X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/c932d6135ca3e508f7136810b9b0bf79725290b9..a0cd287e64e2d53bc5896e0a7c5ad072cb8bf469:/data/c.m4

diff --git a/data/c.m4 b/data/c.m4
index e0e58cdb..fee006a3 100644
--- a/data/c.m4
+++ b/data/c.m4
@@ -146,16 +146,31 @@ m4_define([b4_table_value_equals],
        [[YYID (0)]],
        [[((]$2[) == (]$3[))]])])
 
+
 ## ---------##
 ## Values.  ##
 ## ---------##
 
-# b4_null
----------
-# Return a null pointer constant.  NULL infringes on the user name
-# space in C, so use 0 rather than NULL.
-m4_define([b4_null], [0])
 
+# b4_null_define
+# --------------
+# Portability issues: define a YY_NULL appropriate for the current
+# language (C, C++98, or C++11).
+m4_define([b4_null_define],
+[# ifndef YY_NULL
+#  if defined __cplusplus && 201103L <= __cplusplus
+#   define YY_NULL nullptr
+#  else
+#   define YY_NULL 0
+#  endif
+# endif[]dnl
+])
+
+
+# b4_null
+# -------
+# Return a null pointer constant.
+m4_define([b4_null], [YY_NULL])
 
 
 
@@ -441,6 +456,8 @@ m4_define_default([b4_yy_symbol_print_generate],
 b4_locations_if([, [[YYLTYPE const * const yylocationp], [yylocationp]]])[]dnl
 m4_ifset([b4_parse_param], [, b4_parse_param]))[
 {
+  FILE *yyo = yyoutput;
+  YYUSE (yyo);
   if (!yyvaluep)
     return;
 ]b4_locations_if([  YYUSE (yylocationp);