From 5367a58ed3e350649584843df74eb2c90825a044 Mon Sep 17 00:00:00 2001
From: nathan <nathan@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Fri, 31 Aug 2018 11:19:33 +0000
Subject: [PATCH] [C++ PATCH] Remove K&R declaration hack.

https://gcc.gnu.org/ml/gcc-patches/2018-08/msg01885.html
	gcc/
	* doc/extend.texi (Backwards Compatibility): Remove implicit
	extern C leeway of () being (...).
	gcc/cp/
	* decl.c (decls_match): Remove SYSTEM_IMPLICIT_EXTERN_C matching
	of return types and parms.
	* parser.c (cp_parser_parameter_declaration_clause): Likewise,
	'()' always means '(void)'.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@264013 138bc75d-0d04-0410-961f-82ee72b054a4
---
 gcc/ChangeLog       |  5 +++++
 gcc/cp/ChangeLog    |  7 +++++++
 gcc/cp/decl.c       | 20 +-------------------
 gcc/cp/parser.c     | 11 +----------
 gcc/doc/extend.texi |  6 +++---
 5 files changed, 17 insertions(+), 32 deletions(-)

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 05ccec37f99..1fbcbd5bea5 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2018-08-31  Nathan Sidwell  <nathan@acm.org>
+
+	* doc/extend.texi (Backwards Compatibility): Remove implicit
+	extern C leeway of () being (...).
+
 2018-08-31  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
 	* ipa-inline.c (can_inline_edge_by_limits_p): Fix typos in comment.
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 6ecd48dfac8..0c5a4bf71c5 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,10 @@
+2018-08-31  Nathan Sidwell  <nathan@acm.org>
+
+	* decl.c (decls_match): Remove SYSTEM_IMPLICIT_EXTERN_C matching
+	of return types and parms.
+	* parser.c (cp_parser_parameter_declaration_clause): Likewise,
+	'()' always means '(void)'.
+
 2018-08-29  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/87095
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index c6711f74177..d743e6fef25 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -968,30 +968,12 @@ decls_match (tree newdecl, tree olddecl, bool record_versions /* = true */)
       if (same_type_p (TREE_TYPE (f1), r2))
 	{
 	  if (!prototype_p (f2) && DECL_EXTERN_C_P (olddecl)
-	      && (fndecl_built_in_p (olddecl)
-#ifdef SYSTEM_IMPLICIT_EXTERN_C
-		  || (DECL_IN_SYSTEM_HEADER (newdecl) && !DECL_CLASS_SCOPE_P (newdecl))
-		  || (DECL_IN_SYSTEM_HEADER (olddecl) && !DECL_CLASS_SCOPE_P (olddecl))
-#endif
-	      ))
+	      && fndecl_built_in_p (olddecl))
 	    {
 	      types_match = self_promoting_args_p (p1);
 	      if (p1 == void_list_node)
 		TREE_TYPE (newdecl) = TREE_TYPE (olddecl);
 	    }
-#ifdef SYSTEM_IMPLICIT_EXTERN_C
-	  else if (!prototype_p (f1)
-		   && (DECL_EXTERN_C_P (olddecl)
-		       && DECL_IN_SYSTEM_HEADER (olddecl)
-		       && !DECL_CLASS_SCOPE_P (olddecl))
-		   && (DECL_EXTERN_C_P (newdecl)
-		       && DECL_IN_SYSTEM_HEADER (newdecl)
-		       && !DECL_CLASS_SCOPE_P (newdecl)))
-	    {
-	      types_match = self_promoting_args_p (p2);
-	      TREE_TYPE (newdecl) = TREE_TYPE (olddecl);
-	    }
-#endif
 	  else
 	    types_match =
 	      compparms (p1, p2)
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 92e6b40efb4..f5e4fa4ff07 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -21378,16 +21378,7 @@ cp_parser_parameter_declaration_clause (cp_parser* parser)
     }
   else if (token->type == CPP_CLOSE_PAREN)
     /* There are no parameters.  */
-    {
-#ifdef SYSTEM_IMPLICIT_EXTERN_C
-      if (in_system_header_at (input_location)
-	  && current_class_type == NULL
-	  && current_lang_name == lang_name_c)
-	return NULL_TREE;
-      else
-#endif
-	return void_list_node;
-    }
+    return void_list_node;
   /* Check for `(void)', too, which is a special case.  */
   else if (token->keyword == RID_VOID
 	   && (cp_lexer_peek_nth_token (parser->lexer, 2)->type
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index e3312aa8b42..9c3cfdbf022 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -23685,9 +23685,9 @@ deprecated.   @xref{Deprecated Features}.
 @item Implicit C language
 Old C system header files did not contain an @code{extern "C" @{@dots{}@}}
 scope to set the language.  On such systems, all system header files are
-implicitly scoped inside a C language scope.  Also, an empty prototype
-@code{()} is treated as an unspecified number of arguments, rather
-than no arguments, as C++ demands.
+implicitly scoped inside a C language scope.  Such headers must
+correctly prototype function argument types, there is no leeway for
+@code{()} to indicate an unspecified set of arguments.
 
 @end table
 
-- 
2.11.4.GIT