Merge remote-tracking branch 'origin/maint'

[bison.git] / data / c.m4

diff --git a/data/c.m4 b/data/c.m4
index c0cf9e4d55c1896a1b4161c618bc9aac88822ffb..14db807b2b72e84463d742e5610f9ea9f757fdf1 100644 (file)
--- a/data/c.m4
+++ b/data/c.m4
@@ -124,10 +124,8 @@ m4_popdef([$1])dnl
 # --------------------------------
 # `YYUSE' VAL, LOC if locations are enabled, and all the parse-params.
 m4_define([b4_parse_param_use],
-[m4_ifval([$1], [  YYUSE([$1]);
-])dnl
-m4_ifval([$2], [b4_locations_if([  YYUSE ([$2]);
-])])dnl
+[m4_ifvaln([$1], [  YYUSE([$1]);])dnl
+b4_locations_if([m4_ifvaln([$2], [  YYUSE ([$2]);])])dnl
 b4_parse_param_for([Decl], [Formal], [  YYUSE (Formal);
 ])dnl
 ])
@@ -173,23 +171,37 @@ 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])
 
 # b4_integral_parser_table_define(TABLE-NAME, CONTENT, COMMENT)
 # -------------------------------------------------------------
 # Define "yy<TABLE-NAME>" which contents is CONTENT.
 m4_define([b4_integral_parser_table_define],
-[m4_ifval([$3], [b4_c_comment([$3], [  ])
-])dnl
+[m4_ifvaln([$3], [b4_c_comment([$3], [  ])])dnl
 static const b4_int_type_for([$2]) yy$1[[]] =
 {
   $2
@@ -448,8 +460,8 @@ m4_define_default([b4_yydestruct_generate],
 b4_locations_if(            [, [[YYLTYPE *yylocationp], [yylocationp]]])[]dnl
 m4_ifset([b4_parse_param], [, b4_parse_param]))[
 {
-]b4_parse_param_use([yyvaluep], [yylocationp])[
-  if (!yymsg)
+]b4_parse_param_use([yyvaluep], [yylocationp])dnl
+[  if (!yymsg)
     yymsg = "Deleting";
   YY_SYMBOL_PRINT (yymsg, yytype, yyvaluep, yylocationp);
 
@@ -483,8 +495,8 @@ 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]))[
 {
-]b4_parse_param_use([yyoutput], [yylocationp])[
-  if (!yyvaluep)
+]b4_parse_param_use([yyoutput], [yylocationp])dnl
+[  if (!yyvaluep)
     return;]
 dnl glr.c does not feature yytoknum.
 m4_if(b4_skeleton, ["yacc.c"],