* bootstrap (gnulib_modules): Add strverscmp.

* lib/.cvsignore: Add strverscmp.c, strverscmp.h.
* m4/.cvsignore: Add strverscmp.m4.
* src/parse-gram.y (%require): New token, new rule.
(version_check): New.
* src/scan-gram.l (%require): Adjust.
* tests/input.at (AT_REQUIRE): New.
Use it.
* doc/bison.texinfo (Require Decl): New.
(Calc++ Parser): Use %require.

ChangeLog

@@ -1,3 +1,16 @@
+2005-10-02  Akim Demaille  <akim@epita.fr>
+
+	* bootstrap (gnulib_modules): Add strverscmp.
+	* lib/.cvsignore: Add strverscmp.c, strverscmp.h.
+	* m4/.cvsignore: Add strverscmp.m4.
+	* src/parse-gram.y (%require): New token, new rule.
+	(version_check): New.
+	* src/scan-gram.l (%require): Adjust.
+	* tests/input.at (AT_REQUIRE): New.
+	Use it.
+	* doc/bison.texinfo (Require Decl): New.
+	(Calc++ Parser): Use %require.
+
 2005-10-02  Akim Demaille  <akim@epita.fr>
 
 	* data/location.cc: New.

NEWS

@@ -5,6 +5,9 @@ Changes in version 2.1a:
 
 * DJGPP support added.
 
+* %require "VERSION"
+  To specify the youngest version of Bison accepted by the grammar file.
+
 * lalr1.cc: The token and value types are now class members.
   The tokens where defined as free form enums and cpp macros.  YYSTYPE
   was defined as a free form union.  Both are now class members:
@@ -13,8 +16,11 @@ Changes in version 2.1a:
 
   If you do not want or can update to this scheme, the directive
   `%define "global_tokens_and_yystype" "1"' triggers the global
-  definition of tokens and YYSTYPE.
+  definition of tokens and YYSTYPE.  This change is suitable both
+  for previous releases of Bison, and this one.
 
+  If you wish to update, then make sure older version of Bison will
+  fail using `%require "2.1a"'.
 
 Changes in version 2.1, 2005-09-16:
 

bootstrap

@@ -110,6 +110,7 @@ stdio-safer
 stpcpy
 strerror
 strtoul
+strverscmp
 unistd-safer
 verify
 xalloc

doc/bison.texinfo

@@ -145,9 +145,9 @@ The Concepts of Bison
 
 Writing @acronym{GLR} Parsers
 
-* Simple GLR Parsers::          Using @acronym{GLR} parsers on unambiguous grammars
-* Merging GLR Parses::          Using @acronym{GLR} parsers to resolve ambiguities
-* Compiler Requirements::       @acronym{GLR} parsers require a modern C compiler
+* Simple GLR Parsers::       Using @acronym{GLR} parsers on unambiguous grammars
+* Merging GLR Parses::       Using @acronym{GLR} parsers to resolve ambiguities
+* Compiler Requirements::    @acronym{GLR} parsers require a modern C compiler
 
 Examples
 
@@ -225,6 +225,7 @@ Tracking Locations
 
 Bison Declarations
 
+* Require Decl::      Requiring a Bison version.
 * Token Decl::        Declaring terminal symbols.
 * Precedence Decl::   Declaring terminals with precedence and associativity.
 * Union Decl::        Declaring the set of all semantic value types.
@@ -732,9 +733,9 @@ user-defined function on the resulting values to produce an arbitrary
 merged result.
 
 @menu
-* Simple GLR Parsers::          Using @acronym{GLR} parsers on unambiguous grammars
-* Merging GLR Parses::          Using @acronym{GLR} parsers to resolve ambiguities
-* Compiler Requirements::       @acronym{GLR} parsers require a modern C compiler
+* Simple GLR Parsers::       Using @acronym{GLR} parsers on unambiguous grammars
+* Merging GLR Parses::       Using @acronym{GLR} parsers to resolve ambiguities
+* Compiler Requirements::    @acronym{GLR} parsers require a modern C compiler
 @end menu
 
 @node Simple GLR Parsers
@@ -3548,6 +3549,7 @@ it explicitly (@pxref{Language and Grammar, ,Languages and Context-Free
 Grammars}).
 
 @menu
+* Require Decl::      Requiring a Bison version.
 * Token Decl::        Declaring terminal symbols.
 * Precedence Decl::   Declaring terminals with precedence and associativity.
 * Union Decl::        Declaring the set of all semantic value types.
@@ -3560,6 +3562,19 @@ Grammars}).
 * Decl Summary::      Table of all Bison declarations.
 @end menu
 
+@node Require Decl
+@subsection Require a Version of Bison
+@cindex version requirement
+@cindex requiring a version of Bison
+@findex %require
+
+You may require the minimum version of Bison to process the grammar.  If
+the requirement is not met, @command{bison} exits with an error.
+
+@example
+%require "@var{version}"
+@end example
+
 @node Token Decl
 @subsection Token Type Names
 @cindex declaring token type names
@@ -4157,6 +4172,12 @@ Request a pure (reentrant) parser program (@pxref{Pure Decl, ,A Pure
 (Reentrant) Parser}).
 @end deffn
 
+@deffn {Directive} %require "@var{version}"
+Specify that version @var{version} or higher of Bison required for the
+grammar.
+@xref{Require Decl, , Require a Version of Bison}.
+@end deffn
+
 @deffn {Directive} %token-table
 Generate an array of token names in the parser file.  The name of the
 array is @code{yytname}; @code{yytname[@var{i}]} is the name of the
@@ -7275,13 +7296,16 @@ calcxx_driver::error (const std::string& m)
 @node Calc++ Parser
 @subsection Calc++ Parser
 
-The parser definition file @file{calc++-parser.yy} starts by asking
-for the C++ LALR(1) skeleton, the creation of the parser header file, and
-specifies the name of the parser class.
+The parser definition file @file{calc++-parser.yy} starts by asking for
+the C++ LALR(1) skeleton, the creation of the parser header file, and
+specifies the name of the parser class.  Because the C++ skeleton
+changed several times, it is safer to require the version you designed
+the grammar for.
 
 @comment file: calc++-parser.yy
 @example
 %skeleton "lalr1.cc"                          /*  -*- C++ -*- */
+%require "2.1a"
 %defines
 %define "parser_class_name" "calcxx_parser"
 @end example
@@ -7968,6 +7992,12 @@ Bison declaration to request a pure (reentrant) parser.
 @xref{Pure Decl, ,A Pure (Reentrant) Parser}.
 @end deffn
 
+@deffn {Directive} %require "@var{version}"
+Specify that version @var{version} or higher of Bison required for the
+grammar.
+@xref{Require Decl, , Require a Version of Bison}.
+@end deffn
+
 @deffn {Directive} %right
 Bison declaration to assign right associativity to token(s).
 @xref{Precedence Decl, ,Operator Precedence}.

lib/.cvsignore

@@ -54,6 +54,8 @@ strnlen.c
 strnlen.h
 strtol.c
 strtoul.c
+strverscmp.c
+strverscmp.h
 unistd--.h
 unistd-safer.h
 unlocked-io.h

m4/.cvsignore

@@ -30,6 +30,7 @@ strndup.m4
 strnlen.m4
 strtol.m4
 strtoul.m4
+strverscmp.m4
 unistd-safer.m4
 unlocked-io.m4
 xalloc.m4

src/parse-gram.h

@@ -63,21 +63,22 @@
      PERCENT_OUTPUT = 288,
      PERCENT_PARSE_PARAM = 289,
      PERCENT_PURE_PARSER = 290,
-     PERCENT_SKELETON = 291,
-     PERCENT_START = 292,
-     PERCENT_TOKEN_TABLE = 293,
-     PERCENT_VERBOSE = 294,
-     PERCENT_YACC = 295,
-     TYPE = 296,
-     EQUAL = 297,
-     SEMICOLON = 298,
-     PIPE = 299,
-     ID = 300,
-     ID_COLON = 301,
-     PERCENT_PERCENT = 302,
-     PROLOGUE = 303,
-     EPILOGUE = 304,
-     BRACED_CODE = 305
+     PERCENT_REQUIRE = 291,
+     PERCENT_SKELETON = 292,
+     PERCENT_START = 293,
+     PERCENT_TOKEN_TABLE = 294,
+     PERCENT_VERBOSE = 295,
+     PERCENT_YACC = 296,
+     TYPE = 297,
+     EQUAL = 298,
+     SEMICOLON = 299,
+     PIPE = 300,
+     ID = 301,
+     ID_COLON = 302,
+     PERCENT_PERCENT = 303,
+     PROLOGUE = 304,
+     EPILOGUE = 305,
+     BRACED_CODE = 306
    };
 #endif
 /* Tokens.  */
@@ -115,27 +116,28 @@
 #define PERCENT_OUTPUT 288
 #define PERCENT_PARSE_PARAM 289
 #define PERCENT_PURE_PARSER 290
-#define PERCENT_SKELETON 291
-#define PERCENT_START 292
-#define PERCENT_TOKEN_TABLE 293
-#define PERCENT_VERBOSE 294
-#define PERCENT_YACC 295
-#define TYPE 296
-#define EQUAL 297
-#define SEMICOLON 298
-#define PIPE 299
-#define ID 300
-#define ID_COLON 301
-#define PERCENT_PERCENT 302
-#define PROLOGUE 303
-#define EPILOGUE 304
-#define BRACED_CODE 305
+#define PERCENT_REQUIRE 291
+#define PERCENT_SKELETON 292
+#define PERCENT_START 293
+#define PERCENT_TOKEN_TABLE 294
+#define PERCENT_VERBOSE 295
+#define PERCENT_YACC 296
+#define TYPE 297
+#define EQUAL 298
+#define SEMICOLON 299
+#define PIPE 300
+#define ID 301
+#define ID_COLON 302
+#define PERCENT_PERCENT 303
+#define PROLOGUE 304
+#define EPILOGUE 305
+#define BRACED_CODE 306
 
 
 
 
 #if ! defined (YYSTYPE) && ! defined (YYSTYPE_IS_DECLARED)
-#line 79 "../../src/parse-gram.y"
+#line 82 "../../src/parse-gram.y"
 typedef union YYSTYPE {
   symbol *symbol;
   symbol_list *list;
@@ -145,7 +147,7 @@ typedef union YYSTYPE {
   uniqstr uniqstr;
 } YYSTYPE;
 /* Line 1505 of yacc.c.  */
-#line 149 "../../src/parse-gram.h"
+#line 151 "../../src/parse-gram.h"
 # define yystype YYSTYPE /* obsolescent; will be withdrawn */
 # define YYSTYPE_IS_DECLARED 1
 # define YYSTYPE_IS_TRIVIAL 1

src/parse-gram.y

@@ -32,6 +32,7 @@
 #include "quotearg.h"
 #include "reader.h"
 #include "symlist.h"
+#include "strverscmp.h"
 
 #define YYLLOC_DEFAULT(Current, Rhs, N)  (Current) = lloc_default (Rhs, N)
 static YYLTYPE lloc_default (YYLTYPE const *, int);
@@ -39,6 +40,8 @@ static YYLTYPE lloc_default (YYLTYPE const *, int);
 #define YY_LOCATION_PRINT(File, Loc) \
           location_print (File, Loc)
 
+static void version_check (location const *loc, char const *version);
+
 /* Request detailed syntax error messages, and pass them to GRAM_ERROR.
    FIXME: depends on the undocumented availability of YYLLOC.  */
 #undef  yyerror
@@ -133,6 +136,7 @@ static int current_prec = 0;
   PERCENT_OUTPUT          "%output"
   PERCENT_PARSE_PARAM     "%parse-param {...}"
   PERCENT_PURE_PARSER     "%pure-parser"
+  PERCENT_REQUIRE 	  "%require"
   PERCENT_SKELETON        "%skeleton"
   PERCENT_START           "%start"
   PERCENT_TOKEN_TABLE     "%token-table"
@@ -226,6 +230,7 @@ declaration:
 | "%output" "=" string_content             { spec_outfile = $3; }
 | "%parse-param {...}"			   { add_param ("parse_param", $1, @1); }
 | "%pure-parser"                           { pure_parser = true; }
+| "%require" string_content                { version_check (&@2, $2); }
 | "%skeleton" string_content               { skeleton = $2; }
 | "%token-table"                           { token_table_flag = true; }
 | "%verbose"                               { report_flag = report_states; }
@@ -530,6 +535,14 @@ add_param (char const *type, char *decl, location loc)
   scanner_last_string_free ();
 }
 
+static void
+version_check (location const *loc, char const *version)
+{
+  if (strverscmp (version, PACKAGE_VERSION) > 0)
+    complain_at (*loc, "require bison %s, but have %s",
+		 version, PACKAGE_VERSION);
+}
+
 static void
 gram_error (location const *loc, char const *msg)
 {

src/scan-gram.l

@@ -224,6 +224,7 @@ splice	 (\\[ \f\t\v]*\n)*
   "%prec"                 rule_length--; return PERCENT_PREC;
   "%printer"              token_type = PERCENT_PRINTER; BEGIN SC_PRE_CODE;
   "%pure"[-_]"parser"     return PERCENT_PURE_PARSER;
+  "%require"              return PERCENT_REQUIRE;
   "%right"                return PERCENT_RIGHT;
   "%skeleton"             return PERCENT_SKELETON;
   "%start"                return PERCENT_START;

tests/input.at

@@ -297,3 +297,24 @@ exp: "MY TOKEN";
 AT_CHECK([bison -o input.c input.y])
 
 AT_CLEANUP
+
+
+## --------- ##
+## Require.  ##
+## --------- ##
+
+m4_define([AT_CHECK_REQUIRE],
+[AT_SETUP([Require $1])
+AT_DATA_GRAMMAR([input.y],
+[[%require "$1";
+%%
+empty_file:;
+]])
+AT_CHECK([bison -o input.c input.y], $2, [], ignore)
+AT_CLEANUP
+])
+
+AT_CHECK_REQUIRE(1.0, 0)
+AT_CHECK_REQUIRE(AT_PACKAGE_VERSION, 0)
+## FIXME: Some day augment this version number.
+AT_CHECK_REQUIRE(100.0, 1)