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    1 #!@PERL@
    2 # aclocal - create aclocal.m4 by scanning configure.ac      -*- perl -*-
    3 # @configure_input@
    4 # Copyright (C) 1996-2020 Free Software Foundation, Inc.
    5 
    6 # This program is free software; you can redistribute it and/or modify
    7 # it under the terms of the GNU General Public License as published by
    8 # the Free Software Foundation; either version 2, or (at your option)
    9 # any later version.
   10 
   11 # This program is distributed in the hope that it will be useful,
   12 # but WITHOUT ANY WARRANTY; without even the implied warranty of
   13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   14 # GNU General Public License for more details.
   15 
   16 # You should have received a copy of the GNU General Public License
   17 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
   18 
   19 # Written by Tom Tromey <tromey@redhat.com>, and
   20 # Alexandre Duret-Lutz <adl@gnu.org>.
   21 
   22 use 5.006;
   23 use strict;
   24 use warnings FATAL => 'all';
   25 
   26 BEGIN
   27 {
   28   unshift (@INC, '@datadir@/@PACKAGE@-@APIVERSION@')
   29     unless $ENV{AUTOMAKE_UNINSTALLED};
   30 }
   31 
   32 use File::Basename;
   33 use File::Path ();
   34 
   35 use Automake::Config;
   36 use Automake::General;
   37 use Automake::Configure_ac;
   38 use Automake::Channels;
   39 use Automake::ChannelDefs;
   40 use Automake::XFile;
   41 use Automake::FileUtils;
   42 
   43 # Some globals.
   44 
   45 # Support AC_CONFIG_MACRO_DIRS also with older autoconf.
   46 # FIXME: To be removed in Automake 2.0, once we can assume autoconf
   47 #        2.70 or later.
   48 # FIXME: keep in sync with 'internal/ac-config-macro-dirs.m4'.
   49 my $ac_config_macro_dirs_fallback =
   50   'm4_ifndef([AC_CONFIG_MACRO_DIRS], [' .
   51     'm4_defun([_AM_CONFIG_MACRO_DIRS], [])' .
   52     'm4_defun([AC_CONFIG_MACRO_DIRS], [_AM_CONFIG_MACRO_DIRS($@)])' .
   53   '])';
   54 
   55 # We do not operate in threaded mode.
   56 $perl_threads = 0;
   57 
   58 # Include paths for searching macros.  We search macros in this order:
   59 # user-supplied directories first, then the directory containing the
   60 # automake macros, and finally the system-wide directories for
   61 # third-party macros.
   62 # @user_includes can be augmented with -I or AC_CONFIG_MACRO_DIRS.
   63 # @automake_includes can be reset with the '--automake-acdir' option.
   64 # @system_includes can be augmented with the 'dirlist' file or the
   65 # ACLOCAL_PATH environment variable, and reset with the '--system-acdir'
   66 # option.
   67 my @user_includes = ();
   68 my @automake_includes = ('@datadir@/aclocal-' . $APIVERSION);
   69 my @system_includes = ('@datadir@/aclocal');
   70 
   71 # Whether we should copy M4 file in $user_includes[0].
   72 my $install = 0;
   73 
   74 # --diff
   75 my @diff_command;
   76 
   77 # --dry-run
   78 my $dry_run = 0;
   79 
   80 # configure.ac or configure.in.
   81 my $configure_ac;
   82 
   83 # Output file name.
   84 my $output_file = 'aclocal.m4';
   85 
   86 # Option --force.
   87 my $force_output = 0;
   88 
   89 # Modification time of the youngest dependency.
   90 my $greatest_mtime = 0;
   91 
   92 # Which macros have been seen.
   93 my %macro_seen = ();
   94 
   95 # Remember the order into which we scanned the files.
   96 # It's important to output the contents of aclocal.m4 in the opposite order.
   97 # (Definitions in first files we have scanned should override those from
   98 # later files.  So they must appear last in the output.)
   99 my @file_order = ();
  100 
  101 # Map macro names to file names.
  102 my %map = ();
  103 
  104 # Ditto, but records the last definition of each macro as returned by --trace.
  105 my %map_traced_defs = ();
  106 
  107 # Map basenames to macro names.
  108 my %invmap = ();
  109 
  110 # Map file names to file contents.
  111 my %file_contents = ();
  112 
  113 # Map file names to file types.
  114 my %file_type = ();
  115 use constant FT_USER => 1;
  116 use constant FT_AUTOMAKE => 2;
  117 use constant FT_SYSTEM => 3;
  118 
  119 # Map file names to included files (transitively closed).
  120 my %file_includes = ();
  121 
  122 # Files which have already been added.
  123 my %file_added = ();
  124 
  125 # Files that have already been scanned.
  126 my %scanned_configure_dep = ();
  127 
  128 # Serial numbers, for files that have one.
  129 # The key is the basename of the file,
  130 # the value is the serial number represented as a list.
  131 my %serial = ();
  132 
  133 # Matches a macro definition.
  134 #   AC_DEFUN([macroname], ...)
  135 # or
  136 #   AC_DEFUN(macroname, ...)
  137 # When macroname is '['-quoted , we accept any character in the name,
  138 # except ']'.  Otherwise macroname stops on the first ']', ',', ')',
  139 # or '\n' encountered.
  140 my $ac_defun_rx =
  141   "(?:AU_ALIAS|A[CU]_DEFUN|AC_DEFUN_ONCE)\\((?:\\[([^]]+)\\]|([^],)\n]+))";
  142 
  143 # Matches an AC_REQUIRE line.
  144 my $ac_require_rx = "AC_REQUIRE\\((?:\\[([^]]+)\\]|([^],)\n]+))\\)";
  145 
  146 # Matches an m4_include line.
  147 my $m4_include_rx = "(m4_|m4_s|s)include\\((?:\\[([^]]+)\\]|([^],)\n]+))\\)";
  148 
  149 # Match a serial number.
  150 my $serial_line_rx = '^#\s*serial\s+(\S*)';
  151 my $serial_number_rx = '^\d+(?:\.\d+)*$';
  152 
  153 # Autoconf version.  This variable is set by 'trace_used_macros'.
  154 my $ac_version;
  155 
  156 # User directory containing extra m4 files for macros definition,
  157 # as extracted from calls to the macro AC_CONFIG_MACRO_DIRS.
  158 # This variable is updated by 'trace_used_macros'.
  159 my @ac_config_macro_dirs;
  160 
  161 # If set, names a temporary file that must be erased on abnormal exit.
  162 my $erase_me;
  163 
  164 # Constants for the $ERR_LEVEL parameter of the 'scan_m4_dirs' function.
  165 use constant SCAN_M4_DIRS_SILENT => 0;
  166 use constant SCAN_M4_DIRS_WARN => 1;
  167 use constant SCAN_M4_DIRS_ERROR => 2;
  168 
  169 ################################################################
  170 
  171 # Prototypes for all subroutines.
  172 
  173 sub add_file ($);
  174 sub add_macro ($);
  175 sub check_acinclude ();
  176 sub install_file ($$);
  177 sub list_compare (\@\@);
  178 sub parse_ACLOCAL_PATH ();
  179 sub parse_arguments ();
  180 sub reset_maps ();
  181 sub scan_configure ();
  182 sub scan_configure_dep ($);
  183 sub scan_file ($$$);
  184 sub scan_m4_dirs ($$@);
  185 sub scan_m4_files ();
  186 sub strip_redundant_includes (%);
  187 sub trace_used_macros ();
  188 sub unlink_tmp (;$);
  189 sub usage ($);
  190 sub version ();
  191 sub write_aclocal ($@);
  192 sub xmkdir_p ($);
  193 
  194 ################################################################
  195 
  196 # Erase temporary file ERASE_ME.  Handle signals.
  197 sub unlink_tmp (;$)
  198 {
  199   my ($sig) = @_;
  200 
  201   if ($sig)
  202     {
  203       verb "caught SIG$sig, bailing out";
  204     }
  205   if (defined $erase_me && -e $erase_me && !unlink ($erase_me))
  206     {
  207       fatal "could not remove '$erase_me': $!";
  208     }
  209   undef $erase_me;
  210 
  211   # reraise default handler.
  212   if ($sig)
  213     {
  214       $SIG{$sig} = 'DEFAULT';
  215       kill $sig => $$;
  216     }
  217 }
  218 
  219 $SIG{'INT'} = $SIG{'TERM'} = $SIG{'QUIT'} = $SIG{'HUP'} = 'unlink_tmp';
  220 END { unlink_tmp }
  221 
  222 sub xmkdir_p ($)
  223 {
  224   my $dir = shift;
  225   local $@ = undef;
  226   return
  227     if -d $dir or eval { File::Path::mkpath $dir };
  228   chomp $@;
  229   $@ =~ s/\s+at\s.*\bline\s\d+.*$//;
  230   fatal "could not create directory '$dir': $@";
  231 }
  232 
  233 # Check macros in acinclude.m4.  If one is not used, warn.
  234 sub check_acinclude ()
  235 {
  236   foreach my $key (keys %map)
  237     {
  238       # FIXME: should print line number of acinclude.m4.
  239       msg ('syntax', "macro '$key' defined in acinclude.m4 but never used")
  240 	if $map{$key} eq 'acinclude.m4' && ! exists $macro_seen{$key};
  241     }
  242 }
  243 
  244 sub reset_maps ()
  245 {
  246   $greatest_mtime = 0;
  247   %macro_seen = ();
  248   @file_order = ();
  249   %map = ();
  250   %map_traced_defs = ();
  251   %file_contents = ();
  252   %file_type = ();
  253   %file_includes = ();
  254   %file_added = ();
  255   %scanned_configure_dep = ();
  256   %invmap = ();
  257   %serial = ();
  258   undef &search;
  259 }
  260 
  261 # install_file ($SRC, $DESTDIR)
  262 sub install_file ($$)
  263 {
  264   my ($src, $destdir) = @_;
  265   my $dest = $destdir . "/" . basename ($src);
  266   my $diff_dest;
  267 
  268   verb "installing $src to $dest";
  269 
  270   if ($force_output
  271       || !exists $file_contents{$dest}
  272       || $file_contents{$src} ne $file_contents{$dest})
  273     {
  274       if (-e $dest)
  275 	{
  276 	  msg 'note', "overwriting '$dest' with '$src'";
  277 	  $diff_dest = $dest;
  278 	}
  279       else
  280 	{
  281 	  msg 'note', "installing '$dest' from '$src'";
  282 	}
  283 
  284       if (@diff_command)
  285 	{
  286 	  if (! defined $diff_dest)
  287 	    {
  288 	      # $dest does not exist.  We create an empty one just to
  289 	      # run diff, and we erase it afterward.  Using the real
  290 	      # destination file (rather than a temporary file) is
  291 	      # good when diff is run with options that display the
  292 	      # file name.
  293 	      #
  294 	      # If creating $dest fails, fall back to /dev/null.  At
  295 	      # least one diff implementation (Tru64's) cannot deal
  296 	      # with /dev/null.  However working around this is not
  297 	      # worth the trouble since nobody run aclocal on a
  298 	      # read-only tree anyway.
  299 	      $erase_me = $dest;
  300 	      my $f = new IO::File "> $dest";
  301 	      if (! defined $f)
  302 		{
  303 		  undef $erase_me;
  304 		  $diff_dest = '/dev/null';
  305 		}
  306 	      else
  307 		{
  308 		  $diff_dest = $dest;
  309 		  $f->close;
  310 		}
  311 	    }
  312 	  my @cmd = (@diff_command, $diff_dest, $src);
  313 	  $! = 0;
  314 	  verb "running: @cmd";
  315 	  my $res = system (@cmd);
  316 	  Automake::FileUtils::handle_exec_errors "@cmd", 1
  317 	    if $res;
  318 	  unlink_tmp;
  319 	}
  320       elsif (!$dry_run)
  321 	{
  322           xmkdir_p ($destdir);
  323 	  xsystem ('cp', $src, $dest);
  324 	}
  325     }
  326 }
  327 
  328 # Compare two lists of numbers.
  329 sub list_compare (\@\@)
  330 {
  331   my @l = @{$_[0]};
  332   my @r = @{$_[1]};
  333   while (1)
  334     {
  335       if (0 == @l)
  336 	{
  337 	  return (0 == @r) ? 0 : -1;
  338 	}
  339       elsif (0 == @r)
  340 	{
  341 	  return 1;
  342 	}
  343       elsif ($l[0] < $r[0])
  344 	{
  345 	  return -1;
  346 	}
  347       elsif ($l[0] > $r[0])
  348 	{
  349 	  return 1;
  350 	}
  351       shift @l;
  352       shift @r;
  353     }
  354 }
  355 
  356 ################################################################
  357 
  358 # scan_m4_dirs($TYPE, $ERR_LEVEL, @DIRS)
  359 # -----------------------------------------------
  360 # Scan all M4 files installed in @DIRS for new macro definitions.
  361 # Register each file as of type $TYPE (one of the FT_* constants).
  362 # If a directory in @DIRS cannot be read:
  363 #  - fail hard                if $ERR_LEVEL == SCAN_M4_DIRS_ERROR
  364 #  - just print a warning     if $ERR_LEVEL == SCAN_M4_DIRS_WA
  365 #  - continue silently        if $ERR_LEVEL == SCAN_M4_DIRS_SILENT
  366 sub scan_m4_dirs ($$@)
  367 {
  368   my ($type, $err_level, @dirlist) = @_;
  369 
  370   foreach my $m4dir (@dirlist)
  371     {
  372       if (! opendir (DIR, $m4dir))
  373 	{
  374 	  # TODO: maybe avoid complaining only if errno == ENONENT?
  375           my $message = "couldn't open directory '$m4dir': $!";
  376 
  377           if ($err_level == SCAN_M4_DIRS_ERROR)
  378             {
  379               fatal $message;
  380             }
  381           elsif ($err_level == SCAN_M4_DIRS_WARN)
  382             {
  383               msg ('unsupported', $message);
  384               next;
  385             }
  386           elsif ($err_level == SCAN_M4_DIRS_SILENT)
  387             {
  388               next; # Silently ignore.
  389             }
  390           else
  391             {
  392                prog_error "invalid \$err_level value '$err_level'";
  393             }
  394 	}
  395 
  396       # We reverse the directory contents so that foo2.m4 gets
  397       # used in preference to foo1.m4.
  398       foreach my $file (reverse sort grep (! /^\./, readdir (DIR)))
  399 	{
  400 	  # Only examine .m4 files.
  401 	  next unless $file =~ /\.m4$/;
  402 
  403 	  # Skip some files when running out of srcdir.
  404 	  next if $file eq 'aclocal.m4';
  405 
  406 	  my $fullfile = File::Spec->canonpath ("$m4dir/$file");
  407 	  scan_file ($type, $fullfile, 'aclocal');
  408 	}
  409       closedir (DIR);
  410     }
  411 }
  412 
  413 # Scan all the installed m4 files and construct a map.
  414 sub scan_m4_files ()
  415 {
  416   # First, scan configure.ac.  It may contain macro definitions,
  417   # or may include other files that define macros.
  418   scan_file (FT_USER, $configure_ac, 'aclocal');
  419 
  420   # Then, scan acinclude.m4 if it exists.
  421   if (-f 'acinclude.m4')
  422     {
  423       scan_file (FT_USER, 'acinclude.m4', 'aclocal');
  424     }
  425 
  426   # Finally, scan all files in our search paths.
  427 
  428   if (@user_includes)
  429     {
  430       # Don't explore the same directory multiple times.  This is here not
  431       # only for speedup purposes.  We need this when the user has e.g.
  432       # specified 'ACLOCAL_AMFLAGS = -I m4' and has also set
  433       # AC_CONFIG_MACRO_DIR[S]([m4]) in configure.ac.  This makes the 'm4'
  434       # directory to occur twice here and fail on the second call to
  435       # scan_m4_dirs([m4]) when the 'm4' directory doesn't exist.
  436       # TODO: Shouldn't there be rather a check in scan_m4_dirs for
  437       #       @user_includes[0]?
  438       @user_includes = uniq @user_includes;
  439 
  440       # Don't complain if the first user directory doesn't exist, in case
  441       # we need to create it later (can happen if '--install' was given).
  442       scan_m4_dirs (FT_USER,
  443                     $install ? SCAN_M4_DIRS_SILENT : SCAN_M4_DIRS_WARN,
  444                     $user_includes[0]);
  445       scan_m4_dirs (FT_USER,
  446                     SCAN_M4_DIRS_ERROR,
  447 		    @user_includes[1..$#user_includes]);
  448     }
  449   scan_m4_dirs (FT_AUTOMAKE, SCAN_M4_DIRS_ERROR, @automake_includes);
  450   scan_m4_dirs (FT_SYSTEM, SCAN_M4_DIRS_ERROR, @system_includes);
  451 
  452   # Construct a new function that does the searching.  We use a
  453   # function (instead of just evaluating $search in the loop) so that
  454   # "die" is correctly and easily propagated if run.
  455   my $search = "sub search {\nmy \$found = 0;\n";
  456   foreach my $key (reverse sort keys %map)
  457     {
  458       $search .= ('if (/\b\Q' . $key . '\E(?!\w)/) { add_macro ("' . $key
  459 		  . '"); $found = 1; }' . "\n");
  460     }
  461   $search .= "return \$found;\n};\n";
  462   eval $search;
  463   prog_error "$@\n search is $search" if $@;
  464 }
  465 
  466 ################################################################
  467 
  468 # Add a macro to the output.
  469 sub add_macro ($)
  470 {
  471   my ($macro) = @_;
  472 
  473   # Ignore unknown required macros.  Either they are not really
  474   # needed (e.g., a conditional AC_REQUIRE), in which case aclocal
  475   # should be quiet, or they are needed and Autoconf itself will
  476   # complain when we trace for macro usage later.
  477   return unless defined $map{$macro};
  478 
  479   verb "saw macro $macro";
  480   $macro_seen{$macro} = 1;
  481   add_file ($map{$macro});
  482 }
  483 
  484 # scan_configure_dep ($file)
  485 # --------------------------
  486 # Scan a configure dependency (configure.ac, or separate m4 files)
  487 # for uses of known macros and AC_REQUIREs of possibly unknown macros.
  488 # Recursively scan m4_included files.
  489 sub scan_configure_dep ($)
  490 {
  491   my ($file) = @_;
  492   # Do not scan a file twice.
  493   return ()
  494     if exists $scanned_configure_dep{$file};
  495   $scanned_configure_dep{$file} = 1;
  496 
  497   my $mtime = mtime $file;
  498   $greatest_mtime = $mtime if $greatest_mtime < $mtime;
  499 
  500   my $contents = exists $file_contents{$file} ?
  501     $file_contents{$file} : contents $file;
  502 
  503   my $line = 0;
  504   my @rlist = ();
  505   my @ilist = ();
  506   foreach (split ("\n", $contents))
  507     {
  508       ++$line;
  509       # Remove comments from current line.
  510       s/\bdnl\b.*$//;
  511       s/\#.*$//;
  512       # Avoid running all the following regexes on white lines.
  513       next if /^\s*$/;
  514 
  515       while (/$m4_include_rx/go)
  516 	{
  517 	  my $ifile = $2 || $3;
  518 	  # Skip missing 'sinclude'd files.
  519 	  next if $1 ne 'm4_' && ! -f $ifile;
  520 	  push @ilist, $ifile;
  521 	}
  522 
  523       while (/$ac_require_rx/go)
  524 	{
  525 	  push (@rlist, $1 || $2);
  526 	}
  527 
  528       # The search function is constructed dynamically by
  529       # scan_m4_files.  The last parenthetical match makes sure we
  530       # don't match things that look like macro assignments or
  531       # AC_SUBSTs.
  532       if (! &search && /(^|\s+)(AM_[A-Z0-9_]+)($|[^\]\)=A-Z0-9_])/)
  533 	{
  534 	  # Macro not found, but AM_ prefix found.
  535 	  # Make this just a warning, because we do not know whether
  536 	  # the macro is actually used (it could be called conditionally).
  537 	  msg ('unsupported', "$file:$line",
  538 	       "macro '$2' not found in library");
  539 	}
  540     }
  541 
  542   add_macro ($_) foreach (@rlist);
  543   scan_configure_dep ($_) foreach @ilist;
  544 }
  545 
  546 # add_file ($FILE)
  547 # ----------------
  548 # Add $FILE to output.
  549 sub add_file ($)
  550 {
  551   my ($file) = @_;
  552 
  553   # Only add a file once.
  554   return if ($file_added{$file});
  555   $file_added{$file} = 1;
  556 
  557   scan_configure_dep $file;
  558 }
  559 
  560 # Point to the documentation for underquoted AC_DEFUN only once.
  561 my $underquoted_manual_once = 0;
  562 
  563 # scan_file ($TYPE, $FILE, $WHERE)
  564 # --------------------------------
  565 # Scan a single M4 file ($FILE), and all files it includes.
  566 # Return the list of included files.
  567 # $TYPE is one of FT_USER, FT_AUTOMAKE, or FT_SYSTEM, depending
  568 # on where the file comes from.
  569 # $WHERE is the location to use in the diagnostic if the file
  570 # does not exist.
  571 sub scan_file ($$$)
  572 {
  573   my ($type, $file, $where) = @_;
  574   my $basename = basename $file;
  575 
  576   # Do not scan the same file twice.
  577   return @{$file_includes{$file}} if exists $file_includes{$file};
  578   # Prevent potential infinite recursion (if two files include each other).
  579   return () if exists $file_contents{$file};
  580 
  581   unshift @file_order, $file;
  582 
  583   $file_type{$file} = $type;
  584 
  585   fatal "$where: file '$file' does not exist" if ! -e $file;
  586 
  587   my $fh = new Automake::XFile $file;
  588   my $contents = '';
  589   my @inc_files = ();
  590   my %inc_lines = ();
  591 
  592   my $defun_seen = 0;
  593   my $serial_seen = 0;
  594   my $serial_older = 0;
  595 
  596   while ($_ = $fh->getline)
  597     {
  598       # Ignore '##' lines.
  599       next if /^##/;
  600 
  601       $contents .= $_;
  602       my $line = $_;
  603 
  604       if ($line =~ /$serial_line_rx/go)
  605 	{
  606 	  my $number = $1;
  607 	  if ($number !~ /$serial_number_rx/go)
  608 	    {
  609 	      msg ('syntax', "$file:$.",
  610 		   "ill-formed serial number '$number', "
  611 		   . "expecting a version string with only digits and dots");
  612 	    }
  613 	  elsif ($defun_seen)
  614 	    {
  615 	      # aclocal removes all definitions from M4 file with the
  616 	      # same basename if a greater serial number is found.
  617 	      # Encountering a serial after some macros will undefine
  618 	      # these macros...
  619 	      msg ('syntax', "$file:$.",
  620 		   'the serial number must appear before any macro definition');
  621 	    }
  622 	  # We really care about serials only for non-automake macros
  623 	  # and when --install is used.  But the above diagnostics are
  624 	  # made regardless of this, because not using --install is
  625 	  # not a reason not the fix macro files.
  626 	  elsif ($install && $type != FT_AUTOMAKE)
  627 	    {
  628 	      $serial_seen = 1;
  629 	      my @new = split (/\./, $number);
  630 
  631 	      verb "$file:$.: serial $number";
  632 
  633 	      if (!exists $serial{$basename}
  634 		  || list_compare (@new, @{$serial{$basename}}) > 0)
  635 		{
  636 		  # Delete any definition we knew from the old macro.
  637 		  foreach my $def (@{$invmap{$basename}})
  638 		    {
  639 		      verb "$file:$.: ignoring previous definition of $def";
  640 		      delete $map{$def};
  641 		    }
  642 		  $invmap{$basename} = [];
  643 		  $serial{$basename} = \@new;
  644 		}
  645 	      else
  646 		{
  647 		  $serial_older = 1;
  648 		}
  649 	    }
  650 	}
  651 
  652       # Remove comments from current line.
  653       # Do not do it earlier, because the serial line is a comment.
  654       $line =~ s/\bdnl\b.*$//;
  655       $line =~ s/\#.*$//;
  656 
  657       while ($line =~ /$ac_defun_rx/go)
  658 	{
  659 	  $defun_seen = 1;
  660 	  if (! defined $1)
  661 	    {
  662 	      msg ('syntax', "$file:$.", "underquoted definition of $2"
  663 		   . "\n  run info Automake 'Extending aclocal'\n"
  664 		   . "  or see https://www.gnu.org/software/automake/manual/"
  665 		   . "automake.html#Extending-aclocal")
  666 		unless $underquoted_manual_once;
  667 	      $underquoted_manual_once = 1;
  668 	    }
  669 
  670 	  # If this macro does not have a serial and we have already
  671 	  # seen a macro with the same basename earlier, we should
  672 	  # ignore the macro (don't exit immediately so we can still
  673 	  # diagnose later #serial numbers and underquoted macros).
  674 	  $serial_older ||= ($type != FT_AUTOMAKE
  675 			     && !$serial_seen && exists $serial{$basename});
  676 
  677 	  my $macro = $1 || $2;
  678 	  if (!$serial_older && !defined $map{$macro})
  679 	    {
  680 	      verb "found macro $macro in $file: $.";
  681 	      $map{$macro} = $file;
  682 	      push @{$invmap{$basename}}, $macro;
  683 	    }
  684 	  else
  685 	    {
  686 	      # Note: we used to give an error here if we saw a
  687 	      # duplicated macro.  However, this turns out to be
  688 	      # extremely unpopular.  It causes actual problems which
  689 	      # are hard to work around, especially when you must
  690 	      # mix-and-match tool versions.
  691 	      verb "ignoring macro $macro in $file: $.";
  692 	    }
  693 	}
  694 
  695       while ($line =~ /$m4_include_rx/go)
  696 	{
  697 	  my $ifile = $2 || $3;
  698 	  # Skip missing 'sinclude'd files.
  699 	  next if $1 ne 'm4_' && ! -f $ifile;
  700 	  push (@inc_files, $ifile);
  701 	  $inc_lines{$ifile} = $.;
  702 	}
  703     }
  704 
  705   # Ignore any file that has an old serial (or no serial if we know
  706   # another one with a serial).
  707   return ()
  708     if ($serial_older ||
  709 	($type != FT_AUTOMAKE && !$serial_seen && exists $serial{$basename}));
  710 
  711   $file_contents{$file} = $contents;
  712 
  713   # For some reason I don't understand, it does not work
  714   # to do "map { scan_file ($_, ...) } @inc_files" below.
  715   # With Perl 5.8.2 it undefines @inc_files.
  716   my @copy = @inc_files;
  717   my @all_inc_files = (@inc_files,
  718 		       map { scan_file ($type, $_,
  719 					"$file:$inc_lines{$_}") } @copy);
  720   $file_includes{$file} = \@all_inc_files;
  721   return @all_inc_files;
  722 }
  723 
  724 # strip_redundant_includes (%FILES)
  725 # ---------------------------------
  726 # Each key in %FILES is a file that must be present in the output.
  727 # However some of these files might already include other files in %FILES,
  728 # so there is no point in including them another time.
  729 # This removes items of %FILES which are already included by another file.
  730 sub strip_redundant_includes (%)
  731 {
  732   my %files = @_;
  733 
  734   # Always include acinclude.m4, even if it does not appear to be used.
  735   $files{'acinclude.m4'} = 1 if -f 'acinclude.m4';
  736   # File included by $configure_ac are redundant.
  737   $files{$configure_ac} = 1;
  738 
  739   # Files at the end of @file_order should override those at the beginning,
  740   # so it is important to preserve these trailing files.  We can remove
  741   # a file A if it is going to be output before a file B that includes
  742   # file A, not the converse.
  743   foreach my $file (reverse @file_order)
  744     {
  745       next unless exists $files{$file};
  746       foreach my $ifile (@{$file_includes{$file}})
  747 	{
  748 	  next unless exists $files{$ifile};
  749 	  delete $files{$ifile};
  750 	  verb "$ifile is already included by $file";
  751 	}
  752     }
  753 
  754   # configure.ac is implicitly included.
  755   delete $files{$configure_ac};
  756 
  757   return %files;
  758 }
  759 
  760 sub trace_used_macros ()
  761 {
  762   my %files = map { $map{$_} => 1 } keys %macro_seen;
  763   %files = strip_redundant_includes %files;
  764 
  765   # Suppress all warnings from this invocation of autom4te.
  766   # In particular we want to avoid spurious warnings about
  767   # macros being "m4_require'd but not m4_defun'd" because
  768   # aclocal.m4 is not yet available.
  769   local $ENV{WARNINGS} = 'none';
  770 
  771   my $traces = ($ENV{AUTOM4TE} || '@am_AUTOM4TE@');
  772   $traces .= " --language Autoconf-without-aclocal-m4 ";
  773 
  774   # Support AC_CONFIG_MACRO_DIRS also with older autoconf.
  775   # Note that we can't use '$ac_config_macro_dirs_fallback' here, because
  776   # a bug in option parsing code of autom4te 2.68 and earlier would cause
  777   # it to read standard input last, even if the "-" argument was specified
  778   # early.
  779   # FIXME: To be removed in Automake 2.0, once we can assume autoconf
  780   #        2.70 or later.
  781   $traces .= "$automake_includes[0]/internal/ac-config-macro-dirs.m4 ";
  782 
  783   # All candidate files.
  784   $traces .= join (' ',
  785 		   (map { "'$_'" }
  786 		    (grep { exists $files{$_} } @file_order))) . " ";
  787 
  788   # All candidate macros.
  789   $traces .= join (' ',
  790 		   (map { "--trace='$_:\$f::\$n::\${::}%'" }
  791 		    ('AC_DEFUN',
  792 		     'AC_DEFUN_ONCE',
  793 		     'AU_DEFUN',
  794 		     '_AM_AUTOCONF_VERSION',
  795 		     'AC_CONFIG_MACRO_DIR_TRACE',
  796                      # FIXME: Tracing the next two macros is a hack for
  797                      # compatibility with older autoconf.  Remove this in
  798                      # Automake 2.0, when we can assume Autoconf 2.70 or
  799                      # later.
  800 		     'AC_CONFIG_MACRO_DIR',
  801 		     '_AM_CONFIG_MACRO_DIRS')),
  802 		   # Do not trace $1 for all other macros as we do
  803 		   # not need it and it might contains harmful
  804 		   # characters (like newlines).
  805 		   (map { "--trace='$_:\$f::\$n'" } (keys %macro_seen)));
  806 
  807   verb "running WARNINGS=$ENV{WARNINGS} $traces $configure_ac";
  808 
  809   my $tracefh = new Automake::XFile ("$traces $configure_ac |");
  810 
  811   @ac_config_macro_dirs = ();
  812 
  813   my %traced = ();
  814 
  815   while ($_ = $tracefh->getline)
  816     {
  817       chomp;
  818       my ($file, $macro, $arg1) = split (/::/);
  819 
  820       $traced{$macro} = 1 if exists $macro_seen{$macro};
  821 
  822       if ($macro eq 'AC_DEFUN' || $macro eq 'AC_DEFUN_ONCE'
  823             || $macro eq 'AU_DEFUN')
  824         {
  825           $map_traced_defs{$arg1} = $file;
  826         }
  827       elsif ($macro eq '_AM_AUTOCONF_VERSION')
  828         {
  829           $ac_version = $arg1;
  830         }
  831       elsif ($macro eq 'AC_CONFIG_MACRO_DIR_TRACE')
  832         {
  833           push @ac_config_macro_dirs, $arg1;
  834         }
  835       # FIXME: We still need to trace AC_CONFIG_MACRO_DIR
  836       # for compatibility with older autoconf.  Remove this
  837       # once we can assume Autoconf 2.70 or later.
  838       elsif ($macro eq 'AC_CONFIG_MACRO_DIR')
  839         {
  840           @ac_config_macro_dirs = ($arg1);
  841         }
  842       # FIXME:This is an hack for compatibility with older autoconf.
  843       # Remove this once we can assume Autoconf 2.70 or later.
  844       elsif ($macro eq '_AM_CONFIG_MACRO_DIRS')
  845         {
  846            # Empty leading/trailing fields might be produced by split,
  847            # hence the grep is really needed.
  848            push @ac_config_macro_dirs, grep (/./, (split /\s+/, $arg1));
  849         }
  850     }
  851 
  852   # FIXME: in Autoconf >= 2.70, AC_CONFIG_MACRO_DIR calls
  853   # AC_CONFIG_MACRO_DIR_TRACE behind the scenes, which could
  854   # leave unwanted duplicates in @ac_config_macro_dirs.
  855   # Remove this in Automake 2.0, when we'll stop tracing
  856   # AC_CONFIG_MACRO_DIR explicitly.
  857   @ac_config_macro_dirs = uniq @ac_config_macro_dirs;
  858 
  859   $tracefh->close;
  860 
  861   return %traced;
  862 }
  863 
  864 sub scan_configure ()
  865 {
  866   # Make sure we include acinclude.m4 if it exists.
  867   if (-f 'acinclude.m4')
  868     {
  869       add_file ('acinclude.m4');
  870     }
  871   scan_configure_dep ($configure_ac);
  872 }
  873 
  874 ################################################################
  875 
  876 # Write output.
  877 # Return 0 iff some files were installed locally.
  878 sub write_aclocal ($@)
  879 {
  880   my ($output_file, @macros) = @_;
  881   my $output = '';
  882 
  883   my %files = ();
  884   # Get the list of files containing definitions for the macros used.
  885   # (Filter out unused macro definitions with $map_traced_defs.  This
  886   # can happen when an Autoconf macro is conditionally defined:
  887   # aclocal sees the potential definition, but this definition is
  888   # actually never processed and the Autoconf implementation is used
  889   # instead.)
  890   for my $m (@macros)
  891     {
  892       $files{$map{$m}} = 1
  893 	if (exists $map_traced_defs{$m}
  894 	    && $map{$m} eq $map_traced_defs{$m});
  895     }
  896   # Do not explicitly include a file that is already indirectly included.
  897   %files = strip_redundant_includes %files;
  898 
  899   my $installed = 0;
  900 
  901   for my $file (grep { exists $files{$_} } @file_order)
  902     {
  903       # Check the time stamp of this file, and of all files it includes.
  904       for my $ifile ($file, @{$file_includes{$file}})
  905 	{
  906 	  my $mtime = mtime $ifile;
  907 	  $greatest_mtime = $mtime if $greatest_mtime < $mtime;
  908 	}
  909 
  910       # If the file to add looks like outside the project, copy it
  911       # to the output.  The regex catches filenames starting with
  912       # things like '/', '\', or 'c:\'.
  913       if ($file_type{$file} != FT_USER
  914 	  || $file =~ m,^(?:\w:)?[\\/],)
  915 	{
  916 	  if (!$install || $file_type{$file} != FT_SYSTEM)
  917 	    {
  918 	      # Copy the file into aclocal.m4.
  919 	      $output .= $file_contents{$file} . "\n";
  920 	    }
  921 	  else
  922 	    {
  923 	      # Install the file (and any file it includes).
  924 	      my $dest;
  925 	      for my $ifile (@{$file_includes{$file}}, $file)
  926 		{
  927 		  install_file ($ifile, $user_includes[0]);
  928 		}
  929 	      $installed = 1;
  930 	    }
  931 	}
  932       else
  933 	{
  934 	  # Otherwise, simply include the file.
  935 	  $output .= "m4_include([$file])\n";
  936 	}
  937     }
  938 
  939   if ($installed)
  940     {
  941       verb "running aclocal anew, because some files were installed locally";
  942       return 0;
  943     }
  944 
  945   # Nothing to output?!
  946   # FIXME: Shouldn't we diagnose this?
  947   return 1 if ! length ($output);
  948 
  949   if ($ac_version)
  950     {
  951       # Do not use "$output_file" here for the same reason we do not
  952       # use it in the header below.  autom4te will output the name of
  953       # the file in the diagnostic anyway.
  954       $output = "m4_ifndef([AC_AUTOCONF_VERSION],
  955   [m4_copy([m4_PACKAGE_VERSION], [AC_AUTOCONF_VERSION])])dnl
  956 m4_if(m4_defn([AC_AUTOCONF_VERSION]), [$ac_version],,
  957 [m4_warning([this file was generated for autoconf $ac_version.
  958 You have another version of autoconf.  It may work, but is not guaranteed to.
  959 If you have problems, you may need to regenerate the build system entirely.
  960 To do so, use the procedure documented by the package, typically 'autoreconf'.])])
  961 
  962 $output";
  963     }
  964 
  965   # We used to print "# $output_file generated automatically etc."  But
  966   # this creates spurious differences when using autoreconf.  Autoreconf
  967   # creates aclocal.m4t and then rename it to aclocal.m4, but the
  968   # rebuild rules generated by Automake create aclocal.m4 directly --
  969   # this would gives two ways to get the same file, with a different
  970   # name in the header.
  971   $output = "# generated automatically by aclocal $VERSION -*- Autoconf -*-
  972 
  973 # Copyright (C) 1996-$RELEASE_YEAR Free Software Foundation, Inc.
  974 
  975 # This file is free software; the Free Software Foundation
  976 # gives unlimited permission to copy and/or distribute it,
  977 # with or without modifications, as long as this notice is preserved.
  978 
  979 # This program is distributed in the hope that it will be useful,
  980 # but WITHOUT ANY WARRANTY, to the extent permitted by law; without
  981 # even the implied warranty of MERCHANTABILITY or FITNESS FOR A
  982 # PARTICULAR PURPOSE.
  983 
  984 $ac_config_macro_dirs_fallback
  985 $output";
  986 
  987   # We try not to update $output_file unless necessary, because
  988   # doing so invalidate Autom4te's cache and therefore slows down
  989   # tools called after aclocal.
  990   #
  991   # We need to overwrite $output_file in the following situations.
  992   #   * The --force option is in use.
  993   #   * One of the dependencies is younger.
  994   #     (Not updating $output_file in this situation would cause
  995   #     make to call aclocal in loop.)
  996   #   * The contents of the current file are different from what
  997   #     we have computed.
  998   if (!$force_output
  999       && $greatest_mtime < mtime ($output_file)
 1000       && $output eq contents ($output_file))
 1001     {
 1002       verb "$output_file unchanged";
 1003       return 1;
 1004     }
 1005 
 1006   verb "writing $output_file";
 1007 
 1008   if (!$dry_run)
 1009     {
 1010       if (-e $output_file && !unlink $output_file)
 1011         {
 1012 	  fatal "could not remove '$output_file': $!";
 1013 	}
 1014       my $out = new Automake::XFile "> $output_file";
 1015       print $out $output;
 1016     }
 1017   return 1;
 1018 }
 1019 
 1020 ################################################################
 1021 
 1022 # Print usage and exit.
 1023 sub usage ($)
 1024 {
 1025   my ($status) = @_;
 1026 
 1027   print <<'EOF';
 1028 Usage: aclocal [OPTION]...
 1029 
 1030 Generate 'aclocal.m4' by scanning 'configure.ac' or 'configure.in'
 1031 
 1032 Options:
 1033       --automake-acdir=DIR  directory holding automake-provided m4 files
 1034       --system-acdir=DIR    directory holding third-party system-wide files
 1035       --diff[=COMMAND]      run COMMAND [diff -u] on M4 files that would be
 1036                             changed (implies --install and --dry-run)
 1037       --dry-run             pretend to, but do not actually update any file
 1038       --force               always update output file
 1039       --help                print this help, then exit
 1040   -I DIR                    add directory to search list for .m4 files
 1041       --install             copy third-party files to the first -I directory
 1042       --output=FILE         put output in FILE (default aclocal.m4)
 1043       --print-ac-dir        print name of directory holding system-wide
 1044                               third-party m4 files, then exit
 1045       --verbose             don't be silent
 1046       --version             print version number, then exit
 1047   -W, --warnings=CATEGORY   report the warnings falling in CATEGORY
 1048 EOF
 1049 
 1050   print Automake::ChannelDefs::usage (), "\n";
 1051 
 1052   print <<'EOF';
 1053 Report bugs to <@PACKAGE_BUGREPORT@>.
 1054 GNU Automake home page: <@PACKAGE_URL@>.
 1055 General help using GNU software: <https://www.gnu.org/gethelp/>.
 1056 EOF
 1057   exit $status;
 1058 }
 1059 
 1060 # Print version and exit.
 1061 sub version ()
 1062 {
 1063   print <<EOF;
 1064 aclocal (GNU $PACKAGE) $VERSION
 1065 Copyright (C) $RELEASE_YEAR Free Software Foundation, Inc.
 1066 License GPLv2+: GNU GPL version 2 or later <https://gnu.org/licenses/gpl-2.0.html>
 1067 This is free software: you are free to change and redistribute it.
 1068 There is NO WARRANTY, to the extent permitted by law.
 1069 
 1070 Written by Tom Tromey <tromey\@redhat.com>
 1071        and Alexandre Duret-Lutz <adl\@gnu.org>.
 1072 EOF
 1073   exit 0;
 1074 }
 1075 
 1076 # Parse command line.
 1077 sub parse_arguments ()
 1078 {
 1079   my $print_and_exit = 0;
 1080   my $diff_command;
 1081   my @warnings = ();
 1082 
 1083   my %cli_options =
 1084     (
 1085      'help'		=> sub { usage(0); },
 1086      'version'		=> \&version,
 1087      'system-acdir=s'	=> sub { shift; @system_includes = @_; },
 1088      'automake-acdir=s'	=> sub { shift; @automake_includes = @_; },
 1089      'diff:s'		=> \$diff_command,
 1090      'dry-run'		=> \$dry_run,
 1091      'force'		=> \$force_output,
 1092      'I=s'		=> \@user_includes,
 1093      'install'          => \$install,
 1094      'output=s'		=> \$output_file,
 1095      'print-ac-dir'     => \$print_and_exit,
 1096      'verbose'		=> sub { setup_channel 'verb', silent => 0; },
 1097      'W|warnings=s'     => \@warnings,
 1098      );
 1099 
 1100   use Automake::Getopt ();
 1101   Automake::Getopt::parse_options %cli_options;
 1102   parse_warnings @warnings;
 1103 
 1104   if (@ARGV > 0)
 1105     {
 1106       fatal ("non-option arguments are not accepted: '$ARGV[0]'.\n"
 1107              . "Try '$0 --help' for more information.");
 1108     }
 1109 
 1110   if ($print_and_exit)
 1111     {
 1112       print "@system_includes\n";
 1113       exit 0;
 1114     }
 1115 
 1116   if (defined $diff_command)
 1117     {
 1118       $diff_command = 'diff -u' if $diff_command eq '';
 1119       @diff_command = split (' ', $diff_command);
 1120       $install = 1;
 1121       $dry_run = 1;
 1122     }
 1123 
 1124   # Finally, adds any directory listed in the 'dirlist' file.
 1125   if (@system_includes && open (DIRLIST, "$system_includes[0]/dirlist"))
 1126     {
 1127       while (<DIRLIST>)
 1128         {
 1129           # Ignore '#' lines.
 1130           next if /^#/;
 1131           # strip off newlines and end-of-line comments
 1132           s/\s*\#.*$//;
 1133           chomp;
 1134           foreach my $dir (glob)
 1135             {
 1136               push (@system_includes, $dir) if -d $dir;
 1137             }
 1138         }
 1139       close (DIRLIST);
 1140     }
 1141 }
 1142 
 1143 # Add any directory listed in the 'ACLOCAL_PATH' environment variable
 1144 # to the list of system include directories.
 1145 sub parse_ACLOCAL_PATH ()
 1146 {
 1147   return if not defined $ENV{"ACLOCAL_PATH"};
 1148   # Directories in ACLOCAL_PATH should take precedence over system
 1149   # directories, so we use unshift.  However, directories that
 1150   # come first in ACLOCAL_PATH take precedence over directories
 1151   # coming later, which is why the result of split is reversed.
 1152   foreach my $dir (reverse split /:/, $ENV{"ACLOCAL_PATH"})
 1153     {
 1154       unshift (@system_includes, $dir) if $dir ne '' && -d $dir;
 1155     }
 1156 }
 1157 
 1158 ################################################################
 1159 
 1160 # Don't refer to installation directories from the build environment
 1161 if (exists $ENV{"AUTOMAKE_UNINSTALLED"})
 1162   {
 1163     @automake_includes = ();
 1164     @system_includes = ();
 1165   }
 1166 
 1167 @automake_includes = ($ENV{"ACLOCAL_AUTOMAKE_DIR"})
 1168   if (exists $ENV{"ACLOCAL_AUTOMAKE_DIR"});
 1169 
 1170 parse_WARNINGS;		    # Parse the WARNINGS environment variable.
 1171 parse_arguments;
 1172 parse_ACLOCAL_PATH;
 1173 $configure_ac = require_configure_ac;
 1174 
 1175 # We may have to rerun aclocal if some file have been installed, but
 1176 # it should not happen more than once.  The reason we must run again
 1177 # is that once the file has been moved from /usr/share/aclocal/ to the
 1178 # local m4/ directory it appears at a new place in the search path,
 1179 # hence it should be output at a different position in aclocal.m4.  If
 1180 # we did not rerun aclocal, the next run of aclocal would produce a
 1181 # different aclocal.m4.
 1182 my $loop = 0;
 1183 my $rerun_due_to_macrodir = 0;
 1184 while (1)
 1185   {
 1186     ++$loop;
 1187     prog_error "too many loops" if $loop > 2 + $rerun_due_to_macrodir;
 1188 
 1189     reset_maps;
 1190     scan_m4_files;
 1191     scan_configure;
 1192     last if $exit_code;
 1193     my %macro_traced = trace_used_macros;
 1194 
 1195     if (!$rerun_due_to_macrodir && @ac_config_macro_dirs)
 1196       {
 1197         # The directory specified in calls to the AC_CONFIG_MACRO_DIRS
 1198         # m4 macro (if any) must go after the user includes specified
 1199         # explicitly with the '-I' option.
 1200         push @user_includes, @ac_config_macro_dirs;
 1201         # We might have to scan some new directory of .m4 files.
 1202         $rerun_due_to_macrodir++;
 1203         next;
 1204       }
 1205 
 1206     if ($install && !@user_includes)
 1207       {
 1208         fatal "installation of third-party macros impossible without " .
 1209               "-I options nor AC_CONFIG_MACRO_DIR{,S} m4 macro(s)";
 1210       }
 1211 
 1212     last if write_aclocal ($output_file, keys %macro_traced);
 1213     last if $dry_run;
 1214   }
 1215 check_acinclude;
 1216 
 1217 exit $exit_code;