* data/c.m4 (b4_yy_symbol_print_generate): In yy_symbol_print, accept

[bison.git] / data / c.m4

diff --git a/data/c.m4 b/data/c.m4
index d84651079a680f86c63a9906cf60336c762b9867..630fdebd118aba45b158e9a2b265da7f01963cc3 100644 (file)
--- a/data/c.m4
+++ b/data/c.m4
@@ -1,7 +1,7 @@
 m4_divert(-1)                                               -*- Autoconf -*-
 
 # C M4 Macros for Bison.
-# Copyright (C) 2002, 2004, 2005 Free Software Foundation, Inc.
+# Copyright (C) 2002, 2004, 2005, 2006 Free Software Foundation, Inc.
 
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -95,6 +95,7 @@ m4_define_default([b4_parse_param])
 m4_define([b4_parse_param],
 b4_parse_param))
 
+
 # b4_parse_param_for(DECL, FORMAL, BODY)
 # ---------------------------------------
 # Iterate over the user parameters, binding the declaration to DECL,
@@ -247,11 +248,25 @@ m4_define([b4_token_enums_defines],
 ## --------------------------------------------- ##
 
 
+# b4_modern_c
+# -----------
+# A predicate useful in #if to determine whether C is ancient or modern.
+#
+# If __STDC__ is defined, the compiler is modern.  IBM xlc 7.0 when run
+# as 'cc' doesn't define __STDC__ (or __STDC_VERSION__) for pedantic
+# reasons, but it defines __C99__FUNC__ so check that as well.
+# Microsoft C normally doesn't define these macros, but it defines _MSC_VER.
+# Consider a C++ compiler to be modern if it defines __cplusplus.
+#
+m4_define([b4_c_modern],
+  [[(defined (__STDC__) || defined (__C99__FUNC__) \
+     || defined (__cplusplus) || defined (_MSC_VER))]])
+
 # b4_c_function_def(NAME, RETURN-VALUE, [DECL1, NAME1], ...)
 # ----------------------------------------------------------
 # Declare the function NAME.
 m4_define([b4_c_function_def],
-[#if defined (__STDC__) || defined (__C99__FUNC__) || defined (__cplusplus)
+[#if b4_c_modern
 b4_c_ansi_function_def($@)
 #else
 $2
@@ -449,7 +464,8 @@ m4_define_default([b4_yy_symbol_print_generate],
 b4_location_if([, [[const YYLTYPE * const yylocationp], [yylocationp]]])[]dnl
 m4_ifset([b4_parse_param], [, b4_parse_param]))[
 {
-  YYUSE (yyvaluep);
+  if (!yyvaluep)
+    return;
 ]b4_location_if([  YYUSE (yylocationp);
 ])dnl
 b4_parse_param_use[]dnl