X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/22b081deb7ab1d0ec7a279e5213fa7fdc2c85207..9e87ff54729e4d16d61b00b8338a516124ff094d:/data/bison.m4

diff --git a/data/bison.m4 b/data/bison.m4
index 37bc012f..ca27159c 100644
--- a/data/bison.m4
+++ b/data/bison.m4
@@ -2,7 +2,7 @@
 
 # Language-independent M4 Macros for Bison.
 
-# Copyright (C) 2002, 2004-2012 Free Software Foundation, Inc.
+# Copyright (C) 2002, 2004-2013 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
@@ -61,6 +61,44 @@ This special exception was added by the Free Software Foundation in
 version 2.2 of Bison.])])
 
 
+## -------- ##
+## Output.  ##
+## -------- ##
+
+# b4_output_begin(FILE)
+# ---------------------
+# Enable output, i.e., send to diversion 0, expand after "#", and
+# generate the tag to output into FILE.  Must be followed by EOL.
+m4_define([b4_output_begin],
+[m4_changecom()
+m4_divert_push(0)dnl
+@output(m4_unquote([$1])@)@dnl
+])
+
+
+# b4_output_end()
+# ---------------
+# Output nothing, restore # as comment character (no expansions after #).
+m4_define([b4_output_end],
+[m4_divert_pop(0)
+m4_changecom([#])
+])
+
+
+# b4_divert_kill(CODE)
+# --------------------
+# Expand CODE for its side effects, discard its output.
+m4_define([b4_divert_kill],
+[m4_divert_text([KILL], [$1])])
+
+
+# b4_define_silent(MACRO, CODE)
+# -----------------------------
+# Same as m4_define, but throw away the expansion of CODE.
+m4_define([b4_define_silent],
+[m4_define([$1], [b4_divert_kill([$2])])])
+
+
 ## ---------------- ##
 ## Error handling.  ##
 ## ---------------- ##
@@ -82,30 +120,16 @@ _m4eof
 ])dnl
 m4_if(m4_sysval, [0], [], [m4_fatal([$0: cannot write to stdout])])])
 
-# b4_error(KIND, FORMAT, [ARG1], [ARG2], ...)
-# -------------------------------------------
-# Write @KIND(FORMAT@,ARG1@,ARG2@,...@) to stdout.
+# b4_error(KIND, START, END, FORMAT, [ARG1], [ARG2], ...)
+# -------------------------------------------------------
+# Write @KIND(START@,END@,FORMAT@,ARG1@,ARG2@,...@) to stdout.
 #
 # For example:
 #
-#   b4_error([[warn]], [[invalid value for '%s': %s]], [[foo]], [[3]])
+#   b4_error([[complain]], [[input.y:2.3]], [[input.y:5.4]],
+#            [[invalid %s]], [[foo]])
 m4_define([b4_error],
-[b4_cat([[@]$1[(]$2[]]dnl
-[m4_if([$#], [2], [],
-       [m4_foreach([b4_arg],
-                   m4_dquote(m4_shift(m4_shift($@))),
-                   [[@,]b4_arg])])[@)]])])
-
-# b4_error_at(KIND, START, END, FORMAT, [ARG1], [ARG2], ...)
-# ----------------------------------------------------------
-# Write @KIND_at(START@,END@,FORMAT@,ARG1@,ARG2@,...@) to stdout.
-#
-# For example:
-#
-#   b4_error_at([[complain]], [[input.y:2.3]], [[input.y:5.4]],
-#               [[invalid %s]], [[foo]])
-m4_define([b4_error_at],
-[b4_cat([[@]$1[_at(]$2[@,]$3[@,]$4[]]dnl
+[b4_cat([[@complain][(]$1[@,]$2[@,]$3[@,]$4[]]dnl
 [m4_if([$#], [4], [],
        [m4_foreach([b4_arg],
                    m4_dquote(m4_shift(m4_shift(m4_shift(m4_shift($@))))),
@@ -125,21 +149,21 @@ m4_define([b4_error_at],
 #   m4_define([asdf], [ASDF])
 #   m4_define([fsa], [FSA])
 #   m4_define([fdsa], [FDSA])
-#   b4_warn([[[asdf), asdf]]], [[[fsa), fsa]]], [[[fdsa), fdsa]]])
-#   b4_warn([[asdf), asdf]], [[fsa), fsa]], [[fdsa), fdsa]])
-#   b4_warn()
-#   b4_warn(1)
-#   b4_warn(1, 2)
+#   b4_warn_at([[[asdf), asdf]]], [[[fsa), fsa]]], [[[fdsa), fdsa]]])
+#   b4_warn_at([[asdf), asdf]], [[fsa), fsa]], [[fdsa), fdsa]])
+#   b4_warn_at()
+#   b4_warn_at(1)
+#   b4_warn_at(1, 2)
 #
 # Should produce this without newlines:
 #
-#   @warn([asdf), asdf]@,[fsa), fsa]@,[fdsa), fdsa]@)
-#   @warn(asdf), asdf@,fsa), fsa@,fdsa), fdsa@)
+#   @warn_at([asdf), asdf]@,@,@,[fsa), fsa]@,[fdsa), fdsa]@)
+#   @warn(asdf), asdf@,@,@,fsa), fsa@,fdsa), fdsa@)
 #   @warn(@)
 #   @warn(1@)
 #   @warn(1@,2@)
 m4_define([b4_warn],
-[b4_error([[warn]], $@)])
+[b4_error([[warn]], [], [], $@)])
 
 # b4_warn_at(START, END, FORMAT, [ARG1], [ARG2], ...)
 # ---------------------------------------------------
@@ -149,15 +173,15 @@ m4_define([b4_warn],
 #
 #   b4_warn_at([[input.y:2.3]], [[input.y:5.4]], [[invalid %s]], [[foo]])
 m4_define([b4_warn_at],
-[b4_error_at([[warn]], $@)])
+[b4_error([[warn]], $@)])
 
 # b4_complain(FORMAT, [ARG1], [ARG2], ...)
 # ----------------------------------------
-# Write @complain(FORMAT@,ARG1@,ARG2@,...@) to stdout.
+# Bounce to b4_complain_at.
 #
 # See b4_warn example.
 m4_define([b4_complain],
-[b4_error([[complain]], $@)])
+[b4_error([[complain]], [], [], $@)])
 
 # b4_complain_at(START, END, FORMAT, [ARG1], [ARG2], ...)
 # -------------------------------------------------------
@@ -165,15 +189,15 @@ m4_define([b4_complain],
 #
 # See b4_warn_at example.
 m4_define([b4_complain_at],
-[b4_error_at([[complain]], $@)])
+[b4_error([[complain]], $@)])
 
 # b4_fatal(FORMAT, [ARG1], [ARG2], ...)
 # -------------------------------------
-# Write @fatal(FORMAT@,ARG1@,ARG2@,...@) to stdout and exit.
+# Bounce to b4_fatal_at.
 #
 # See b4_warn example.
 m4_define([b4_fatal],
-[b4_error([[fatal]], $@)dnl
+[b4_error([[fatal]], [], [], $@)dnl
 m4_exit(1)])
 
 # b4_fatal_at(START, END, FORMAT, [ARG1], [ARG2], ...)
@@ -182,25 +206,10 @@ m4_exit(1)])
 #
 # See b4_warn_at example.
 m4_define([b4_fatal_at],
-[b4_error_at([[fatal]], $@)dnl
+[b4_error([[fatal]], $@)dnl
 m4_exit(1)])
 
 
-## ---------------- ##
-## Default values.  ##
-## ---------------- ##
-
-# m4_define_default([b4_lex_param], [])   dnl breaks other skeletons
-m4_define_default([b4_pre_prologue], [])
-m4_define_default([b4_post_prologue], [])
-m4_define_default([b4_epilogue], [])
-m4_define_default([b4_parse_param], [])
-
-# The initial column and line.
-m4_define_default([b4_location_initial_column], [1])
-m4_define_default([b4_location_initial_line],   [1])
-
-
 ## ------------ ##
 ## Data Types.  ##
 ## ------------ ##
@@ -221,23 +230,23 @@ m4_define([b4_subtract],
            [m4_eval([$1 - $2])],
            [($1) - ($2)])])
 
-# b4_args(ARG1, ...)
-# _b4_args(ARG1, ...)
+# b4_join(ARG1, ...)
+# _b4_join(ARG1, ...)
 # -------------------
 # Join with comma, skipping empty arguments.
-# b4_args calls itself recursively until it sees the first non-empty
-# argument, then calls _b4_args which prepends each non-empty argument
+# b4_join calls itself recursively until it sees the first non-empty
+# argument, then calls _b4_join which prepends each non-empty argument
 # with a comma.
-m4_define([b4_args],
+m4_define([b4_join],
 [m4_if([$#$1],
        [1], [],
        [m4_ifval([$1],
                  [$1[]_$0(m4_shift($@))],
                  [$0(m4_shift($@))])])])
 
-# _b4_args(ARGS1, ...)
+# _b4_join(ARGS1, ...)
 # --------------------
-m4_define([_b4_args],
+m4_define([_b4_join],
 [m4_if([$#$1],
        [1], [],
        [m4_ifval([$1], [, $1])[]$0(m4_shift($@))])])
@@ -255,30 +264,30 @@ m4_define([b4_integral_parser_tables_map],
 STATE-NUM.]])
 
 $1([defact], [b4_defact],
-   [[YYDEFACT[S] -- default reduction number in state S.  Performed when
-YYTABLE does not specify something else to do.  Zero means the default
-is an error.]])
+   [[YYDEFACT[STATE-NUM] -- Default reduction number in state STATE-NUM.
+Performed when YYTABLE does not specify something else to do.  Zero
+means the default is an error.]])
 
 $1([pgoto], [b4_pgoto], [[YYPGOTO[NTERM-NUM].]])
 
 $1([defgoto], [b4_defgoto], [[YYDEFGOTO[NTERM-NUM].]])
 
 $1([table], [b4_table],
-   [[YYTABLE[YYPACT[STATE-NUM]].  What to do in state STATE-NUM.  If
-positive, shift that token.  If negative, reduce the rule which
+   [[YYTABLE[YYPACT[STATE-NUM]] -- What to do in state STATE-NUM.  If
+positive, shift that token.  If negative, reduce the rule whose
 number is the opposite.  If YYTABLE_NINF, syntax error.]])
 
 $1([check], [b4_check])
 
 $1([stos], [b4_stos],
-   [[STOS_[STATE-NUM] -- The (internal number of the) accessing
+   [[YYSTOS[STATE-NUM] -- The (internal number of the) accessing
 symbol of state STATE-NUM.]])
 
 $1([r1], [b4_r1],
    [[YYR1[YYN] -- Symbol number of symbol that rule YYN derives.]])
 
 $1([r2], [b4_r2],
-   [[YYR2[YYN] -- Number of symbols composing right hand side of rule YYN.]])
+   [[YYR2[YYN] -- Number of symbols on the right hand side of rule YYN.]])
 ])
 
 
@@ -305,7 +314,7 @@ m4_define([b4_flag_if],
 [m4_case(b4_$1_flag,
          [0], [$3],
          [1], [$2],
-         [m4_fatal([invalid $1 value: ]$1)])])
+         [m4_fatal([invalid $1 value: ]b4_$1_flag)])])
 
 
 # b4_define_flag_if(FLAG)
@@ -317,9 +326,9 @@ 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
@@ -333,6 +342,7 @@ m4_define([b4_$3_if],
 b4_define_flag_if([defines])            # Whether headers are requested.
 b4_define_flag_if([glr])                # Whether a GLR parser is requested.
 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.
 
 
@@ -340,6 +350,45 @@ b4_define_flag_if([yacc])               # Whether POSIX Yacc is emulated.
 ## Symbols.  ##
 ## --------- ##
 
+# In order to unify the handling of the various aspects of symbols
+# (tag, type_name, whether terminal, etc.), bison.exe defines one
+# macro per (token, field), where field can has_id, id, etc.: see
+# src/output.c:prepare_symbols_definitions().
+#
+# The various FIELDS are:
+#
+# - has_id: 0 or 1.
+#   Whether the symbol has an id.
+# - id: string
+#   If has_id, the id.  Guaranteed to be usable as a C identifier.
+#   Prefixed by api.token.prefix if defined.
+# - tag: string.
+#   A representat of the symbol.  Can be 'foo', 'foo.id', '"foo"' etc.
+# - user_number: integer
+#   The assigned (external) number as used by yylex.
+# - is_token: 0 or 1
+#   Whether this is a terminal symbol.
+# - number: integer
+#   The internalized number (used after yytranslate).
+# - has_type: 0, 1
+#   Whether has a semantic value.
+# - type_tag: string
+#   When api.value.type=union, the generated name for the union member.
+#   yytype_INT etc. for symbols that has_id, otherwise yytype_1 etc.
+# - type
+#   If it has a semantic value, its type tag, or, if variant are used,
+#   its type.
+#   In the case of api.value.type=union, type is the real type (e.g. int).
+# - has_printer: 0, 1
+# - printer: string
+# - printer_file: string
+# - printer_line: integer
+#   If the symbol has a printer, everything about it.
+# - has_destructor, destructor, destructor_file, destructor_line
+#   Likewise.
+#
+# The following macros provide access to these values.
+
 # b4_symbol_(NUM, FIELD)
 # ----------------------
 # Recover a FIELD about symbol #NUM.  Thanks to m4_indir, fails if
@@ -351,10 +400,10 @@ m4_define([b4_symbol_],
 # b4_symbol(NUM, FIELD)
 # ---------------------
 # Recover a FIELD about symbol #NUM.  Thanks to m4_indir, fails if
-# undefined.  If FIELD = id, prepend the prefix.
+# undefined.  If FIELD = id, prepend the token prefix.
 m4_define([b4_symbol],
 [m4_case([$2],
-         [id],    [m4_do([b4_percent_define_get([api.tokens.prefix])],
+         [id],    [m4_do([b4_percent_define_get([api.token.prefix])],
                          [b4_symbol_([$1], [id])])],
          [b4_symbol_($@)])])
 
@@ -370,6 +419,14 @@ m4_define([b4_symbol_if],
          [m4_fatal([$0: field $2 of $1 is not a Boolean:] b4_symbol([$1], [$2]))])])
 
 
+# b4_symbol_tag_comment(SYMBOL-NUM)
+# ---------------------------------
+# Issue a comment giving the tag of symbol NUM.
+m4_define([b4_symbol_tag_comment],
+[b4_comment([b4_symbol([$1], [tag])])
+])
+
+
 # b4_symbol_action_location(SYMBOL-NUM, KIND)
 # -------------------------------------------
 # Report the location of the KIND action as FILE:LINE.
@@ -383,19 +440,17 @@ m4_define([b4_symbol_action_location],
 # Same as in C, but using references instead of pointers.
 m4_define([b4_symbol_action],
 [b4_symbol_if([$1], [has_$2],
-[m4_pushdef([b4_dollar_dollar],
-    [b4_symbol_value([(*yyvaluep)],
-                     b4_symbol_if([$1], [has_type],
-                                  [b4_symbol([$1], [type])]))])dnl
-m4_pushdef([b4_at_dollar], [(*yylocationp)])dnl
-      b4_symbol_case_([$1])
+[b4_dollar_pushdef([(*yyvaluep)],
+                   b4_symbol_if([$1], [has_type],
+                                [m4_dquote(b4_symbol([$1], [type]))]),
+                   [(*yylocationp)])dnl
+    b4_symbol_case_([$1])[]dnl
 b4_syncline([b4_symbol([$1], [$2_line])], ["b4_symbol([$1], [$2_file])"])
-        b4_symbol([$1], [$2])
+      b4_symbol([$1], [$2])
 b4_syncline([@oline@], [@ofile@])
         break;
 
-m4_popdef([b4_at_dollar])dnl
-m4_popdef([b4_dollar_dollar])dnl
+b4_dollar_popdef[]dnl
 ])])
 
 
@@ -406,11 +461,29 @@ m4_define([b4_symbol_destructor], [b4_symbol_action([$1], [destructor])])
 m4_define([b4_symbol_printer],    [b4_symbol_action([$1], [printer])])
 
 
+# b4_symbol_actions(KIND, [TYPE = yytype])
+# ----------------------------------------
+# Emit the symbol actions for KIND ("printer" or "destructor").
+# Dispatch on TYPE.
+m4_define([b4_symbol_actions],
+[m4_pushdef([b4_actions_], m4_expand([b4_symbol_foreach([b4_symbol_$1])]))dnl
+m4_ifval(m4_defn([b4_actions_]),
+[switch (m4_default([$2], [yytype]))
+    {
+      m4_defn([b4_actions_])
+      default:
+        break;
+    }dnl
+],
+[YYUSE (m4_default([$2], [yytype]));])dnl
+m4_popdef([b4_actions_])dnl
+])
+
 # b4_symbol_case_(SYMBOL-NUM)
 # ---------------------------
 # Issue a "case NUM" for SYMBOL-NUM.
 m4_define([b4_symbol_case_],
-[      case b4_symbol([$1], [number]): // b4_symbol([$1], [tag])
+[case b4_symbol([$1], [number]): b4_symbol_tag_comment([$1])])
 ])
 
 
@@ -420,6 +493,45 @@ m4_define([b4_symbol_case_],
 m4_define([b4_symbol_foreach],
           [m4_map([$1], m4_defn([b4_symbol_numbers]))])
 
+# b4_symbol_map(MACRO)
+# --------------------
+# Return a list (possibly empty elements) of MACRO invoked for each
+# SYMBOL-NUM.
+m4_define([b4_symbol_map],
+[m4_map_args_sep([$1(], [)], [,], b4_symbol_numbers)])
+
+
+# b4_token_visible_if(NUM, IF-TRUE, IF-FALSE)
+# -------------------------------------------
+# Whether NUM denotes a token that has an exported definition (i.e.,
+# shows in enum yytokentype).
+m4_define([b4_token_visible_if],
+[b4_symbol_if([$1], [is_token],
+              [b4_symbol_if([$1], [has_id], [$2], [$3])],
+              [$3])])
+
+# b4_token_has_definition(NUM)
+# ----------------------------
+# 1 if NUM is visible, nothing otherwise.
+m4_define([b4_token_has_definition],
+[b4_token_visible_if([$1], [1])])
+
+# b4_any_token_visible_if([IF-TRUE], [IF-FALSE])
+# ----------------------------------------------
+# Whether there is a token that needs to be defined.
+m4_define([b4_any_token_visible_if],
+[m4_ifval(b4_symbol_foreach([b4_token_has_definition]),
+          [$1], [$2])])
+
+
+# b4_token_format(FORMAT, NUM)
+# ----------------------------
+m4_define([b4_token_format],
+[b4_token_visible_if([$2],
+[m4_quote(m4_format([$1],
+                     [b4_symbol([$2], [id])],
+                     [b4_symbol([$2], [user_number])]))])])
+
 
 ## ------- ##
 ## Types.  ##
@@ -429,9 +541,12 @@ m4_define([b4_symbol_foreach],
 # ---------------------
 # Run actions for the symbol NUMS that all have the same type-name.
 # Skip NUMS that have no type-name.
+#
+# To specify the action to run, define b4_dollar_dollar(NUMBER,
+# TAG, TYPE).
 m4_define([b4_type_action_],
 [b4_symbol_if([$1], [has_type],
-[m4_map([b4_symbol_case_], [$@])[]dnl
+[m4_map([      b4_symbol_case_], [$@])[]dnl
         b4_dollar_dollar([b4_symbol([$1], [number])],
                          [b4_symbol([$1], [tag])],
                          [b4_symbol([$1], [type])]);
@@ -463,11 +578,21 @@ m4_define([b4_basename],
 # -----------------------
 m4_define([b4_syncline],
 [b4_flag_if([synclines],
-[b4_sync_end([__line__], [b4_basename(m4_quote(__file__))])
-b4_sync_start([$1], [$2])])])
+[b4_sync_start([$1], [$2]) b4_sync_end([__line__],
+                                       [b4_basename(m4_quote(__file__))])[]dnl
+])])
+
+# b4_sync_start(LINE, FILE)
+# -----------------------
+# Syncline for the new place.  Typically a directive for the compiler.
+m4_define([b4_sync_start], [b4_comment([$2:$1])])
+
+# b4_sync_end(LINE, FILE)
+# -----------------------
+# Syncline for the current place, which ends.  Typically a comment
+# left for the reader.
+m4_define([b4_sync_end],   [b4_comment([$2:$1])])
 
-m4_define([b4_sync_end], [b4_comment([Line $1 of $2])])
-m4_define([b4_sync_start], [b4_comment([Line $1 of $2])])
 
 # b4_user_code(USER-CODE)
 # -----------------------
@@ -489,14 +614,14 @@ m4_define([b4_define_user_code],
 # b4_user_initial_action
 # b4_user_post_prologue
 # b4_user_pre_prologue
-# b4_user_stype
+# b4_user_union_members
 # ----------------------
 # Macros that issue user code, ending with synclines.
 b4_define_user_code([actions])
 b4_define_user_code([initial_action])
 b4_define_user_code([post_prologue])
 b4_define_user_code([pre_prologue])
-b4_define_user_code([stype])
+b4_define_user_code([union_members])
 
 
 # b4_check_user_names(WHAT, USER-LIST, BISON-NAMESPACE)
@@ -577,9 +702,9 @@ m4_define([b4_percent_define_use],
 #   b4_percent_define_get([[foo]])
 m4_define([b4_percent_define_get],
 [b4_percent_define_use([$1])dnl
-m4_ifdef([b4_percent_define(]$1[)],
-         [m4_indir([b4_percent_define(]$1[)])],
-         [$2])])
+b4_percent_define_ifdef_([$1],
+                         [m4_indir([b4_percent_define(]$1[)])],
+                         [$2])])
 
 # b4_percent_define_get_loc(VARIABLE)
 # -----------------------------------
@@ -598,7 +723,21 @@ m4_define([b4_percent_define_get_loc],
           [m4_pushdef([b4_loc], m4_indir([b4_percent_define_loc(]$1[)]))dnl
 b4_loc[]dnl
 m4_popdef([b4_loc])],
-          [b4_fatal([[b4_percent_define_get_loc: undefined %%define variable '%s']], [$1])])])
+          [b4_fatal([[$0: undefined %%define variable '%s']], [$1])])])
+
+# b4_percent_define_get_kind(VARIABLE)
+# ------------------------------------
+# Get the kind (code, keyword, string) of VARIABLE, i.e., how its
+# value was defined (braces, not delimiters, quotes).
+#
+# If the %define variable VARIABLE is undefined, complain fatally
+# since that's a Bison or skeleton error.  Don't record this as a
+# Bison usage of VARIABLE as there's no reason to suspect that the
+# user-supplied value has yet influenced the output.
+m4_define([b4_percent_define_get_kind],
+[m4_ifdef([b4_percent_define_kind(]$1[)],
+          [m4_indir([b4_percent_define_kind(]$1[)])],
+          [b4_fatal([[$0: undefined %%define variable '%s']], [$1])])])
 
 # b4_percent_define_get_syncline(VARIABLE)
 # ----------------------------------------
@@ -615,7 +754,20 @@ m4_popdef([b4_loc])],
 m4_define([b4_percent_define_get_syncline],
 [m4_ifdef([b4_percent_define_syncline(]$1[)],
           [m4_indir([b4_percent_define_syncline(]$1[)])],
-          [b4_fatal([[b4_percent_define_get_syncline: undefined %%define variable '%s']], [$1])])])
+          [b4_fatal([[$0: undefined %%define variable '%s']], [$1])])])
+
+# b4_percent_define_ifdef_(VARIABLE, IF-TRUE, [IF-FALSE])
+# ------------------------------------------------------
+# If the %define variable VARIABLE is defined, expand IF-TRUE, else expand
+# IF-FALSE.  Don't record usage of VARIABLE.
+#
+# For example:
+#
+#   b4_percent_define_ifdef_([[foo]], [[it's defined]], [[it's undefined]])
+m4_define([b4_percent_define_ifdef_],
+[m4_ifdef([b4_percent_define(]$1[)],
+          [$2],
+          [$3])])
 
 # b4_percent_define_ifdef(VARIABLE, IF-TRUE, [IF-FALSE])
 # ------------------------------------------------------
@@ -628,9 +780,9 @@ m4_define([b4_percent_define_get_syncline],
 #
 #   b4_percent_define_ifdef([[foo]], [[it's defined]], [[it's undefined]])
 m4_define([b4_percent_define_ifdef],
-[m4_ifdef([b4_percent_define(]$1[)],
-          [b4_percent_define_use([$1])$2],
-          [$3])])
+[b4_percent_define_ifdef_([$1],
+                         [b4_percent_define_use([$1])$2],
+                         [$3])])
 
 
 ## --------- ##
@@ -659,11 +811,11 @@ m4_define([b4_percent_define_flag_if],
                                            [[invalid value for %%define Boolean variable '%s']],
                                            [$1])],
                            [[b4_percent_define_flag_if($1)]])])],
-  [b4_fatal([[b4_percent_define_flag_if: undefined %%define variable '%s']], [$1])])])
+  [b4_fatal([[$0: undefined %%define variable '%s']], [$1])])])
 
 
-# b4_percent_define_default(VARIABLE, DEFAULT)
-# --------------------------------------------
+# b4_percent_define_default(VARIABLE, DEFAULT, [KIND = keyword])
+# --------------------------------------------------------------
 # Mimic muscle_percent_define_default in ../src/muscle-tab.h exactly.  That is,
 # if the %define variable VARIABLE is undefined, set its value to DEFAULT.
 # Don't record this as a Bison usage of VARIABLE as there's no reason to
@@ -673,25 +825,43 @@ m4_define([b4_percent_define_flag_if],
 #
 #   b4_percent_define_default([[foo]], [[default value]])
 m4_define([b4_percent_define_default],
-[m4_ifndef([b4_percent_define(]$1[)],
+[b4_percent_define_ifdef_([$1], [],
            [m4_define([b4_percent_define(]$1[)], [$2])dnl
+            m4_define([b4_percent_define_kind(]$1[)],
+                      [m4_default([$3], [keyword])])dnl
             m4_define([b4_percent_define_loc(]$1[)],
                       [[[[<skeleton default value>:-1.-1]],
                         [[<skeleton default value>:-1.-1]]]])dnl
             m4_define([b4_percent_define_syncline(]$1[)], [[]])])])
 
 
-# b4_percent_define_if_define(VARIABLE)
-# -------------------------------------
-# Define b4_VARIABLE_if that executes its $1 or $2 depending whether
-# VARIABLE was %defined.  The characters `.' and `-' in VARIABLE are mapped
-# to `_'.
+# b4_percent_define_if_define(NAME, [VARIABLE = NAME])
+# ----------------------------------------------------
+# Define b4_NAME_if that executes its $1 or $2 depending whether
+# VARIABLE was %defined.  The characters '.' and `-' in VARIABLE are mapped
+# to '_'.
 m4_define([b4_percent_define_if_define_],
 [m4_define(m4_bpatsubst([b4_$1_if], [[-.]], [_]),
-           [b4_percent_define_flag_if([$1], [$2], [$3])])])
+           [b4_percent_define_flag_if(m4_default([$2], [$1]),
+                                      [$3], [$4])])])
 m4_define([b4_percent_define_if_define],
-[b4_percent_define_default([[$1]], [[false]])
-b4_percent_define_if_define_([$1], $[1], $[2])])
+[b4_percent_define_default([m4_default([$2], [$1])], [[false]])
+b4_percent_define_if_define_([$1], [$2], $[1], $[2])])
+
+
+# b4_percent_define_check_kind(VARIABLE, KIND, [DIAGNOSTIC = complain])
+# ---------------------------------------------------------------------
+m4_define([b4_percent_define_check_kind],
+[b4_percent_define_ifdef_([$1],
+  [m4_if(b4_percent_define_get_kind([$1]), [$2], [],
+    [b4_error([m4_default([$3], [complain])],
+              b4_percent_define_get_loc([$1]),
+              [m4_case([$2],
+                 [code], [[%%define variable '%s' requires '{...}' values]],
+                 [keyword], [[%%define variable '%s' requires keyword values]],
+                 [string], [[%%define variable '%s' requires '"..."' values]])],
+              [$1])])])dnl
+])
 
 
 # b4_percent_define_check_values(VALUES)
@@ -715,8 +885,9 @@ m4_define([b4_percent_define_check_values],
             [_b4_percent_define_check_values(b4_sublist)])])
 
 m4_define([_b4_percent_define_check_values],
-[m4_ifdef([b4_percent_define(]$1[)],
-  [m4_pushdef([b4_good_value], [0])dnl
+[b4_percent_define_ifdef_([$1],
+  [b4_percent_define_check_kind(]$1[, [keyword], [deprecated])dnl
+   m4_pushdef([b4_good_value], [0])dnl
    m4_if($#, 1, [],
          [m4_foreach([b4_value], m4_dquote(m4_shift($@)),
                      [m4_if(m4_indir([b4_percent_define(]$1[)]), b4_value,
@@ -727,11 +898,11 @@ m4_define([_b4_percent_define_check_values],
                          [$1],
                          m4_dquote(m4_indir([b4_percent_define(]$1[)])))
           m4_foreach([b4_value], m4_dquote(m4_shift($@)),
-                     [b4_complain_at(b4_percent_define_get_loc([$1]),
+                     [b4_error([[note]], b4_percent_define_get_loc([$1]), []
                                      [[accepted value: '%s']],
                                      m4_dquote(b4_value))])])dnl
    m4_popdef([b4_good_value])],
-  [b4_fatal([[b4_percent_define_check_values: undefined %%define variable '%s']], [$1])])])
+  [b4_fatal([[$0: undefined %%define variable '%s']], [$1])])])
 
 # b4_percent_code_get([QUALIFIER])
 # --------------------------------
@@ -772,21 +943,23 @@ m4_define([b4_percent_code_ifdef],
 ## Common variables.  ##
 ## ------------------ ##
 
-# Default values for %define.
-# ---------------------------
-# If the api.tokens.prefix, it is empty.
-m4_percent_define_default([[api.tokens.prefix]], [[]])
 
 # b4_parse_assert_if([IF-ASSERTIONS-ARE-USED], [IF-NOT])
 # b4_parse_trace_if([IF-DEBUG-TRACES-ARE-ENABLED], [IF-NOT])
-# b4_lex_symbol_if([IF-YYLEX-RETURNS-A-COMPLETE-SYMBOL], [IF-NOT])
-# b4_variant_if([IF-VARIANT-ARE-USED], [IF-NOT])
+# b4_token_ctor_if([IF-YYLEX-RETURNS-A-TOKEN], [IF-NOT])
 # ----------------------------------------------
-b4_percent_define_if_define([lex_symbol])
+b4_percent_define_if_define([token_ctor], [api.token.constructor])
 b4_percent_define_if_define([locations])     # Whether locations are tracked.
 b4_percent_define_if_define([parse.assert])
 b4_percent_define_if_define([parse.trace])
-b4_percent_define_if_define([variant])
+
+
+# b4_bison_locations_if([IF-TRUE])
+# --------------------------------
+# Expand IF-TRUE if using locations, and using the default location
+# type.
+m4_define([b4_bison_locations_if],
+[b4_locations_if([b4_percent_define_ifdef([[api.location.type]], [], [$1])])])
 
 
 # b4_error_verbose_if([IF-ERRORS-ARE-VERBOSE], [IF-NOT])
@@ -802,6 +975,20 @@ m4_define([b4_error_verbose_flag],
                    [verbose], [[1]])])
 b4_define_flag_if([error_verbose])
 
+# yytoken_table is needed to support verbose errors.
+b4_error_verbose_if([m4_define([b4_token_table_flag], [1])])
+
+
+# b4_variant_if([IF-VARIANT-ARE-USED], [IF-NOT])
+# ----------------------------------------------
+b4_percent_define_if_define([variant])
+m4_define([b4_variant_flag], [[0]])
+b4_percent_define_ifdef([[api.value.type]],
+   [m4_case(b4_percent_define_get_kind([[api.value.type]]), [keyword],
+            [m4_case(b4_percent_define_get([[api.value.type]]), [variant],
+                    [m4_define([b4_variant_flag], [[1]])])])])
+b4_define_flag_if([variant])
+
 
 ## ----------------------------------------------------------- ##
 ## After processing the skeletons, check that all the user's   ##
@@ -818,3 +1005,59 @@ m4_wrap_lifo([
 b4_check_user_names_wrap([[define]], [[variable]])
 b4_check_user_names_wrap([[code]], [[qualifier]])
 ])
+
+
+## ---------------- ##
+## Default values.  ##
+## ---------------- ##
+
+# m4_define_default([b4_lex_param], [])   dnl breaks other skeletons
+m4_define_default([b4_pre_prologue], [])
+m4_define_default([b4_post_prologue], [])
+m4_define_default([b4_epilogue], [])
+m4_define_default([b4_parse_param], [])
+
+# The initial column and line.
+m4_define_default([b4_location_initial_column], [1])
+m4_define_default([b4_location_initial_line],   [1])
+
+
+## --------------- ##
+## Sanity checks.  ##
+## --------------- ##
+
+# api.location.prefix={...} (Java and C++).
+b4_percent_define_check_kind([api.location.type], [code], [deprecated])
+
+# api.position.prefix={...} (Java).
+b4_percent_define_check_kind([api.position.type], [code], [deprecated])
+
+# api.prefix >< %name-prefix.
+b4_percent_define_check_kind([api.prefix], [code], [deprecated])
+b4_percent_define_ifdef([api.prefix],
+[m4_ifdef([b4_prefix],
+[b4_complain_at(b4_percent_define_get_loc([api.prefix]),
+                [['%s' and '%s' cannot be used together]],
+                [%name-prefix],
+                [%define api.prefix])])])
+
+# api.token.prefix={...}
+# Make it a warning for those who used betas of Bison 3.0.
+b4_percent_define_check_kind([api.token.prefix], [code], [deprecated])
+
+# api.value.type >< %union.
+b4_percent_define_ifdef([api.value.type],
+[m4_ifdef([b4_union_members],
+[b4_complain_at(b4_percent_define_get_loc([api.value.type]),
+                [['%s' and '%s' cannot be used together]],
+                [%union],
+                [%define api.value.type])])])
+
+# api.value.type=union >< %yacc.
+b4_percent_define_ifdef([api.value.type],
+[m4_if(b4_percent_define_get([api.value.type]), [union],
+[b4_yacc_if(dnl
+[b4_complain_at(b4_percent_define_get_loc([api.value.type]),
+                [['%s' and '%s' cannot be used together]],
+                [%yacc],
+                [%define api.value.type "union"])])])])