1 package ExtUtils::Liblist;
3 @ISA = qw(ExtUtils::Liblist::Kid File::Spec);
8 opendir my $dir, $_[0];
9 grep /$rex/, readdir $dir;
12 sub file_name_is_absolute {
15 'File::Spec'->file_name_is_absolute(@_);
19 package ExtUtils::Liblist::Kid;
21 # This kid package is to be used by MakeMaker. It will not work if
22 # $self is not a Makemaker.
25 # Broken out of MakeMaker from version 4.11
27 our $VERSION = substr q$Revision: 1.27 $, 10;
34 if ($^O eq 'VMS') { return &_vms_ext; }
35 elsif($^O eq 'MSWin32') { return &_win32_ext; }
36 else { return &_unix_os2_ext; }
40 my($self,$potential_libs, $verbose, $give_libs) = @_;
41 if ($^O =~ 'os2' and $Config{perllibs}) {
42 # Dynamic libraries are not transitive, so we may need including
43 # the libraries linked against perl.dll again.
45 $potential_libs .= " " if $potential_libs;
46 $potential_libs .= $Config{perllibs};
48 return ("", "", "", "", ($give_libs ? [] : ())) unless $potential_libs;
49 warn "Potential libraries are '$potential_libs':\n" if $verbose;
51 my($so) = $Config{'so'};
52 my($libs) = $Config{'perllibs'};
53 my $Config_libext = $Config{lib_ext} || ".a";
56 # compute $extralibs, $bsloadlibs and $ldloadlibs from
58 # this is a rewrite of Andy Dougherty's extliblist in perl
60 my(@searchpath); # from "-L/path" entries in $potential_libs
61 my(@libpath) = split " ", $Config{'libpth'};
62 my(@ldloadlibs, @bsloadlibs, @extralibs, @ld_run_path, %ld_run_path_seen);
63 my(@libs, %libs_seen);
64 my($fullname, $thislib, $thispth, @fullname);
65 my($pwd) = cwd(); # from Cwd.pm
68 foreach $thislib (split ' ', $potential_libs){
70 # Handle possible linker path arguments.
71 if ($thislib =~ s/^(-[LR]|-Wl,-R)//){ # save path flag type
74 warn "$ptype$thislib ignored, directory does not exist\n"
79 if (($ptype eq '-R') or ($ptype eq '-Wl,-R')) {
80 if ($Config{'lddlflags'} =~ /-Wl,-R/) {
82 } elsif ($Config{'lddlflags'} =~ /-R/) {
86 unless ($self->file_name_is_absolute($thislib)) {
87 warn "Warning: $ptype$thislib changed to $ptype$pwd/$thislib\n";
88 $thislib = $self->catdir($pwd,$thislib);
90 push(@searchpath, $thislib);
91 push(@extralibs, "$ptype$thislib");
92 push(@ldloadlibs, "$rtype$thislib");
96 # Handle possible library arguments.
97 unless ($thislib =~ s/^-l//){
98 warn "Unrecognized argument in LIBS ignored: '$thislib'\n";
103 foreach $thispth (@searchpath, @libpath){
105 # Try to find the full name of the library. We need this to
106 # determine whether it's a dynamically-loadable library or not.
107 # This tends to be subject to various os-specific quirks.
108 # For gcc-2.6.2 on linux (March 1995), DLD can not load
109 # .sa libraries, with the exception of libm.sa, so we
110 # deliberately skip them.
112 $self->lsdir($thispth,"^\Qlib$thislib.$so.\E[0-9]+")){
113 # Take care that libfoo.so.10 wins against libfoo.so.9.
114 # Compare two libraries to find the most recent version
115 # number. E.g. if you have libfoo.so.9.0.7 and
116 # libfoo.so.10.1, first convert all digits into two
117 # decimal places. Then we'll add ".00" to the shorter
118 # strings so that we're comparing strings of equal length
119 # Thus we'll compare libfoo.so.09.07.00 with
120 # libfoo.so.10.01.00. Some libraries might have letters
121 # in the version. We don't know what they mean, but will
122 # try to skip them gracefully -- we'll set any letter to
123 # '0'. Finally, sort in reverse so we can take the
126 #TODO: iterate through the directory instead of sorting
128 $fullname = "$thispth/" .
129 (sort { my($ma) = $a;
131 $ma =~ tr/A-Za-z/0/s;
132 $ma =~ s/\b(\d)\b/0$1/g;
133 $mb =~ tr/A-Za-z/0/s;
134 $mb =~ s/\b(\d)\b/0$1/g;
135 while (length($ma) < length($mb)) { $ma .= ".00"; }
136 while (length($mb) < length($ma)) { $mb .= ".00"; }
137 # Comparison deliberately backwards
138 $mb cmp $ma;} @fullname)[0];
139 } elsif (-f ($fullname="$thispth/lib$thislib.$so")
140 && (($Config{'dlsrc'} ne "dl_dld.xs") || ($thislib eq "m"))){
141 } elsif (-f ($fullname="$thispth/lib${thislib}_s$Config_libext")
142 && (! $Config{'archname'} =~ /RM\d\d\d-svr4/)
143 && ($thislib .= "_s") ){ # we must explicitly use _s version
144 } elsif (-f ($fullname="$thispth/lib$thislib$Config_libext")){
145 } elsif (-f ($fullname="$thispth/$thislib$Config_libext")){
146 } elsif (-f ($fullname="$thispth/Slib$thislib$Config_libext")){
147 } elsif ($^O eq 'dgux'
148 && -l ($fullname="$thispth/lib$thislib$Config_libext")
149 && readlink($fullname) =~ /^elink:/s) {
150 # Some of DG's libraries look like misconnected symbolic
151 # links, but development tools can follow them. (They
154 # libm.a -> elink:${SDE_PATH:-/usr}/sde/\
155 # ${TARGET_BINARY_INTERFACE:-m88kdgux}/usr/lib/libm.a
157 # , the compilation tools expand the environment variables.)
159 warn "$thislib not found in $thispth\n" if $verbose;
162 warn "'-l$thislib' found at $fullname\n" if $verbose;
163 my($fullnamedir) = dirname($fullname);
164 push @ld_run_path, $fullnamedir unless $ld_run_path_seen{$fullnamedir}++;
165 push @libs, $fullname unless $libs_seen{$fullname}++;
169 # Now update library lists
171 # what do we know about this library...
172 my $is_dyna = ($fullname !~ /\Q$Config_libext\E\z/);
173 my $in_perl = ($libs =~ /\B-l\Q$ {thislib}\E\b/s);
175 # Do not add it into the list if it is already linked in
176 # with the main perl executable.
177 # We have to special-case the NeXT, because math and ndbm
178 # are both in libsys_s
180 ($Config{'osname'} eq 'next' &&
181 ($thislib eq 'm' || $thislib eq 'ndbm')) ){
182 push(@extralibs, "-l$thislib");
185 # We might be able to load this archive file dynamically
186 if ( ($Config{'dlsrc'} =~ /dl_next/ && $Config{'osvers'} lt '4_0')
187 || ($Config{'dlsrc'} =~ /dl_dld/) )
189 # We push -l$thislib instead of $fullname because
190 # it avoids hardwiring a fixed path into the .bs file.
191 # Mkbootstrap will automatically add dl_findfile() to
192 # the .bs file if it sees a name in the -l format.
193 # USE THIS, when dl_findfile() is fixed:
194 # push(@bsloadlibs, "-l$thislib");
195 # OLD USE WAS while checking results against old_extliblist
196 push(@bsloadlibs, "$fullname");
199 # For SunOS4, do not add in this shared library if
200 # it is already linked in the main perl executable
201 push(@ldloadlibs, "-l$thislib")
202 unless ($in_perl and $^O eq 'sunos');
204 push(@ldloadlibs, "-l$thislib");
207 last; # found one here so don't bother looking further
209 warn "Note (probably harmless): "
210 ."No library found for -l$thislib\n"
213 return ('','','','', ($give_libs ? \@libs : ())) unless $found;
214 ("@extralibs", "@bsloadlibs", "@ldloadlibs",join(":",@ld_run_path), ($give_libs ? \@libs : ()));
219 require Text::ParseWords;
221 my($self, $potential_libs, $verbose, $give_libs) = @_;
223 # If user did not supply a list, we punt.
224 # (caller should probably use the list in $Config{libs})
225 return ("", "", "", "", ($give_libs ? [] : ())) unless $potential_libs;
227 my $cc = $Config{cc};
228 my $VC = 1 if $cc =~ /^cl/i;
229 my $BC = 1 if $cc =~ /^bcc/i;
230 my $GC = 1 if $cc =~ /^gcc/i;
231 my $so = $Config{'so'};
232 my $libs = $Config{'perllibs'};
233 my $libpth = $Config{'libpth'};
234 my $libext = $Config{'lib_ext'} || ".lib";
235 my(@libs, %libs_seen);
237 if ($libs and $potential_libs !~ /:nodefault/i) {
238 # If Config.pm defines a set of default libs, we always
239 # tack them on to the user-supplied list, unless the user
240 # specified :nodefault
242 $potential_libs .= " " if $potential_libs;
243 $potential_libs .= $libs;
245 warn "Potential libraries are '$potential_libs':\n" if $verbose;
247 # normalize to forward slashes
249 $potential_libs =~ s,\\,/,g;
251 # compute $extralibs from $potential_libs
253 my @searchpath; # from "-L/path" in $potential_libs
254 my @libpath = Text::ParseWords::quotewords('\s+', 0, $libpth);
256 my $pwd = cwd(); # from Cwd.pm
260 my($fullname, $thislib, $thispth);
262 # add "$Config{installarchlib}/CORE" to default search path
263 push @libpath, "$Config{installarchlib}/CORE";
265 if ($VC and exists $ENV{LIB} and $ENV{LIB}) {
266 push @libpath, split /;/, $ENV{LIB};
269 foreach (Text::ParseWords::quotewords('\s+', 0, $potential_libs)){
273 # see if entry is a flag
275 $search = 0 if lc eq ':nosearch';
276 $search = 1 if lc eq ':search';
277 warn "Ignoring unknown flag '$thislib'\n"
278 if $verbose and !/^:(no)?(search|default)$/i;
282 # if searching is disabled, do compiler-specific translations
284 s/^-l(.+)$/$1.lib/ unless $GC;
285 s/^-L/-libpath:/ if $VC;
286 push(@extralibs, $_);
291 # handle possible linker path arguments
292 if (s/^-L// and not -d) {
293 warn "$thislib ignored, directory does not exist\n"
298 unless ($self->file_name_is_absolute($_)) {
299 warn "Warning: '$thislib' changed to '-L$pwd/$_'\n";
300 $_ = $self->catdir($pwd,$_);
302 push(@searchpath, $_);
306 # handle possible library arguments
307 if (s/^-l// and $GC and !/^lib/i) {
310 $_ .= $libext if !/\Q$libext\E$/i;
315 # look for the file itself
317 warn "'$thislib' found as '$_'\n" if $verbose;
319 push(@extralibs, $_);
324 foreach $thispth (@searchpath, @libpath){
325 unless (-f ($fullname="$thispth\\$_")) {
326 warn "'$thislib' not found as '$fullname'\n" if $verbose;
329 warn "'$thislib' found as '$fullname'\n" if $verbose;
332 push(@extralibs, $fullname);
333 push @libs, $fullname unless $libs_seen{$fullname}++;
337 # do another pass with (or without) leading 'lib' if they used -l
338 if (!$found_lib and $thislib =~ /^-l/ and !$secondpass++) {
340 goto LOOKAGAIN if s/^lib//i;
349 warn "Note (probably harmless): "
350 ."No library found for '$thislib'\n"
355 return ('','','','', ($give_libs ? \@libs : ())) unless $found;
357 # make sure paths with spaces are properly quoted
358 @extralibs = map { (/\s/ && !/^".*"$/) ? qq["$_"] : $_ } @extralibs;
359 @libs = map { (/\s/ && !/^".*"$/) ? qq["$_"] : $_ } @libs;
360 $lib = join(' ',@extralibs);
362 # normalize back to backward slashes (to help braindead tools)
363 # XXX this may break equally braindead GNU tools that don't understand
364 # backslashes, either. Seems like one can't win here. Cursed be CP/M.
367 warn "Result: $lib\n" if $verbose;
368 wantarray ? ($lib, '', $lib, '', ($give_libs ? \@libs : ())) : $lib;
373 my($self, $potential_libs,$verbose,$give_libs) = @_;
375 my($dbgqual) = $self->{OPTIMIZE} || $Config{'optimize'} ||
376 $self->{CCFLAS} || $Config{'ccflags'};
377 @crtls = ( ($dbgqual =~ m-/Debug-i ? $Config{'dbgprefix'} : '')
379 push(@crtls, grep { not /\(/ } split /\s+/, $Config{'perllibs'});
380 push(@crtls, grep { not /\(/ } split /\s+/, $Config{'libc'});
381 # In general, we pass through the basic libraries from %Config unchanged.
382 # The one exception is that if we're building in the Perl source tree, and
383 # a library spec could be resolved via a logical name, we go to some trouble
384 # to insure that the copy in the local tree is used, rather than one to
385 # which a system-wide logical may point.
386 if ($self->{PERL_SRC}) {
387 my($lib,$locspec,$type);
388 foreach $lib (@crtls) {
389 if (($locspec,$type) = $lib =~ m-^([\w$\-]+)(/\w+)?- and $locspec =~ /perl/i) {
390 if (lc $type eq '/share') { $locspec .= $Config{'exe_ext'}; }
391 elsif (lc $type eq '/library') { $locspec .= $Config{'lib_ext'}; }
392 else { $locspec .= $Config{'obj_ext'}; }
393 $locspec = $self->catfile($self->{PERL_SRC},$locspec);
394 $lib = "$locspec$type" if -e $locspec;
398 $crtlstr = @crtls ? join(' ',@crtls) : '';
400 unless ($potential_libs) {
401 warn "Result:\n\tEXTRALIBS: \n\tLDLOADLIBS: $crtlstr\n" if $verbose;
402 return ('', '', $crtlstr, '', ($give_libs ? [] : ()));
405 my(@dirs,@libs,$dir,$lib,%found,@fndlibs,$ldlib);
407 my($so,$lib_ext,$obj_ext) = @Config{'so','lib_ext','obj_ext'};
408 # List of common Unix library names and there VMS equivalents
409 # (VMS equivalent of '' indicates that the library is automatially
410 # searched by the linker, and should be skipped here.)
411 my(@flibs, %libs_seen);
412 my %libmap = ( 'm' => '', 'f77' => '', 'F77' => '', 'V77' => '', 'c' => '',
413 'malloc' => '', 'crypt' => '', 'resolv' => '', 'c_s' => '',
414 'socket' => '', 'X11' => 'DECW$XLIBSHR',
415 'Xt' => 'DECW$XTSHR', 'Xm' => 'DECW$XMLIBSHR',
416 'Xmu' => 'DECW$XMULIBSHR');
417 if ($Config{'vms_cc_type'} ne 'decc') { $libmap{'curses'} = 'VAXCCURSE'; }
419 warn "Potential libraries are '$potential_libs'\n" if $verbose;
421 # First, sort out directories and library names in the input
422 foreach $lib (split ' ',$potential_libs) {
423 push(@dirs,$1), next if $lib =~ /^-L(.*)/;
424 push(@dirs,$lib), next if $lib =~ /[:>\]]$/;
425 push(@dirs,$lib), next if -d $lib;
426 push(@libs,$1), next if $lib =~ /^-l(.*)/;
429 push(@dirs,split(' ',$Config{'libpth'}));
431 # Now make sure we've got VMS-syntax absolute directory specs
432 # (We don't, however, check whether someone's hidden a relative
433 # path in a logical name.)
434 foreach $dir (@dirs) {
436 warn "Skipping nonexistent Directory $dir\n" if $verbose > 1;
440 warn "Resolving directory $dir\n" if $verbose;
441 if ($self->file_name_is_absolute($dir)) { $dir = $self->fixpath($dir,1); }
442 else { $dir = $self->catdir($cwd,$dir); }
444 @dirs = grep { length($_) } @dirs;
445 unshift(@dirs,''); # Check each $lib without additions first
447 LIB: foreach $lib (@libs) {
448 if (exists $libmap{$lib}) {
449 next unless length $libmap{$lib};
450 $lib = $libmap{$lib};
453 my(@variants,$variant,$name,$test,$cand);
456 # If we don't have a file type, consider it a possibly abbreviated name and
457 # check for common variants. We try these first to grab libraries before
458 # a like-named executable image (e.g. -lperl resolves to perlshr.exe
460 if ($lib !~ /\.[^:>\]]*$/) {
461 push(@variants,"${lib}shr","${lib}rtl","${lib}lib");
462 push(@variants,"lib$lib") if $lib !~ /[:>\]]/;
464 push(@variants,$lib);
465 warn "Looking for $lib\n" if $verbose;
466 foreach $variant (@variants) {
467 foreach $dir (@dirs) {
470 $name = "$dir$variant";
471 warn "\tChecking $name\n" if $verbose > 2;
472 if (-f ($test = VMS::Filespec::rmsexpand($name))) {
473 # It's got its own suffix, so we'll have to figure out the type
474 if ($test =~ /(?:$so|exe)$/i) { $type = 'SHR'; }
475 elsif ($test =~ /(?:$lib_ext|olb)$/i) { $type = 'OLB'; }
476 elsif ($test =~ /(?:$obj_ext|obj)$/i) {
477 warn "Note (probably harmless): "
478 ."Plain object file $test found in library list\n";
482 warn "Note (probably harmless): "
483 ."Unknown library type for $test; assuming shared\n";
487 elsif (-f ($test = VMS::Filespec::rmsexpand($name,$so)) or
488 -f ($test = VMS::Filespec::rmsexpand($name,'.exe'))) {
490 $name = $test unless $test =~ /exe;?\d*$/i;
492 elsif (not length($ctype) and # If we've got a lib already, don't bother
493 ( -f ($test = VMS::Filespec::rmsexpand($name,$lib_ext)) or
494 -f ($test = VMS::Filespec::rmsexpand($name,'.olb')))) {
496 $name = $test unless $test =~ /olb;?\d*$/i;
498 elsif (not length($ctype) and # If we've got a lib already, don't bother
499 ( -f ($test = VMS::Filespec::rmsexpand($name,$obj_ext)) or
500 -f ($test = VMS::Filespec::rmsexpand($name,'.obj')))) {
501 warn "Note (probably harmless): "
502 ."Plain object file $test found in library list\n";
504 $name = $test unless $test =~ /obj;?\d*$/i;
507 $ctype = $type; $cand = $name;
508 last if $ctype eq 'SHR';
512 # This has to precede any other CRTLs, so just make it first
513 if ($cand eq 'VAXCCURSE') { unshift @{$found{$ctype}}, $cand; }
514 else { push @{$found{$ctype}}, $cand; }
515 warn "\tFound as $cand (really $test), type $ctype\n" if $verbose > 1;
516 push @flibs, $name unless $libs_seen{$fullname}++;
520 warn "Note (probably harmless): "
521 ."No library found for $lib\n";
524 push @fndlibs, @{$found{OBJ}} if exists $found{OBJ};
525 push @fndlibs, map { "$_/Library" } @{$found{OLB}} if exists $found{OLB};
526 push @fndlibs, map { "$_/Share" } @{$found{SHR}} if exists $found{SHR};
527 $lib = join(' ',@fndlibs);
529 $ldlib = $crtlstr ? "$lib $crtlstr" : $lib;
530 warn "Result:\n\tEXTRALIBS: $lib\n\tLDLOADLIBS: $ldlib\n" if $verbose;
531 wantarray ? ($lib, '', $ldlib, '', ($give_libs ? \@flibs : ())) : $lib;
540 ExtUtils::Liblist - determine libraries to use and how to use them
544 C<require ExtUtils::Liblist;>
546 C<ExtUtils::Liblist::ext($self, $potential_libs, $verbose, $need_names);>
550 This utility takes a list of libraries in the form C<-llib1 -llib2
551 -llib3> and returns lines suitable for inclusion in an extension
552 Makefile. Extra library paths may be included with the form
553 C<-L/another/path> this will affect the searches for all subsequent
556 It returns an array of four or five scalar values: EXTRALIBS,
557 BSLOADLIBS, LDLOADLIBS, LD_RUN_PATH, and, optionally, a reference to
558 the array of the filenames of actual libraries. Some of these don't
559 mean anything unless on Unix. See the details about those platform
560 specifics below. The list of the filenames is returned only if
561 $need_names argument is true.
563 Dependent libraries can be linked in one of three ways:
567 =item * For static extensions
569 by the ld command when the perl binary is linked with the extension
570 library. See EXTRALIBS below.
572 =item * For dynamic extensions
574 by the ld command when the shared object is built/linked. See
577 =item * For dynamic extensions
579 by the DynaLoader when the shared object is loaded. See BSLOADLIBS
586 List of libraries that need to be linked with when linking a perl
587 binary which includes this extension. Only those libraries that
588 actually exist are included. These are written to a file and used
591 =head2 LDLOADLIBS and LD_RUN_PATH
593 List of those libraries which can or must be linked into the shared
594 library when created using ld. These may be static or dynamic
595 libraries. LD_RUN_PATH is a colon separated list of the directories
596 in LDLOADLIBS. It is passed as an environment variable to the process
597 that links the shared library.
601 List of those libraries that are needed but can be linked in
602 dynamically at run time on this platform. SunOS/Solaris does not need
603 this because ld records the information (from LDLOADLIBS) into the
604 object file. This list is used to create a .bs (bootstrap) file.
608 This module deals with a lot of system dependencies and has quite a
609 few architecture specific C<if>s in the code.
611 =head2 VMS implementation
613 The version of ext() which is executed under VMS differs from the
614 Unix-OS/2 version in several respects:
620 Input library and path specifications are accepted with or without the
621 C<-l> and C<-L> prefixes used by Unix linkers. If neither prefix is
622 present, a token is considered a directory to search if it is in fact
623 a directory, and a library to search for otherwise. Authors who wish
624 their extensions to be portable to Unix or OS/2 should use the Unix
625 prefixes, since the Unix-OS/2 version of ext() requires them.
629 Wherever possible, shareable images are preferred to object libraries,
630 and object libraries to plain object files. In accordance with VMS
631 naming conventions, ext() looks for files named I<lib>shr and I<lib>rtl;
632 it also looks for I<lib>lib and libI<lib> to accommodate Unix conventions
633 used in some ported software.
637 For each library that is found, an appropriate directive for a linker options
638 file is generated. The return values are space-separated strings of
639 these directives, rather than elements used on the linker command line.
643 LDLOADLIBS contains both the libraries found based on C<$potential_libs> and
644 the CRTLs, if any, specified in Config.pm. EXTRALIBS contains just those
645 libraries found based on C<$potential_libs>. BSLOADLIBS and LD_RUN_PATH
650 In addition, an attempt is made to recognize several common Unix library
651 names, and filter them out or convert them to their VMS equivalents, as
654 In general, the VMS version of ext() should properly handle input from
655 extensions originally designed for a Unix or VMS environment. If you
656 encounter problems, or discover cases where the search could be improved,
659 =head2 Win32 implementation
661 The version of ext() which is executed under Win32 differs from the
662 Unix-OS/2 version in several respects:
668 If C<$potential_libs> is empty, the return value will be empty.
669 Otherwise, the libraries specified by C<$Config{perllibs}> (see Config.pm)
670 will be appended to the list of C<$potential_libs>. The libraries
671 will be searched for in the directories specified in C<$potential_libs>,
672 C<$Config{libpth}>, and in C<$Config{installarchlib}/CORE>.
673 For each library that is found, a space-separated list of fully qualified
674 library pathnames is generated.
678 Input library and path specifications are accepted with or without the
679 C<-l> and C<-L> prefixes used by Unix linkers.
681 An entry of the form C<-La:\foo> specifies the C<a:\foo> directory to look
682 for the libraries that follow.
684 An entry of the form C<-lfoo> specifies the library C<foo>, which may be
685 spelled differently depending on what kind of compiler you are using. If
686 you are using GCC, it gets translated to C<libfoo.a>, but for other win32
687 compilers, it becomes C<foo.lib>. If no files are found by those translated
688 names, one more attempt is made to find them using either C<foo.a> or
689 C<libfoo.lib>, depending on whether GCC or some other win32 compiler is
690 being used, respectively.
692 If neither the C<-L> or C<-l> prefix is present in an entry, the entry is
693 considered a directory to search if it is in fact a directory, and a
694 library to search for otherwise. The C<$Config{lib_ext}> suffix will
695 be appended to any entries that are not directories and don't already have
698 Note that the C<-L> and C<-l> prefixes are B<not required>, but authors
699 who wish their extensions to be portable to Unix or OS/2 should use the
700 prefixes, since the Unix-OS/2 version of ext() requires them.
704 Entries cannot be plain object files, as many Win32 compilers will
705 not handle object files in the place of libraries.
709 Entries in C<$potential_libs> beginning with a colon and followed by
710 alphanumeric characters are treated as flags. Unknown flags will be ignored.
712 An entry that matches C</:nodefault/i> disables the appending of default
713 libraries found in C<$Config{perllibs}> (this should be only needed very rarely).
715 An entry that matches C</:nosearch/i> disables all searching for
716 the libraries specified after it. Translation of C<-Lfoo> and
717 C<-lfoo> still happens as appropriate (depending on compiler being used,
718 as reflected by C<$Config{cc}>), but the entries are not verified to be
719 valid files or directories.
721 An entry that matches C</:search/i> reenables searching for
722 the libraries specified after it. You can put it at the end to
723 enable searching for default libraries specified by C<$Config{perllibs}>.
727 The libraries specified may be a mixture of static libraries and
728 import libraries (to link with DLLs). Since both kinds are used
729 pretty transparently on the Win32 platform, we do not attempt to
730 distinguish between them.
734 LDLOADLIBS and EXTRALIBS are always identical under Win32, and BSLOADLIBS
735 and LD_RUN_PATH are always empty (this may change in future).
739 You must make sure that any paths and path components are properly
740 surrounded with double-quotes if they contain spaces. For example,
741 C<$potential_libs> could be (literally):
743 "-Lc:\Program Files\vc\lib" msvcrt.lib "la test\foo bar.lib"
745 Note how the first and last entries are protected by quotes in order
746 to protect the spaces.
750 Since this module is most often used only indirectly from extension
751 C<Makefile.PL> files, here is an example C<Makefile.PL> entry to add
752 a library to the build process for an extension:
756 When using GCC, that entry specifies that MakeMaker should first look
757 for C<libgl.a> (followed by C<gl.a>) in all the locations specified by
760 When using a compiler other than GCC, the above entry will search for
761 C<gl.lib> (followed by C<libgl.lib>).
763 If the library happens to be in a location not in C<$Config{libpth}>,
766 LIBS => ['-Lc:\gllibs -lgl']
768 Here is a less often used example:
770 LIBS => ['-lgl', ':nosearch -Ld:\mesalibs -lmesa -luser32']
772 This specifies a search for library C<gl> as before. If that search
773 fails to find the library, it looks at the next item in the list. The
774 C<:nosearch> flag will prevent searching for the libraries that follow,
775 so it simply returns the value as C<-Ld:\mesalibs -lmesa -luser32>,
776 since GCC can use that value as is with its linker.
778 When using the Visual C compiler, the second item is returned as
779 C<-libpath:d:\mesalibs mesa.lib user32.lib>.
781 When using the Borland compiler, the second item is returned as
782 C<-Ld:\mesalibs mesa.lib user32.lib>, and MakeMaker takes care of
783 moving the C<-Ld:\mesalibs> to the correct place in the linker
791 L<ExtUtils::MakeMaker>