From: "Juan Manuel Guerrero" <ST001906 AT HRZ1 DOT HRZ DOT TU-Darmstadt DOT De>
Organization: Darmstadt University of Technology
To: djgpp AT delorie DOT com
Date: Mon, 6 Dec 1999 11:45:36 +0100
Subject: Support of BISON in AUTOCONF/AUTOMAKE
X-mailer: Pegasus Mail for Windows (v2.54DE)
Message-ID: <944B391AAA@HRZ1.hrz.tu-darmstadt.de>
Reply-To: djgpp AT delorie DOT com

If one inspects the sources of AUTOCONF and AUTOMAKE
one will notice that there is already build-in support
for MSDOS ports of FLEX/LEX.
This support is done in the AC_DECL_YYTEXT macro contained
in file acspecif.m4 and in function: output_lex_build_rule
in file automake.in.
AC_DECL_YYTEXT, apart from all other jobs it does, compiles
a minimal lex program, checks for the output file name and
set the variable @LEX_OUTPUT_ROOT@ to lex.yy or lexyy accordingly.
The function output_lex_build_rule in automake.in creates in makefile.in
the following line:
  LEX_OUTPUT_ROOT = @LEX_OUTPUT_ROOT@
and the implicit rule for flex:
  .l.c:
  	$(SHELL) $(YLWRAP) "$(LEX)" $< $(LEX_OUTPUT_ROOT).c $@ -- $(AM_LFLAGS) $(LFLAGS)
or a similar rule without YLWRAP.
When config.status is executed @LEX_OUTPUT_ROOT@ is replaced by the appropiate value.
All this can be used as a guide line for how to properly implement
support for MSDOS ports of BISON/BYACC.
It should be clear that changes to autoconf AND automake will be needed.


1) AUTOCONF modifications.
The macro AC_PROG_YACC contained in file acspecific.m4 has been
modified to provide the following functionality:
  1: Check for bison, byacc, yacc or issue a "missing" message.
  2: Compile a minimal grammar file and
     check for the output file name.
  3: Set the the new variable to:
     @YACC_TABEXT@ = .tab for BISON ports that
     create file names with multiple dots.
     @YACC_TABEXT@ = _tab for BISON ports that
     do NOT create file names with multiple dots.
The choose of @YACC_TABEXT@ =.tab or_tab instead of
@YACC_OUTPUT_ROOT@ = y.tab ory_tab is not arbitrary.
Choosing the variable @YACC_TABEXT@ instead of @YACC_OUTPUT_ROOT@
allows to cope with the two types of output file name that bison can create:
  1:  y.tab.[ch]    -->  y$(YACC_TABEXT).[ch]
  2:  foo.tab.[ch]  -->  foo$(YACC_TABEXT).[ch]
There is no need to introduce a second variable to cope with the case
that bison is invoked with the file name prefix option (-b).

2) AUTOMAKE modifications.
The modifications needed concern the files automake.in and compile.am
automake.in creates the implicit rule for the grammar files and compile.am
contains the "clean" rule.

The function: output_yacc_build_rule in automake.in has been modified
the following way:
  1: The command line:
         &define_configure_variable ('YACC_TABEXT');
     has been inserted. This command will create in makefile.in
     the following line:
         YACC_TABEXT = @YACC_TABEXT@
     The appropiate value for @YACC_TABEXT@ will be substituted
     by config.status.
  2: In the string containing the implicit rule for grammar files
     every occurence of ".tab" has been replaced by "$(YACC_TABEXT)".

In compile.am ".tab" has been replaced by "$(YACC_TABEXT)".
This are all modifications that are needed to get support for MSDOS ports
of BISON/BYACC.

From the written above it should be clear that neither the build-in support
for FLEX nor the new support for BISON can cope with explicit rules.
It is a feature of automake to copy explicit rules from makefile.am to makefile.in
without process them in any way. This is important for makefile.ins like the one
in gdb-4.18/gdb where a lot of explicit rules for grammar files exist.
All this rules must still be manually modified. Of course, every ".tab" string
can be replaced by "@YACC_TABEXT@" and  config.status will always recognize this
and replace "@YACC_TABEXT@" with the appropiate value but there is no real gain here.

IMPORTANT:
To avoid the posibility of overwritting existing y.tab.[ch] files
during the file name test, AC_PROG_YACC will invoke bison with
the -b option (file prefix). Unfortunatly the DJGPP port of bison
has a bug that will not allow to use this option. It is essential
to use a corrected bison version or the macro will not properly
work. If the bogus bison is used in a DOS box of WIN 3.XX it will
simply crash the box and on WIN9X the output file name will be:
actest.tab.c wich implies that YACC_TABEXT = .tab will be used
and an unix style makefile will be created.

The modified autoconf and automake have been tested on Linux and
MSDOS6.XX On both OS binutils 2.8/2.9.1, gdb-4.18, fileutils-3.16,
shellutils-1.16 and some other packages that use AUTOMAKE/AUTOCONF
have been succesfully configured and compiled.
No WIN9X testing at all.

The patches are based on AUTOCONF-2.13.TAR.GZ and AUTOMAKE-1.4.TAR.GZ
This means the GNU distributions and not the DJGPP ports. The last patch
is the small patch needed to correct the bison bug.

Although I have done this primarily for my own use
I hope it is of some use for someone else or at least
it serves as a starting point to implement the needed
support for bison's MSDOS port.

Suggestions, comments objections, etc are welcome.

A last suggestion:
In autoconf lines like the following one are used:
  if ! test -z "$COMSPEC$ComSpec"; then
I would suggest:
  if test "x$OSTYPE" = xMSDOS; then
OSTYPE is always set  to MSDOS, at least by bash 1.14.
and will clearly identify MSDOS code.

Regards,
Guerrero, Juan Manuel.

Patch for AUTOCONF.
diff -acrpNC3 aconf213.gnu/acspecif.m4 aconf213.djg/acspecif.m4
*** aconf213.gnu/acspecif.m4	Tue Jan  5 14:27:52 1999
--- aconf213.djg/acspecif.m4	Mon Dec  6 09:07:54 1999
*************** AC_DEFUN(AC_PROG_AWK,
*** 484,490 ****
  [AC_CHECK_PROGS(AWK, mawk gawk nawk awk, )])
  
  AC_DEFUN(AC_PROG_YACC,
! [AC_CHECK_PROGS(YACC, 'bison -y' byacc, yacc)])
  
  AC_DEFUN(AC_PROG_CPP,
  [AC_MSG_CHECKING(how to run the C preprocessor)
--- 484,509 ----
  [AC_CHECK_PROGS(AWK, mawk gawk nawk awk, )])
  
  AC_DEFUN(AC_PROG_YACC,
! [missing_dir=ifelse([$1],,`cd $ac_aux_dir && pwd`,$1)
! AC_CHECK_PROGS(YACC, 'bison -y' byacc yacc, "$missing_dir/missing bison")
! AC_CACHE_CHECK(yacc output file tab extension, ac_cv_prog_yacc_tab_extension,
! [# Minimal yacc program.
! cat > actest.y << EOF
! %%
! rule: /* empty */
!     ;
! EOF
! $YACC -b actest actest.y
! if test -f actest.tab.c; then
!   ac_cv_prog_yacc_tab_extension=.tab
! elif test -f actest_tab.c; then
!   ac_cv_prog_yacc_tab_extension=_tab
! else
!   AC_MSG_ERROR(cannot find output from $YACC; giving up)
! fi
! rm -f actest*])
! YACC_TABEXT=$ac_cv_prog_yacc_tab_extension
! AC_SUBST(YACC_TABEXT)])
  
  AC_DEFUN(AC_PROG_CPP,
  [AC_MSG_CHECKING(how to run the C preprocessor)
Patch for AUTOMAKE.
diff -acrpNC3 amake-14.gnu/automake.in amake-14.djg/automake.in
*** amake-14.gnu/automake.in	Fri Jan 15 07:42:36 1999
--- amake-14.djg/automake.in	Mon Dec  6 09:12:42 1999
*************** sub output_yacc_build_rule
*** 960,965 ****
--- 960,966 ----
      local ($suffix);
      ($suffix = $yacc_suffix) =~ tr/y/c/;
      push (@suffixes, $yacc_suffix, $suffix);
+     &define_configure_variable ('YACC_TABEXT');
  
      # Generate rule for c/c++.
      $output_rules .= "$yacc_suffix$suffix:\n\t";
*************** sub output_yacc_build_rule
*** 967,981 ****
      if ($use_ylwrap)
      {
  	$output_rules .= ('$(SHELL) $(YLWRAP)'
! 			  . ' "$(YACC)" $< y.tab.c $*' . $suffix
! 			  . ' y.tab.h $*.h -- $(AM_YFLAGS) $(YFLAGS)');
      }
      else
      {
  	$output_rules .= ('$(YACC) $(AM_YFLAGS) $(YFLAGS) $< && mv y.tab.c $*'
  			  . $suffix . "\n"
! 			  . "\tif test -f y.tab.h; then \\\n"
! 			  . "\tif cmp -s y.tab.h \$*.h; then rm -f y.tab.h; else mv y.tab.h \$*.h; fi; \\\n"
  			  . "\telse :; fi");
      }
      $output_rules .= "\n";
--- 968,982 ----
      if ($use_ylwrap)
      {
  	$output_rules .= ('$(SHELL) $(YLWRAP)'
! 			  . ' "$(YACC)" $< y$(YACC_TABEXT).c $*' . $suffix
! 			  . ' y$(YACC_TABEXT).h $*.h -- $(AM_YFLAGS) $(YFLAGS)');
      }
      else
      {
  	$output_rules .= ('$(YACC) $(AM_YFLAGS) $(YFLAGS) $< && mv y.tab.c $*'
  			  . $suffix . "\n"
! 			  . "\tif test -f y\$(YACC_TABEXT).h; then \\\n"
! 			  . "\tif cmp -s y\$(YACC_TABEXT).h \$*.h; then rm -f y\$(YACC_TABEXT).h; else mv y\$(YACC_TABEXT).h \$*.h; fi; \\\n"
  			  . "\telse :; fi");
      }
      $output_rules .= "\n";
diff -acrpNC3 amake-14.gnu/compile.am amake-14.djg/compile.am
*** amake-14.gnu/compile.am	Sun Sep 27 03:06:42 1998
--- amake-14.djg/compile.am	Mon Dec  6 09:13:16 1999
*************** OBJEXT	-rm -f *.$(OBJEXT)
*** 38,43 ****
  clean-compile:
  
  distclean-compile:
! 	-rm -f *.tab.c
  
  maintainer-clean-compile:
--- 38,43 ----
  clean-compile:
  
  distclean-compile:
! 	-rm -f *$(YACC_TABEXT).c
  
  maintainer-clean-compile:
Patch for BISON.
*** files.c~	Wed May 19 04:43:04 1999
--- files.c	Mon Nov 29 01:46:02 1999
*************** openfiles (void)
*** 195,205 ****
--- 195,209 ----
        /* Append `.tab'.  */
        strcpy (name_base, spec_file_prefix);
  #ifdef VMS
        strcat (name_base, "_tab");
  #else
+ #ifdef MSDOS
+       strcat (name_base, "_tab");
+ #else
        strcat (name_base, ".tab");
+ #endif
  #endif
  #ifdef MSDOS
        strlwr (name_base);
  #endif /* MSDOS */
      }