c++: do not export YYTOKEN_TABLE and YYERROR_VERBOSE.

* src/output.c (prepare_symbols): Do not define b4_token_table.
(prepare): Define b4_token_table_flag.
* data/bison.m4 (b4_token_table_if): New.
Arm it when error-verbose.
* data/glr.c, data/yacc.c (YYTOKEN_TABLE): Remove.
Use m4.
* data/lalr1.cc: Likewise.
(YYERROR_VERBOSE): Remove.
* NEWS, doc/bison.texi: Document this.

data/bison.m4

@@ -233,9 +233,9 @@ m4_define([b4_define_flag_if],
 
 # _b4_define_flag_if($1, $2, FLAG)
 # --------------------------------
-# This macro works around the impossibility to define macros
-# inside macros, because issuing `[$1]' is not possible in M4 :(.
-# This sucks hard, GNU M4 should really provide M5 like $$1.
+# Work around the impossibility to define macros inside macros,
+# because issuing `[$1]' is not possible in M4.  GNU M4 should provide
+# $$1 a la M5/TeX.
 m4_define([_b4_define_flag_if],
 [m4_if([$1$2], $[1]$[2], [],
        [m4_fatal([$0: Invalid arguments: $@])])dnl
@@ -246,12 +246,16 @@ m4_define([b4_$3_if],
 # b4_FLAG_if(IF-TRUE, IF-FALSE)
 # -----------------------------
 # Expand IF-TRUE, if FLAG is true, IF-FALSE otherwise.
-b4_define_flag_if([defines])	        # Whether headers are requested.
-b4_define_flag_if([error_verbose])	# Whether error are verbose.
-b4_define_flag_if([glr])		# Whether a GLR parser is requested.
-b4_define_flag_if([locations])	        # Whether locations are tracked.
-b4_define_flag_if([nondeterministic])	# Whether conflicts should be handled.
-b4_define_flag_if([yacc])	        # Whether POSIX Yacc is emulated.
+b4_define_flag_if([defines])            # Whether headers are requested.
+b4_define_flag_if([error_verbose])      # Whether error are verbose.
+b4_define_flag_if([glr])                # Whether a GLR parser is requested.
+b4_define_flag_if([locations])          # Whether locations are tracked.
+b4_define_flag_if([nondeterministic])   # Whether conflicts should be handled.
+b4_define_flag_if([token_table])        # Whether yytoken_table is demanded.
+b4_define_flag_if([yacc])               # Whether POSIX Yacc is emulated.
+
+# yytoken_table is needed to support verbose errors.
+b4_error_verbose_if([m4_define([b4_token_table_flag], [1])])
 
 
 ## ------------------------- ##

data/glr.c

@@ -215,11 +215,6 @@ b4_percent_code_get([[top]])[
 # define YYERROR_VERBOSE ]b4_error_verbose_flag[
 #endif
 
-/* Enabling the token table.  */
-#ifndef YYTOKEN_TABLE
-# define YYTOKEN_TABLE ]b4_token_table[
-#endif
-
 /* Default (constant) value used for initialization for null
    right-hand sides.  Unlike the standard yacc.c template,
    here we set the default value of $$ to a zeroed-out value.
@@ -367,7 +362,7 @@ static const ]b4_int_type_for([b4_rline])[ yyrline[] =
 };
 #endif
 
-#if YYDEBUG || YYERROR_VERBOSE || YYTOKEN_TABLE
+#if YYDEBUG || YYERROR_VERBOSE || ]b4_token_table_flag[
 /* YYTNAME[SYMBOL-NUM] -- String name of the symbol SYMBOL-NUM.
    First, the terminals, then, starting at YYNTOKENS, nonterminals.  */
 static const char *const yytname[] =

data/lalr1.cc

@@ -62,19 +62,6 @@ b4_copyright([Skeleton interface for Bison LALR(1) parsers in C++],
 # define YYDEBUG ]b4_debug_flag[
 #endif
 
-/* Enabling verbose error messages.  */
-#ifdef YYERROR_VERBOSE
-# undef YYERROR_VERBOSE
-# define YYERROR_VERBOSE 1
-#else
-# define YYERROR_VERBOSE ]b4_error_verbose_flag[
-#endif
-
-/* Enabling the token table.  */
-#ifndef YYTOKEN_TABLE
-# define YYTOKEN_TABLE ]b4_token_table[
-#endif
-
 ]b4_namespace_open[
 
   /// A Bison parser.
@@ -211,17 +198,15 @@ b4_user_stype
     /// For a rule, its LHS.
     static const ]b4_int_type_for([b4_r1])[ yyr1_[];
     /// For a rule, its RHS length.
-    static const ]b4_int_type_for([b4_r2])[ yyr2_[];
-
-#if YYDEBUG || YYERROR_VERBOSE || YYTOKEN_TABLE
-    /// For a symbol, its name in clear.
-    static const char* const yytname_[];
-#endif]b4_error_verbose_if([
+    static const ]b4_int_type_for([b4_r2])[ yyr2_[]; ]b4_error_verbose_if([
 
     /// Convert the symbol name \a n to a form suitable for a diagnostic.
     static std::string yytnamerr_ (const char *n);])[
 
-#if YYDEBUG
+]b4_token_table_if([], [[#if YYDEBUG]])[
+    /// For a symbol, its name in clear.
+    static const char* const yytname_[];
+]b4_token_table_if([[#if YYDEBUG]])[
     /// A type to store symbol numbers and -1.
     typedef ]b4_int_type_for([b4_rhs])[ rhs_number_type;
     /// A `-1'-separated list of the rules' RHS.
@@ -1051,7 +1036,7 @@ b4_error_verbose_if([int yystate, int yytoken],
     ]b4_r2[
   };
 
-#if YYDEBUG || YYERROR_VERBOSE || YYTOKEN_TABLE
+]b4_token_table_if([], [[#if YYDEBUG]])[
   /* YYTNAME[SYMBOL-NUM] -- String name of the symbol SYMBOL-NUM.
      First, the terminals, then, starting at \a yyntokens_, nonterminals.  */
   const char*
@@ -1059,9 +1044,8 @@ b4_error_verbose_if([int yystate, int yytoken],
   {
     ]b4_tname[
   };
-#endif
 
-#if YYDEBUG
+]b4_token_table_if([[#if YYDEBUG]])[
   /* YYRHS -- A `-1'-separated list of the rules' RHS.  */
   const ]b4_parser_class_name[::rhs_number_type
   ]b4_parser_class_name[::yyrhs_[] =

data/yacc.c

@@ -336,11 +336,6 @@ m4_if(b4_prefix, [yy], [],
 # define YYERROR_VERBOSE ]b4_error_verbose_flag[
 #endif
 
-/* Enabling the token table.  */
-#ifndef YYTOKEN_TABLE
-# define YYTOKEN_TABLE ]b4_token_table[
-#endif
-
 /* In a future release of Bison, this section will be replaced
    by #include "@basename(]b4_spec_defines_file[@)".  */
 ]b4_shared_declarations[
@@ -607,7 +602,7 @@ static const ]b4_int_type_for([b4_rline])[ yyrline[] =
 };
 #endif
 
-#if YYDEBUG || YYERROR_VERBOSE || YYTOKEN_TABLE
+#if YYDEBUG || YYERROR_VERBOSE || ]b4_token_table_flag[
 /* YYTNAME[SYMBOL-NUM] -- String name of the symbol SYMBOL-NUM.
    First, the terminals, then, starting at YYNTOKENS, nonterminals.  */
 static const char *const yytname[] =