1 package ExtUtils::Liblist;
4 # Broken out of MakeMaker from version 4.11
6 our $VERSION = substr q$Revision: 1.25 $, 10;
13 if ($^O eq 'VMS') { return &_vms_ext; }
14 elsif($^O eq 'MSWin32') { return &_win32_ext; }
15 else { return &_unix_os2_ext; }
19 my($self,$potential_libs, $verbose) = @_;
20 if ($^O =~ 'os2' and $Config{libs}) {
21 # Dynamic libraries are not transitive, so we may need including
22 # the libraries linked against perl.dll again.
24 $potential_libs .= " " if $potential_libs;
25 $potential_libs .= $Config{libs};
27 return ("", "", "", "") unless $potential_libs;
28 warn "Potential libraries are '$potential_libs':\n" if $verbose;
30 my($so) = $Config{'so'};
31 my($libs) = $Config{'libs'};
32 my $Config_libext = $Config{lib_ext} || ".a";
35 # compute $extralibs, $bsloadlibs and $ldloadlibs from
37 # this is a rewrite of Andy Dougherty's extliblist in perl
39 my(@searchpath); # from "-L/path" entries in $potential_libs
40 my(@libpath) = split " ", $Config{'libpth'};
41 my(@ldloadlibs, @bsloadlibs, @extralibs, @ld_run_path, %ld_run_path_seen);
42 my($fullname, $thislib, $thispth, @fullname);
43 my($pwd) = cwd(); # from Cwd.pm
46 foreach $thislib (split ' ', $potential_libs){
48 # Handle possible linker path arguments.
49 if ($thislib =~ s/^(-[LR])//){ # save path flag type
52 warn "$ptype$thislib ignored, directory does not exist\n"
56 unless ($self->file_name_is_absolute($thislib)) {
57 warn "Warning: $ptype$thislib changed to $ptype$pwd/$thislib\n";
58 $thislib = $self->catdir($pwd,$thislib);
60 push(@searchpath, $thislib);
61 push(@extralibs, "$ptype$thislib");
62 push(@ldloadlibs, "$ptype$thislib");
66 # Handle possible library arguments.
67 unless ($thislib =~ s/^-l//){
68 warn "Unrecognized argument in LIBS ignored: '$thislib'\n";
73 foreach $thispth (@searchpath, @libpath){
75 # Try to find the full name of the library. We need this to
76 # determine whether it's a dynamically-loadable library or not.
77 # This tends to be subject to various os-specific quirks.
78 # For gcc-2.6.2 on linux (March 1995), DLD can not load
79 # .sa libraries, with the exception of libm.sa, so we
80 # deliberately skip them.
82 $self->lsdir($thispth,"^\Qlib$thislib.$so.\E[0-9]+")){
83 # Take care that libfoo.so.10 wins against libfoo.so.9.
84 # Compare two libraries to find the most recent version
85 # number. E.g. if you have libfoo.so.9.0.7 and
86 # libfoo.so.10.1, first convert all digits into two
87 # decimal places. Then we'll add ".00" to the shorter
88 # strings so that we're comparing strings of equal length
89 # Thus we'll compare libfoo.so.09.07.00 with
90 # libfoo.so.10.01.00. Some libraries might have letters
91 # in the version. We don't know what they mean, but will
92 # try to skip them gracefully -- we'll set any letter to
93 # '0'. Finally, sort in reverse so we can take the
96 #TODO: iterate through the directory instead of sorting
98 $fullname = "$thispth/" .
101 $ma =~ tr/A-Za-z/0/s;
102 $ma =~ s/\b(\d)\b/0$1/g;
103 $mb =~ tr/A-Za-z/0/s;
104 $mb =~ s/\b(\d)\b/0$1/g;
105 while (length($ma) < length($mb)) { $ma .= ".00"; }
106 while (length($mb) < length($ma)) { $mb .= ".00"; }
107 # Comparison deliberately backwards
108 $mb cmp $ma;} @fullname)[0];
109 } elsif (-f ($fullname="$thispth/lib$thislib.$so")
110 && (($Config{'dlsrc'} ne "dl_dld.xs") || ($thislib eq "m"))){
111 } elsif (-f ($fullname="$thispth/lib${thislib}_s$Config_libext")
112 && (! $Config{'archname'} =~ /RM\d\d\d-svr4/)
113 && ($thislib .= "_s") ){ # we must explicitly use _s version
114 } elsif (-f ($fullname="$thispth/lib$thislib$Config_libext")){
115 } elsif (-f ($fullname="$thispth/$thislib$Config_libext")){
116 } elsif (-f ($fullname="$thispth/Slib$thislib$Config_libext")){
117 } elsif ($^O eq 'dgux'
118 && -l ($fullname="$thispth/lib$thislib$Config_libext")
119 && readlink($fullname) =~ /^elink:/s) {
120 # Some of DG's libraries look like misconnected symbolic
121 # links, but development tools can follow them. (They
124 # libm.a -> elink:${SDE_PATH:-/usr}/sde/\
125 # ${TARGET_BINARY_INTERFACE:-m88kdgux}/usr/lib/libm.a
127 # , the compilation tools expand the environment variables.)
129 warn "$thislib not found in $thispth\n" if $verbose;
132 warn "'-l$thislib' found at $fullname\n" if $verbose;
133 my($fullnamedir) = dirname($fullname);
134 push @ld_run_path, $fullnamedir unless $ld_run_path_seen{$fullnamedir}++;
138 # Now update library lists
140 # what do we know about this library...
141 my $is_dyna = ($fullname !~ /\Q$Config_libext\E\z/);
142 my $in_perl = ($libs =~ /\B-l\Q$ {thislib}\E\b/s);
144 # Do not add it into the list if it is already linked in
145 # with the main perl executable.
146 # We have to special-case the NeXT, because math and ndbm
147 # are both in libsys_s
149 ($Config{'osname'} eq 'next' &&
150 ($thislib eq 'm' || $thislib eq 'ndbm')) ){
151 push(@extralibs, "-l$thislib");
154 # We might be able to load this archive file dynamically
155 if ( ($Config{'dlsrc'} =~ /dl_next/ && $Config{'osvers'} lt '4_0')
156 || ($Config{'dlsrc'} =~ /dl_dld/) )
158 # We push -l$thislib instead of $fullname because
159 # it avoids hardwiring a fixed path into the .bs file.
160 # Mkbootstrap will automatically add dl_findfile() to
161 # the .bs file if it sees a name in the -l format.
162 # USE THIS, when dl_findfile() is fixed:
163 # push(@bsloadlibs, "-l$thislib");
164 # OLD USE WAS while checking results against old_extliblist
165 push(@bsloadlibs, "$fullname");
168 # For SunOS4, do not add in this shared library if
169 # it is already linked in the main perl executable
170 push(@ldloadlibs, "-l$thislib")
171 unless ($in_perl and $^O eq 'sunos');
173 push(@ldloadlibs, "-l$thislib");
176 last; # found one here so don't bother looking further
178 warn "Note (probably harmless): "
179 ."No library found for -l$thislib\n"
182 return ('','','','') unless $found;
183 ("@extralibs", "@bsloadlibs", "@ldloadlibs",join(":",@ld_run_path));
188 require Text::ParseWords;
190 my($self, $potential_libs, $verbose) = @_;
192 # If user did not supply a list, we punt.
193 # (caller should probably use the list in $Config{libs})
194 return ("", "", "", "") unless $potential_libs;
196 my $cc = $Config{cc};
197 my $VC = 1 if $cc =~ /^cl/i;
198 my $BC = 1 if $cc =~ /^bcc/i;
199 my $GC = 1 if $cc =~ /^gcc/i;
200 my $so = $Config{'so'};
201 my $libs = $Config{'libs'};
202 my $libpth = $Config{'libpth'};
203 my $libext = $Config{'lib_ext'} || ".lib";
205 if ($libs and $potential_libs !~ /:nodefault/i) {
206 # If Config.pm defines a set of default libs, we always
207 # tack them on to the user-supplied list, unless the user
208 # specified :nodefault
210 $potential_libs .= " " if $potential_libs;
211 $potential_libs .= $libs;
213 warn "Potential libraries are '$potential_libs':\n" if $verbose;
215 # normalize to forward slashes
217 $potential_libs =~ s,\\,/,g;
219 # compute $extralibs from $potential_libs
221 my @searchpath; # from "-L/path" in $potential_libs
222 my @libpath = Text::ParseWords::quotewords('\s+', 0, $libpth);
224 my $pwd = cwd(); # from Cwd.pm
228 my($fullname, $thislib, $thispth);
230 # add "$Config{installarchlib}/CORE" to default search path
231 push @libpath, "$Config{installarchlib}/CORE";
233 foreach (Text::ParseWords::quotewords('\s+', 0, $potential_libs)){
237 # see if entry is a flag
239 $search = 0 if lc eq ':nosearch';
240 $search = 1 if lc eq ':search';
241 warn "Ignoring unknown flag '$thislib'\n"
242 if $verbose and !/^:(no)?(search|default)$/i;
246 # if searching is disabled, do compiler-specific translations
248 s/^-l(.+)$/$1.lib/ unless $GC;
249 s/^-L/-libpath:/ if $VC;
250 push(@extralibs, $_);
255 # handle possible linker path arguments
256 if (s/^-L// and not -d) {
257 warn "$thislib ignored, directory does not exist\n"
262 unless ($self->file_name_is_absolute($_)) {
263 warn "Warning: '$thislib' changed to '-L$pwd/$_'\n";
264 $_ = $self->catdir($pwd,$_);
266 push(@searchpath, $_);
270 # handle possible library arguments
271 if (s/^-l// and $GC and !/^lib/i) {
274 $_ .= $libext if !/\Q$libext\E$/i;
279 # look for the file itself
281 warn "'$thislib' found as '$_'\n" if $verbose;
283 push(@extralibs, $_);
288 foreach $thispth (@searchpath, @libpath){
289 unless (-f ($fullname="$thispth\\$_")) {
290 warn "'$thislib' not found as '$fullname'\n" if $verbose;
293 warn "'$thislib' found as '$fullname'\n" if $verbose;
296 push(@extralibs, $fullname);
300 # do another pass with (or without) leading 'lib' if they used -l
301 if (!$found_lib and $thislib =~ /^-l/ and !$secondpass++) {
303 goto LOOKAGAIN if s/^lib//i;
312 warn "Note (probably harmless): "
313 ."No library found for '$thislib'\n"
318 return ('','','','') unless $found;
320 # make sure paths with spaces are properly quoted
321 @extralibs = map { (/\s/ && !/^".*"$/) ? qq["$_"] : $_ } @extralibs;
322 $lib = join(' ',@extralibs);
324 # normalize back to backward slashes (to help braindead tools)
325 # XXX this may break equally braindead GNU tools that don't understand
326 # backslashes, either. Seems like one can't win here. Cursed be CP/M.
329 warn "Result: $lib\n" if $verbose;
330 wantarray ? ($lib, '', $lib, '') : $lib;
335 my($self, $potential_libs,$verbose) = @_;
337 my($dbgqual) = $self->{OPTIMIZE} || $Config{'optimize'} ||
338 $self->{CCFLAS} || $Config{'ccflags'};
339 @crtls = ( ($dbgqual =~ m-/Debug-i ? $Config{'dbgprefix'} : '')
341 push(@crtls, grep { not /\(/ } split /\s+/, $Config{'libs'});
342 push(@crtls, grep { not /\(/ } split /\s+/, $Config{'libc'});
343 # In general, we pass through the basic libraries from %Config unchanged.
344 # The one exception is that if we're building in the Perl source tree, and
345 # a library spec could be resolved via a logical name, we go to some trouble
346 # to insure that the copy in the local tree is used, rather than one to
347 # which a system-wide logical may point.
348 if ($self->{PERL_SRC}) {
349 my($lib,$locspec,$type);
350 foreach $lib (@crtls) {
351 if (($locspec,$type) = $lib =~ m-^([\w$\-]+)(/\w+)?- and $locspec =~ /perl/i) {
352 if (lc $type eq '/share') { $locspec .= $Config{'exe_ext'}; }
353 elsif (lc $type eq '/library') { $locspec .= $Config{'lib_ext'}; }
354 else { $locspec .= $Config{'obj_ext'}; }
355 $locspec = $self->catfile($self->{PERL_SRC},$locspec);
356 $lib = "$locspec$type" if -e $locspec;
360 $crtlstr = @crtls ? join(' ',@crtls) : '';
362 unless ($potential_libs) {
363 warn "Result:\n\tEXTRALIBS: \n\tLDLOADLIBS: $crtlstr\n" if $verbose;
364 return ('', '', $crtlstr, '');
367 my(@dirs,@libs,$dir,$lib,%found,@fndlibs,$ldlib);
369 my($so,$lib_ext,$obj_ext) = @Config{'so','lib_ext','obj_ext'};
370 # List of common Unix library names and there VMS equivalents
371 # (VMS equivalent of '' indicates that the library is automatially
372 # searched by the linker, and should be skipped here.)
373 my %libmap = ( 'm' => '', 'f77' => '', 'F77' => '', 'V77' => '', 'c' => '',
374 'malloc' => '', 'crypt' => '', 'resolv' => '', 'c_s' => '',
375 'socket' => '', 'X11' => 'DECW$XLIBSHR',
376 'Xt' => 'DECW$XTSHR', 'Xm' => 'DECW$XMLIBSHR',
377 'Xmu' => 'DECW$XMULIBSHR');
378 if ($Config{'vms_cc_type'} ne 'decc') { $libmap{'curses'} = 'VAXCCURSE'; }
380 warn "Potential libraries are '$potential_libs'\n" if $verbose;
382 # First, sort out directories and library names in the input
383 foreach $lib (split ' ',$potential_libs) {
384 push(@dirs,$1), next if $lib =~ /^-L(.*)/;
385 push(@dirs,$lib), next if $lib =~ /[:>\]]$/;
386 push(@dirs,$lib), next if -d $lib;
387 push(@libs,$1), next if $lib =~ /^-l(.*)/;
390 push(@dirs,split(' ',$Config{'libpth'}));
392 # Now make sure we've got VMS-syntax absolute directory specs
393 # (We don't, however, check whether someone's hidden a relative
394 # path in a logical name.)
395 foreach $dir (@dirs) {
397 warn "Skipping nonexistent Directory $dir\n" if $verbose > 1;
401 warn "Resolving directory $dir\n" if $verbose;
402 if ($self->file_name_is_absolute($dir)) { $dir = $self->fixpath($dir,1); }
403 else { $dir = $self->catdir($cwd,$dir); }
405 @dirs = grep { length($_) } @dirs;
406 unshift(@dirs,''); # Check each $lib without additions first
408 LIB: foreach $lib (@libs) {
409 if (exists $libmap{$lib}) {
410 next unless length $libmap{$lib};
411 $lib = $libmap{$lib};
414 my(@variants,$variant,$name,$test,$cand);
417 # If we don't have a file type, consider it a possibly abbreviated name and
418 # check for common variants. We try these first to grab libraries before
419 # a like-named executable image (e.g. -lperl resolves to perlshr.exe
421 if ($lib !~ /\.[^:>\]]*$/) {
422 push(@variants,"${lib}shr","${lib}rtl","${lib}lib");
423 push(@variants,"lib$lib") if $lib !~ /[:>\]]/;
425 push(@variants,$lib);
426 warn "Looking for $lib\n" if $verbose;
427 foreach $variant (@variants) {
428 foreach $dir (@dirs) {
431 $name = "$dir$variant";
432 warn "\tChecking $name\n" if $verbose > 2;
433 if (-f ($test = VMS::Filespec::rmsexpand($name))) {
434 # It's got its own suffix, so we'll have to figure out the type
435 if ($test =~ /(?:$so|exe)$/i) { $type = 'SHR'; }
436 elsif ($test =~ /(?:$lib_ext|olb)$/i) { $type = 'OLB'; }
437 elsif ($test =~ /(?:$obj_ext|obj)$/i) {
438 warn "Note (probably harmless): "
439 ."Plain object file $test found in library list\n";
443 warn "Note (probably harmless): "
444 ."Unknown library type for $test; assuming shared\n";
448 elsif (-f ($test = VMS::Filespec::rmsexpand($name,$so)) or
449 -f ($test = VMS::Filespec::rmsexpand($name,'.exe'))) {
451 $name = $test unless $test =~ /exe;?\d*$/i;
453 elsif (not length($ctype) and # If we've got a lib already, don't bother
454 ( -f ($test = VMS::Filespec::rmsexpand($name,$lib_ext)) or
455 -f ($test = VMS::Filespec::rmsexpand($name,'.olb')))) {
457 $name = $test unless $test =~ /olb;?\d*$/i;
459 elsif (not length($ctype) and # If we've got a lib already, don't bother
460 ( -f ($test = VMS::Filespec::rmsexpand($name,$obj_ext)) or
461 -f ($test = VMS::Filespec::rmsexpand($name,'.obj')))) {
462 warn "Note (probably harmless): "
463 ."Plain object file $test found in library list\n";
465 $name = $test unless $test =~ /obj;?\d*$/i;
468 $ctype = $type; $cand = $name;
469 last if $ctype eq 'SHR';
473 # This has to precede any other CRTLs, so just make it first
474 if ($cand eq 'VAXCCURSE') { unshift @{$found{$ctype}}, $cand; }
475 else { push @{$found{$ctype}}, $cand; }
476 warn "\tFound as $cand (really $test), type $ctype\n" if $verbose > 1;
480 warn "Note (probably harmless): "
481 ."No library found for $lib\n";
484 push @fndlibs, @{$found{OBJ}} if exists $found{OBJ};
485 push @fndlibs, map { "$_/Library" } @{$found{OLB}} if exists $found{OLB};
486 push @fndlibs, map { "$_/Share" } @{$found{SHR}} if exists $found{SHR};
487 $lib = join(' ',@fndlibs);
489 $ldlib = $crtlstr ? "$lib $crtlstr" : $lib;
490 warn "Result:\n\tEXTRALIBS: $lib\n\tLDLOADLIBS: $ldlib\n" if $verbose;
491 wantarray ? ($lib, '', $ldlib, '') : $lib;
500 ExtUtils::Liblist - determine libraries to use and how to use them
504 C<require ExtUtils::Liblist;>
506 C<ExtUtils::Liblist::ext($self, $potential_libs, $verbose);>
510 This utility takes a list of libraries in the form C<-llib1 -llib2
511 -llib3> and prints out lines suitable for inclusion in an extension
512 Makefile. Extra library paths may be included with the form
513 C<-L/another/path> this will affect the searches for all subsequent
516 It returns an array of four scalar values: EXTRALIBS, BSLOADLIBS,
517 LDLOADLIBS, and LD_RUN_PATH. Some of these don't mean anything
518 on VMS and Win32. See the details about those platform specifics
521 Dependent libraries can be linked in one of three ways:
525 =item * For static extensions
527 by the ld command when the perl binary is linked with the extension
528 library. See EXTRALIBS below.
530 =item * For dynamic extensions
532 by the ld command when the shared object is built/linked. See
535 =item * For dynamic extensions
537 by the DynaLoader when the shared object is loaded. See BSLOADLIBS
544 List of libraries that need to be linked with when linking a perl
545 binary which includes this extension. Only those libraries that
546 actually exist are included. These are written to a file and used
549 =head2 LDLOADLIBS and LD_RUN_PATH
551 List of those libraries which can or must be linked into the shared
552 library when created using ld. These may be static or dynamic
553 libraries. LD_RUN_PATH is a colon separated list of the directories
554 in LDLOADLIBS. It is passed as an environment variable to the process
555 that links the shared library.
559 List of those libraries that are needed but can be linked in
560 dynamically at run time on this platform. SunOS/Solaris does not need
561 this because ld records the information (from LDLOADLIBS) into the
562 object file. This list is used to create a .bs (bootstrap) file.
566 This module deals with a lot of system dependencies and has quite a
567 few architecture specific C<if>s in the code.
569 =head2 VMS implementation
571 The version of ext() which is executed under VMS differs from the
572 Unix-OS/2 version in several respects:
578 Input library and path specifications are accepted with or without the
579 C<-l> and C<-L> prefixes used by Unix linkers. If neither prefix is
580 present, a token is considered a directory to search if it is in fact
581 a directory, and a library to search for otherwise. Authors who wish
582 their extensions to be portable to Unix or OS/2 should use the Unix
583 prefixes, since the Unix-OS/2 version of ext() requires them.
587 Wherever possible, shareable images are preferred to object libraries,
588 and object libraries to plain object files. In accordance with VMS
589 naming conventions, ext() looks for files named I<lib>shr and I<lib>rtl;
590 it also looks for I<lib>lib and libI<lib> to accommodate Unix conventions
591 used in some ported software.
595 For each library that is found, an appropriate directive for a linker options
596 file is generated. The return values are space-separated strings of
597 these directives, rather than elements used on the linker command line.
601 LDLOADLIBS contains both the libraries found based on C<$potential_libs> and
602 the CRTLs, if any, specified in Config.pm. EXTRALIBS contains just those
603 libraries found based on C<$potential_libs>. BSLOADLIBS and LD_RUN_PATH
608 In addition, an attempt is made to recognize several common Unix library
609 names, and filter them out or convert them to their VMS equivalents, as
612 In general, the VMS version of ext() should properly handle input from
613 extensions originally designed for a Unix or VMS environment. If you
614 encounter problems, or discover cases where the search could be improved,
617 =head2 Win32 implementation
619 The version of ext() which is executed under Win32 differs from the
620 Unix-OS/2 version in several respects:
626 If C<$potential_libs> is empty, the return value will be empty.
627 Otherwise, the libraries specified by C<$Config{libs}> (see Config.pm)
628 will be appended to the list of C<$potential_libs>. The libraries
629 will be searched for in the directories specified in C<$potential_libs>,
630 C<$Config{libpth}>, and in C<$Config{installarchlib}/CORE>.
631 For each library that is found, a space-separated list of fully qualified
632 library pathnames is generated.
636 Input library and path specifications are accepted with or without the
637 C<-l> and C<-L> prefixes used by Unix linkers.
639 An entry of the form C<-La:\foo> specifies the C<a:\foo> directory to look
640 for the libraries that follow.
642 An entry of the form C<-lfoo> specifies the library C<foo>, which may be
643 spelled differently depending on what kind of compiler you are using. If
644 you are using GCC, it gets translated to C<libfoo.a>, but for other win32
645 compilers, it becomes C<foo.lib>. If no files are found by those translated
646 names, one more attempt is made to find them using either C<foo.a> or
647 C<libfoo.lib>, depending on whether GCC or some other win32 compiler is
648 being used, respectively.
650 If neither the C<-L> or C<-l> prefix is present in an entry, the entry is
651 considered a directory to search if it is in fact a directory, and a
652 library to search for otherwise. The C<$Config{lib_ext}> suffix will
653 be appended to any entries that are not directories and don't already have
656 Note that the C<-L> and C<-l> prefixes are B<not required>, but authors
657 who wish their extensions to be portable to Unix or OS/2 should use the
658 prefixes, since the Unix-OS/2 version of ext() requires them.
662 Entries cannot be plain object files, as many Win32 compilers will
663 not handle object files in the place of libraries.
667 Entries in C<$potential_libs> beginning with a colon and followed by
668 alphanumeric characters are treated as flags. Unknown flags will be ignored.
670 An entry that matches C</:nodefault/i> disables the appending of default
671 libraries found in C<$Config{libs}> (this should be only needed very rarely).
673 An entry that matches C</:nosearch/i> disables all searching for
674 the libraries specified after it. Translation of C<-Lfoo> and
675 C<-lfoo> still happens as appropriate (depending on compiler being used,
676 as reflected by C<$Config{cc}>), but the entries are not verified to be
677 valid files or directories.
679 An entry that matches C</:search/i> reenables searching for
680 the libraries specified after it. You can put it at the end to
681 enable searching for default libraries specified by C<$Config{libs}>.
685 The libraries specified may be a mixture of static libraries and
686 import libraries (to link with DLLs). Since both kinds are used
687 pretty transparently on the Win32 platform, we do not attempt to
688 distinguish between them.
692 LDLOADLIBS and EXTRALIBS are always identical under Win32, and BSLOADLIBS
693 and LD_RUN_PATH are always empty (this may change in future).
697 You must make sure that any paths and path components are properly
698 surrounded with double-quotes if they contain spaces. For example,
699 C<$potential_libs> could be (literally):
701 "-Lc:\Program Files\vc\lib" msvcrt.lib "la test\foo bar.lib"
703 Note how the first and last entries are protected by quotes in order
704 to protect the spaces.
708 Since this module is most often used only indirectly from extension
709 C<Makefile.PL> files, here is an example C<Makefile.PL> entry to add
710 a library to the build process for an extension:
714 When using GCC, that entry specifies that MakeMaker should first look
715 for C<libgl.a> (followed by C<gl.a>) in all the locations specified by
718 When using a compiler other than GCC, the above entry will search for
719 C<gl.lib> (followed by C<libgl.lib>).
721 If the library happens to be in a location not in C<$Config{libpth}>,
724 LIBS => ['-Lc:\gllibs -lgl']
726 Here is a less often used example:
728 LIBS => ['-lgl', ':nosearch -Ld:\mesalibs -lmesa -luser32']
730 This specifies a search for library C<gl> as before. If that search
731 fails to find the library, it looks at the next item in the list. The
732 C<:nosearch> flag will prevent searching for the libraries that follow,
733 so it simply returns the value as C<-Ld:\mesalibs -lmesa -luser32>,
734 since GCC can use that value as is with its linker.
736 When using the Visual C compiler, the second item is returned as
737 C<-libpath:d:\mesalibs mesa.lib user32.lib>.
739 When using the Borland compiler, the second item is returned as
740 C<-Ld:\mesalibs mesa.lib user32.lib>, and MakeMaker takes care of
741 moving the C<-Ld:\mesalibs> to the correct place in the linker
749 L<ExtUtils::MakeMaker>