named_return_value (return_id, init)
-     tree return_id, init;
+genrtl_named_return_value ()
 {
   tree decl;
-  /* Clear this out so that finish_named_return_value can set it
-     again.  */
-  DECL_NAME (DECL_RESULT (current_function_decl)) = NULL_TREE;
 
   decl = DECL_RESULT (current_function_decl);
-  if (pedantic)
-    /* Give this error as many times as there are occurrences,
-       so that users can use Emacs compilation buffers to find
-       and fix all such places.  */
-    pedwarn ("ISO C++ does not permit named return values");
 
-  if (return_id != NULL_TREE)
-    {
-      if (DECL_NAME (decl) == NULL_TREE)
-	{
-	  DECL_NAME (decl) = return_id;
-	  DECL_ASSEMBLER_NAME (decl) = return_id;
-	}
-      else
-	{
-	  cp_error ("return identifier `%D' already in place", return_id);
-	  return;
-	}
-    }
+  emit_local_var (decl);
 
-  /* Can't let this happen for constructors.  */
-  if (DECL_CONSTRUCTOR_P (current_function_decl))
+  /* If this named return value comes in a register, put it in a
+     pseudo-register.  */
+  if (DECL_REGISTER (decl))
     {
-      error ("can't redefine default return value for constructors");
-      return;
-    }
-
-  /* If we have a named return value, put that in our scope as well.  */
-  if (DECL_NAME (decl) != NULL_TREE)
-    {
-      /* Let `cp_finish_decl' know that this initializer is ok.  */
-      DECL_INITIAL (decl) = init;
-      cp_finish_decl (decl, init, NULL_TREE, 0);
-      store_return_init (decl);
+      original_result_rtx = DECL_RTL (decl);
+      /* Note that the mode of the old DECL_RTL may be wider than the
+	 mode of DECL_RESULT, depending on the calling conventions for
+	 the processor.  For example, on the Alpha, a 32-bit integer
+	 is returned in a DImode register -- the DECL_RESULT has
+	 SImode but the DECL_RTL for the DECL_RESULT has DImode.  So,
+	 here, we use the mode the back-end has already assigned for
+	 the return value.  */
+      DECL_RTL (decl) = gen_reg_rtx (GET_MODE (original_result_rtx));
+      if (TREE_ADDRESSABLE (decl))
+	put_var_into_stack (decl);
     }
-
-  /* Don't use tree-inlining for functions with named return values.
-     That doesn't work properly because we don't do any translation of
-     the RETURN_INITs when they are copied.  */
-  DECL_UNINLINABLE (current_function_decl) = 1;
 }
 
 /* Bind a name and initialization to the return value of
@@ -1090,11 +1065,12 @@ finish_named_return_value (return_id, init)
 {
   tree decl = DECL_RESULT (current_function_decl);
 
+  /* Give this error as many times as there are occurrences, so that
+     users can use Emacs compilation buffers to find and fix all such
+     places.  */
   if (pedantic)
-    /* Give this error as many times as there are occurrences,
-       so that users can use Emacs compilation buffers to find
-       and fix all such places.  */
     pedwarn ("ISO C++ does not permit named return values");
+  cp_deprecated ("the named return value extension");
 
   if (return_id != NULL_TREE)
     {
@@ -1124,7 +1100,13 @@ finish_named_return_value (return_id, init)
       DECL_INITIAL (decl) = init;
       if (doing_semantic_analysis_p ())
 	pushdecl (decl);
-      add_tree (build_stmt (RETURN_INIT, return_id, init));
+      if (!processing_template_decl) 
+	{
+	  cp_finish_decl (decl, init, NULL_TREE, 0);
+	  add_tree (build_stmt (RETURN_INIT, NULL_TREE, NULL_TREE));
+	}
+      else
+	add_tree (build_stmt (RETURN_INIT, return_id, init));
     }
 
   /* Don't use tree-inlining for functions with named return values.
@@ -2463,8 +2445,7 @@ lang_expand_stmt (t)
 	  break;
 
 	case RETURN_INIT:
-	  genrtl_named_return_value (TREE_OPERAND (t, 0), 
-				     TREE_OPERAND (t, 1));
+	  genrtl_named_return_value ();
 	  break;
 
 	default:

gcc/extend.texi

@@ -3333,9 +3333,11 @@ Previously it was possible to use an empty prototype parameter list to
 indicate an unspecified number of parameters (like C), rather than no
 parameters, as C++ demands. This feature has been removed, except where
 it is required for backwards compatibility @xref{Backwards Compatibility}.
-
 @end table
 
+The named return value extension has been deprecated, and will be
+removed from g++ at some point.
+
 @node Backwards Compatibility
 @section Backwards Compatibility
 @cindex Backwards Compatibility
@@ -3379,7 +3381,6 @@ test specifically for GNU C++ (@pxref{Standard Predefined,,Standard
 Predefined Macros,cpp.info,The C Preprocessor}).
 
 @menu
-* Naming Results::      Giving a name to C++ function return values.
 * Min and Max::		C++ Minimum and maximum operators.
 * Volatiles::		What constitutes an access to a volatile object.
 * Restricted Pointers:: C99 restricted pointers and references.
@@ -3391,119 +3392,6 @@ Predefined Macros,cpp.info,The C Preprocessor}).
                         method denoted by a @samp{->*} or @samp{.*} expression.
 @end menu
 
-@node Naming Results
-@section Named Return Values in C++
-
-@cindex @code{return}, in C++ function header
-@cindex return value, named, in C++
-@cindex named return value in C++
-@cindex C++ named return value
-GNU C++ extends the function-definition syntax to allow you to specify a
-name for the result of a function outside the body of the definition, in
-C++ programs:
-
-@example
-@group
-@var{type}
-@var{functionname} (@var{args}) return @var{resultname};
-@{
-  @dots{}
-  @var{body}
-  @dots{}
-@}
-@end group
-@end example
-
-You can use this feature to avoid an extra constructor call when
-a function result has a class type.  For example, consider a function
-@code{m}, declared as @w{@samp{X v = m ();}}, whose result is of class
-@code{X}:
-
-@example
-X
-m ()
-@{
-  X b;
-  b.a = 23;
-  return b;
-@}
-@end example
-
-@cindex implicit argument: return value
-Although @code{m} appears to have no arguments, in fact it has one implicit
-argument: the address of the return value.  At invocation, the address
-of enough space to hold @code{v} is sent in as the implicit argument.
-Then @code{b} is constructed and its @code{a} field is set to the value
-23.  Finally, a copy constructor (a constructor of the form @samp{X(X&)})
-is applied to @code{b}, with the (implicit) return value location as the
-target, so that @code{v} is now bound to the return value.
-
-But this is wasteful.  The local @code{b} is declared just to hold
-something that will be copied right out.  While a compiler that
-combined an ``elision'' algorithm with interprocedural data flow
-analysis could conceivably eliminate all of this, it is much more
-practical to allow you to assist the compiler in generating
-efficient code by manipulating the return value explicitly,
-thus avoiding the local variable and copy constructor altogether.
-
-Using the extended GNU C++ function-definition syntax, you can avoid the
-temporary allocation and copying by naming @code{r} as your return value
-at the outset, and assigning to its @code{a} field directly:
-
-@example
-X
-m () return r;
-@{
-  r.a = 23;
-@}
-@end example
-
-@noindent
-The declaration of @code{r} is a standard, proper declaration, whose effects
-are executed @strong{before} any of the body of @code{m}.
-
-Functions of this type impose no additional restrictions; in particular,
-you can execute @code{return} statements, or return implicitly by
-reaching the end of the function body (``falling off the edge'').
-Cases like
-
-@example
-X
-m () return r (23);
-@{
-  return;
-@}
-@end example
-
-@noindent
-(or even @w{@samp{X m () return r (23); @{ @}}}) are unambiguous, since
-the return value @code{r} has been initialized in either case.  The
-following code may be hard to read, but also works predictably:
-
-@example
-X
-m () return r;
-@{
-  X b;
-  return b;
-@}
-@end example
-
-The return value slot denoted by @code{r} is initialized at the outset,
-but the statement @samp{return b;} overrides this value.  The compiler
-deals with this by destroying @code{r} (calling the destructor if there
-is one, or doing nothing if there is not), and then reinitializing
-@code{r} with @code{b}.
-
-This extension is provided primarily to help people who use overloaded
-operators, where there is a great need to control not just the
-arguments, but the return values of functions.  For classes where the
-copy constructor incurs a heavy performance penalty (especially in the
-common case where there is a quick default constructor), this is a major
-savings.  The disadvantage of this extension is that you do not control
-when the default constructor for the return value is called: it is
-always called at the beginning.
-
 @node Min and Max
 @section Minimum and Maximum Operators in C++
 

gcc/testsuite/g++.old-deja/g++.benjamin/p13417.C

 // Build don't link:
-// Special g++ Options:  
+// Special g++ Options: -Wno-deprecated
 // prms-id: 13417
 
 class   Foo {

gcc/testsuite/g++.old-deja/g++.ext/return1.C

 // Test that the named return value extension works when passed as a reference.
 // Origin: Jason Merrill <jason@redhat.com>
-// Special g++ Options:
+// Special g++ Options: -Wno-deprecated
 
 void f (int &i)
 {

gcc/testsuite/g++.old-deja/g++.mike/p646.C

@@ -6,7 +6,7 @@
 */
 
 
-// Special g++ Options: 
+// Special g++ Options: -Wno-deprecated
 
 extern "C"
 {

gcc/testsuite/g++.old-deja/g++.mike/p700.C

-// Special g++ Options:
+// Special g++ Options: -Wno-deprecated
 // prms-id: 700
 
 //# 1 "../../../../libg++/etc/benchmarks/dhrystone.cc"

gcc/testsuite/g++.old-deja/g++.oliva/nameret1.C

 // Build don't link:
-// Copyright (C) 1999 Free Software Foundation
+// Copyright (C) 1999, 2000 Free Software Foundation
 
 // by Alexandre Oliva <oliva@lsd.ic.unicamp.br>
 
 // distilled from libg++'s Rational.cc
 
-// Special g++ Options:
+// Special g++ Options: -Wno-deprecated
 
 inline int bar () return r {}
 

gcc/testsuite/g++.old-deja/g++.oliva/nameret2.C

 // Build don't link:
-// Copyright (C) 1999 Free Software Foundation
+// Copyright (C) 1999, 2000 Free Software Foundation
 
 // by Alexandre Oliva <oliva@lsd.ic.unicamp.br>
 
 // distilled from libg++'s Integer.cc
 
-// Special g++ Options: -O1
+// Special g++ Options: -O1 -Wno-deprecated
 
 inline int bar () return r {}
 

gcc/testsuite/g++.old-deja/g++.robertl/eb101.C

-// Special g++ Options: -fcheck-memory-usage
+// Special g++ Options: -fcheck-memory-usage -Wno-deprecated
 // Build don't link: 
 
  

gcc/testsuite/g++.old-deja/g++.robertl/eb27.C

@@ -2,7 +2,7 @@
 /* simple program to demonstrate the bug with named return values in gcc
 */
 /* (w) 4.9.97 by Kurt Garloff <K.Garloff@ping.de> */
-// Special g++ Options:
+// Special g++ Options: -Wno-deprecated
 // 8/28/1998 - This dies in add_conversions from dfs_walk, null CLASSTYPE_METHOD_VEC
 // for the test<T> record_type.  This is marked as an expected failure for now,
 // until we actually fix it.