File Coverage

blib/lib/ExtUtils/F77.pm

Criterion	Covered	Total	%
statement	58	182	31.8
branch	22	90	24.4
condition	4	42	9.5
subroutine	7	17	41.1
pod	6	13	46.1
total	97	344	28.2

package ExtUtils::F77;

use Config;
use File::Spec;

=head1 NAME

ExtUtils::F77 - Simple interface to F77 libs

=head1 DESCRIPTION

This module tries to figure out how to link C programs with
Fortran subroutines on your system. Basically one must add a list
of Fortran runtime libraries. The problem is their location
and name varies with each OS/compiler combination!

This module tries to implement a simple
'rule-of-thumb' database for various flavours of UNIX systems.
A simple self-documenting Perl database of knowledge/code
for figuring out how to link for various combinations of OS and
compiler is embedded in the modules Perl code. Please help
save the world by sending database entries for
your system to [e-mail]

Note the default on most systems is now to search for a generic 'GNU' compiler
which can be g77, gfortran or g95 and then find the appropriate link
libraries automatically. (This is the 'Generic' 'GNU' database entry
in the code.)

The library list which the module returns
can be explicitly overridden by setting the environment
variable F77LIBS, e.g.

  % setenv F77LIBS "-lfoo -lbar"
  % perl Makefile.PL
  ...

=cut

$VERSION = "1.19_3";

warn "\nExtUtils::F77: Version $VERSION\n";

# Database starts here. Basically we have a large hash specifying
# entries for each os/compiler combination. Entries can be code refs
# in which case they are executed and the returned value used. This
# allows us to be quite smart.

# Hash key convention is uppercase first letter of
# hash keys. First key is usually the name of the architecture as
# returned by Config (modulo ucfirst()).

print "Loaded ExtUtils::F77 version $VERSION\n";

%F77config=();

########## Win32 Specific ##############

if ($^O =~ /MSWin/i) {
   my @version;
   if ($Config{cc} =~ /x86_64\-w64\-mingw32\-gcc/) {
      # This must be gcc-4.x.x
      $gcc = 'x86_64-w64-mingw32-gcc';
      $gfortran = 'x86_64-w64-mingw32-gfortran';
      $fallback_compiler = 'GFortran';
   }
   elsif ($Config{gccversion}) {
      # Different fortran compiler for gcc-4.x.x (and later) versus gcc-3.x.x
      $gcc = 'gcc';
      @version = split /\./, $Config{gccversion};
      $fallback_compiler = $version[0] >= 4 ? 'GFortran' : 'G77';
      $gfortran = 'gfortran';
   }
   else {
      $gcc = 'gcc';
      $gfortran = 'gfortran';
      $fallback_compiler = 'G77';
   }
}
else {
   # No change from version 1.16.
   $gcc = 'gcc';
   $gfortran = 'gfortran';
   $fallback_compiler = 'G77';
}

############## End of Win32 Specific ##############

$F77config{MinGW}{G77}{Link} = sub {
   my @libs = ('g2c', 'f2c');
   my ($dir, $lib, $test);
   foreach $test (@libs) {
      $dir = `g77 -print-file-name=lib$test.a`;
      chomp $dir;
      # Note that -print-file-name returns just the library name
      # if it cant be found - make sure that we only accept the
      # directory if it returns a proper path (or matches a /)
      if (defined $dir && $dir ne "lib$test.a") {
         $lib = $test; # Found an existing library
         last;
      }
   }

   if ( defined $dir  && defined $lib) {
      $dir =~ s,/lib$lib.a$,,;
   } else {
      $dir = "/usr/local/lib";
      $lib = "f2c";
   }
   return( "-L$dir -L/usr/lib -l$lib -lm" );
};

$F77config{MinGW}{GFortran}{Link} = sub {
   $dir = `$gfortran -print-file-name=libgfortran.a`;
   chomp $dir;
   # Note that -print-file-name returns just the library name
   # if it cant be found - make sure that we only accept the
   # directory if it returns a proper path (or matches a /)

   if ( defined $dir ) {
      $dir =~ s,/libgfortran.a$,,;
   } else {
      $dir = "/usr/local/lib";
   }
   return( "-L$dir -L/usr/lib -lgfortran -lquadmath -lm" );
};

$F77config{MinGW}{G77}{Trail_} = 1;
$F77config{MinGW}{GFortran}{Trail_} = 1;
$F77config{MinGW}{G77}{Compiler} = find_in_path('g77','f77','fort77');
$F77config{MinGW}{GFortran}{Compiler} = "$gfortran";
$F77config{MinGW}{G77}{Cflags} = '-O';
$F77config{MinGW}{GFortran}{Cflags}   = '-O';

### SunOS (use this as a template for new entries) ###

# Code to figure out and return link-string for this architecture
# Returns false if it can't find anything sensible.

$F77config{Sunos}{F77}{Link} = sub {
   $dir = find_highest_SC("/usr/lang/SC*");
   return "" unless $dir; # Failure
   print "$Pkg: Found Fortran latest version lib dir $dir\n";
   return "-L$dir -lF77 -lm";
};

# Whether symbols (subroutine names etc.) have trailing underscores
# (true/false)

$F77config{Sunos}{F77}{Trail_} = 1;

# Name of default compiler - corresponds to one of the above keys

$F77config{Sunos}{DEFAULT} = 'F77';

# Program to run to actually compile stuff

$F77config{Sunos}{F77}{Compiler} = 'f77';

# Associated compiler flags

$F77config{Sunos}{F77}{Cflags} = '-O';

############ Rest of database is here ############

### Solaris ###

$F77config{Solaris}{F77}{Link} = sub {
   my $NSPATH;
   my $dir;

   #find the SUNWspro entry of nonstandard inst. in LD_LIBRARY_PATH
   if ( defined $ENV{'LD_LIBRARY_PATH'} &&
      $ENV{'LD_LIBRARY_PATH'} =~ m{([^:]*SUNWspro[^/]*)} )
   {
      $NSPATH = $1;
   }

   elsif ( defined $ENV{'PATH'} ) {

      foreach ( split (/:/,$ENV{PATH}) ) {
         if ( m{(.*SUNWspro[^/]*)} ) {
            $NSPATH = $1;
            last;
         }
      }
   }


   if (defined $NSPATH) {

      print "$Pkg: Found F77 path:--->$NSPATH\n";

      $dir = find_highest_SC("$NSPATH/WS*/lib") ||
      find_highest_SC("$NSPATH/SC*/lib") ||
      find_highest_SC("$NSPATH/sunwspro*/SUNWspro/SC*/lib");

      # that failed.  try $NSPATH/lib. use glob to
      # match for libF77.*, as libF77.a isn't there anymore?
      unless ( $dir )
      {
         print "$Pkg: Trying $NSPATH/lib\n";
         $dir = "$NSPATH/lib" if glob("$NSPATH/lib/libF77*");
      }

   } else {
   }
   return "" unless $dir; # Failure
   print "$Pkg: Found Fortran latest version lib dir $dir\n";

   my @libs;

   # determine libraries. F77 and M77 aren't available in the latest
   # compilers
   my $vcruft = qx/$F77config{Solaris}{F77}{Compiler} -V 2>&1/;
   if ( $vcruft =~ /Forte Developer 7/
      || $vcruft =~ /f90:/
   )
   {
      push @libs, qw/
      -lf77compat
      -lfui
      -lfai
      -lfai2
      -lfsumai
      -lfprodai
      -lfminlai
      -lfmaxlai
      -lfminvai
      -lfmaxvai
      -lfsu
      -lsunmath
      -lm
      /;
   }
   else
   {
      push @libs, qw/
      -lF77
      -lM77
      -lsunmath
      -lm
      /;
   }

   join( ' ', "-L$dir", @libs );
};


$F77config{Solaris}{F77}{Trail_} = 1;
$F77config{Solaris}{F77}{Compiler} = 'f77';
$F77config{Solaris}{F77}{Cflags} = '-O';
$F77config{Solaris}{DEFAULT} = 'F77';

### Generic GNU-77 or F2C system ###

$F77config{Generic}{GNU}{Trail_} = 1;
$F77config{Generic}{GNU}{Cflags} = ' ';        # <---need this space!
$F77config{Generic}{GNU}{Link}   = link_gnufortran_compiler('g77', 'gfortran', 'g95', 'fort77');
$F77config{Generic}{GNU}{Compiler} = find_in_path('g77', "$gfortran", 'g95','fort77');
$F77config{Generic}{DEFAULT}     = 'GNU';

### cygwin ###

$F77config{Cygwin}{GNU}{Trail_} = 1;
$F77config{Cygwin}{GNU}{Cflags} = '-O';        # <---need this space!
$F77config{Cygwin}{GNU}{Link}   = link_gnufortran_compiler('g77', 'gfortran', 'g95', 'fort77');
$F77config{Cygwin}{GNU}{Compiler} = find_in_path('g77', "$gfortran", 'g95','fort77');
$F77config{Cygwin}{DEFAULT}     = 'GNU';

### Linux ###

$F77config{Linux}{GNU}     = $F77config{Generic}{GNU};
$F77config{Linux}{DEFAULT} = 'GNU';

### DEC OSF/1 ###

$F77config{Dec_osf}{F77}{Link}   = "-L/usr/lib -lUfor -lfor -lFutil -lm -lots -lc";
$F77config{Dec_osf}{F77}{Trail_} = 1;
$F77config{Dec_osf}{F77}{Compiler} = 'f77';
$F77config{Dec_osf}{F77}{Cflags} = '-O';
$F77config{Dec_osf}{DEFAULT}     = 'F77';

### HP/UX ###

$F77config{Hpux}{F77}{Link}   = "-L/usr/lib -lcl -lm";
$F77config{Hpux}{F77}{Trail_} = 0;
$F77config{Hpux}{F77}{Compiler} = 'f77';
$F77config{Hpux}{F77}{Cflags} = '-O';
$F77config{Hpux}{DEFAULT}     = 'F77';

### IRIX ###

# From: Ovidiu Toader
# For an SGI running IRIX 6.4 or higher (probably lower than 6.4 also)
# there is a new abi, -64, which produces 64 bit executables. This is no
# longer an experimental feature and I am using it exclusively without any
# problem. The code below is what I use instead of original IRIX section
# in the ExtUtils::F77 package. It adds the -64 flag and it is supposed to
# provide the same functionality as the old code for a non -64 abi.

if (ucfirst($Config{'osname'}) eq "Irix")
{
   my ($cflags,$mips,$default_abi,$abi,$mips_dir,$libs);
   $cflags = $Config{cc};
   ($mips) = ($cflags =~ /(-mips\d)/g);
   $mips = "" if ! defined($mips);
   $mips_dir = $mips;$mips_dir =~ s/-//g;
   $default_abi = $Config{osvers} >= 6.4 ? "-n32" : "-o32";
   GET_ABI:
   {
      # -32 seems to be synonymous for -o32 (CS)
      $abi = "-o32",last GET_ABI if $cflags =~ /-o?32/;
      $abi = "-n32",last GET_ABI if $cflags =~ /-n32/;
      $abi = "-64",last GET_ABI if $cflags =~ /-64/;
      $abi = $default_abi;
   }
   if ( $abi eq "-64" ){
      $libs = ( (-r "/usr/lib64/$mips_dir") && (-d _) && (-x _) ) ?
      "-L/usr/lib64/$mips_dir" : "";
      $libs .=  " -L/usr/lib64 -lfortran -lm";
   }
   if ( $abi eq "-n32" ){
      $libs = ( (-r "/usr/lib32/$mips_dir") && (-d _) && (-x _) ) ?
      "-L/usr/lib32/$mips_dir" : "";
      $libs .=  " -L/usr/lib32 -lfortran -lm";
   }
   if ( $abi eq "-o32" ){
      $libs = "-L/usr/lib -lF77 -lI77 -lU77 -lisam -lm";
   }
   $F77config{Irix}{F77}{Cflags}   = "$abi $mips";
   $F77config{Irix}{F77}{Link}     = "$libs";
   $F77config{Irix}{F77}{Trail_}   = 1;
   $F77config{Irix}{F77}{Compiler} = "f77 $abi";
   $F77config{Irix}{DEFAULT}       = 'F77';
}

### AIX ###

$F77config{Aix}{F77}{Link}   = "-L/usr/lib -lxlf90 -lxlf -lc -lm";
$F77config{Aix}{F77}{Trail_} = 0;
$F77config{Aix}{DEFAULT}     = 'F77';

### FreeBSD ###

if($^O =~ /Freebsd/i) {
  $gfortran = 'gfortran48'; # requires rewrite
  $fallback_compiler = 'G77';
}

$F77config{Freebsd}{G77}{Link} = sub {
    $dir = `g77-34 -print-file-name=libg2c.a`;
    chomp $dir;
    # Note that -print-file-name returns just the library name
    # if it cant be found - make sure that we only accept the
    # directory if it returns a proper path (or matches a /)

    if( defined $dir ) {
        $dir =~ s,/libg2c.a$,,;
    } else {
        $dir = "/usr/local/lib";
    }
    return( "-L$dir -L/usr/lib -lg2c -lm" );
};

$F77config{Freebsd}{GFortran}{Link} = sub {
    $dir = `$gfortran -print-file-name=libgfortran.a`;
    chomp $dir;
    # Note that -print-file-name returns just the library name
    # if it cant be found - make sure that we only accept the
    # directory if it returns a proper path (or matches a /)

    if( defined $dir ) {
        $dir =~ s,/libgfortran.a$,,;
    } else {
        $dir = "/usr/local/lib";
    }
    return( "-L$dir -L/usr/lib -lgfortran -lm" );
};

$F77config{Freebsd}{G77}{Trail_} = 1;
$F77config{Freebsd}{GFortran}{Trail_} = 1;
$F77config{Freebsd}{G77}{Compiler} = 'g77-34';
$F77config{Freebsd}{GFortran}{Compiler} = "$gfortran";
$F77config{Freebsd}{G77}{Cflags} = '-O2';
$F77config{Freebsd}{GFortran}{Cflags}   = '-O2';
$F77config{Freebsd}{DEFAULT}     = 'GFortran';


### VMS ###

$F77config{VMS}{Fortran}{Trail_} = 0;
$F77config{VMS}{Fortran}{Link}   = ' ';         # <---need this space!
$F77config{VMS}{DEFAULT}     = 'Fortran';
$F77config{VMS}{Fortran}{Compiler} = 'Fortran';

### Darwin (Mac OS X) ###

$F77config{Darwin}{GNU} = $F77config{Generic}{GNU};
$F77config{Darwin}{DEFAULT}     = 'GNU';


############ End of database is here ############

=head1 SYNOPSIS

  use ExtUtils::F77;               # Automatic guess
  use ExtUtils::F77 qw(sunos);     # Specify system
  use ExtUtils::F77 qw(linux g77); # Specify system and compiler
  $fortranlibs = ExtUtils::F77->runtime;


=cut

# Package variables

$Runtime = "-LSNAFU -lwontwork";
$RuntimeOK = 0;
$Trail_  = 1;
$Pkg   = "";
$Compiler = "";
$Cflags = "";

sub get; # See below

# All the figuring out occurs during import - this is because
# a lot of the answers depend on a lot of the guesswork.

sub import {
   no warnings; # Shuts up complaints on Win32 when running PDL tests
   $Pkg    = shift;
   my $system   = ucfirst(shift);  # Set package variables
   my $compiler = ucfirst(shift);
   $Runtime = "-LSNAFU -lwontwork";

   # Guesses if system/compiler not specified.

   $system   = ucfirst $Config{'osname'} unless $system;
   $system = 'Cygwin' if $system =~ /Cygwin/;
   $compiler = get $F77config{$system}{DEFAULT} unless $compiler;

   print "$Pkg: Using system=$system compiler=" .
   (defined $compiler ? $compiler : "") . "\n";

   if (defined($ENV{F77LIBS})) {
      print "Overriding Fortran libs from value of enviroment variable F77LIBS = $ENV{F77LIBS}\n";
      $Runtime = $ENV{F77LIBS};
   }
   else {

      # Try this combination

      if ( defined( $compiler ) and defined( $F77config{$system} )){
         my $flibs = get ($F77config{$system}{$compiler}{Link});
         if ($flibs ne "") {
            $Runtime = $flibs;# . gcclibs();
            # We don't want to append gcc libs if we are using
            # non gnu compilers. Initially, explicitly check for
            # use of sun compiler
            #$Runtime .= gcclibs($flibs) unless $flibs =~ /sunmath/;
            #(Note appending gcclibs seems to be no longer required)
            $Runtime =~ s|L([a-z,A-Z]):|L//$1|g if $^O =~ /cygwin/i;
            $Runtime = ' ' if $^O eq 'VMS';  # <-- need this space!
            print "Runtime: $Runtime\n";
            $ok = 1;
            if ($compiler eq 'GNU') { # Special gfortran case since it seems to have lots of random libs
               print "Found compiler=$compiler - skipping validation of $Runtime \n";

            }else {
               $ok = validate_libs($Runtime) if $flibs ne "" ;
            }
         }
      }else {
         $Runtime = $ok = "";
      }

      # If it doesn't work try Generic + GNU77

      unless (("$Runtime" ne "-LSNAFU -lwontwork") && $ok) {
         print <<"EOD";
         $Pkg: Unable to guess and/or validate system/compiler configuration
         $Pkg: Will try system=Generic Compiler=$fallback_compiler
EOD
         $system   =
         $Config{cc} =~ /\bgcc/ && $^O =~ /MSWin32/i ? "MinGW"
                                 : $^O =~ /Freebsd/i ? "Freebsd"
         :"Generic";
         $compiler = $fallback_compiler;
         my $flibs = get ($F77config{$system}{$compiler}{Link});
         $Runtime =  $flibs ; #. gcclibs($flibs); #  Note gcclibs appears to be no longer required.
         $ok = validate_libs($Runtime) if $flibs ne "";
         print "$Pkg: Well that didn't appear to validate. Well I will try it anyway.\n"
         unless $Runtime && $ok;
      }

      $RuntimeOK = $ok;

   } # Not overriding

   # Now get the misc info for the methods.

   if (defined( $F77config{$system}{$compiler}{Trail_} )){
      $Trail_  = get $F77config{$system}{$compiler}{Trail_};
   }
   else{
      print << "EOD";
      $Pkg: There does not appear to be any configuration info about
      $Pkg: names with trailing underscores for system $system. Will assume
      $Pkg: F77 names have trailing underscores.
EOD
      $Trail_ = 1;
   }

   if (defined( $F77config{$system}{$compiler}{Compiler} )) {
      $Compiler = get $F77config{$system}{$compiler}{Compiler};
   } else {
      print << "EOD";
      $Pkg: There does not appear to be any configuration info about
      $Pkg: the F77 compiler name. Will assume 'f77'.
EOD
      $Compiler = 'f77';
   }
   print "$Pkg: Compiler: $Compiler\n";

   if (defined( $F77config{$system}{$compiler}{Cflags} )) {
      $Cflags = get $F77config{$system}{$compiler}{Cflags} ;
   } else {
      print << "EOD";
      $Pkg: There does not appear to be any configuration info about
      $Pkg: the options for the F77 compiler. Will assume none
      $Pkg: necessary.
EOD
      $Cflags = '';
   }

   print "$Pkg: Cflags: $Cflags\n";

} # End of import ()

=head1 METHODS

The following methods are provided:

=over 4

=item * B

Returns a list of F77 runtime libraries.

  $fortranlibs = ExtUtils::F77->runtime;

=item * B

Returns TRUE only if runtime libraries have been found successfully.

=item * B

Returns true if F77 names have trailing underscores.

=item * B

Returns command to execute the compiler (e.g. 'f77').

=item * B

Returns compiler flags.

=item * B

Test to see if compiler actually works.

=back

More methods  will probably be added in the future.

=cut

sub runtime { return $Runtime; }
sub runtimeok { return $RuntimeOK; }
sub trail_  { return $Trail_; }
sub compiler { return $Compiler; }
sub cflags  { return $Cflags; }

### Minor internal utility routines ###

# Get hash entry, evaluating code references

sub get { ref($_[0]) eq "CODE" ? &{$_[0]} : $_[0] };

# Test if any files exist matching glob

sub any_exists {
   my @glob = glob(shift);
   return scalar(@glob);
}

# Find highest version number of SCN.N(.N) directories
# (Nasty SunOS/Solaris naming scheme for F77 libs]
sub find_highest_SC {
   print "$Pkg: Scanning for $_[0]\n";
   my @glob = glob(shift);
   my %n=();
   for (@glob) {
      #print "Found $_\n";
      if ( m|/SC(\d)\.(\d)/?.*$| ) {
         $n{$_} = $1 *100 + $2 * 10;
      }
      if ( m|/SC(\d)\.(\d)\.(\d)/?.*$| ) {
         $n{$_} = $1 *100 + $2 * 10 + $3;
      }
   }
   my @sorted_dirs = grep {-f "$_/libF77.a"} sort {$n{$a} <=> $n{$b}} @glob;

   return pop @sorted_dirs; # Highest N
}

# Validate a string of form "-Ldir -lfoo -lbar"

sub validate_libs {
   print "$Pkg: Validating $_[0]   ";
   my @args = split(' ',shift());
   my $pat;
   my $ret = 1;

   # Create list of directories to search (with common defaults)

   my @path = ();
   for (@args, "/usr/lib", "/lib") {
      push @path, $1 if /^-L(.+)$/ && -d $1;
   }

   # Search directories

   for (@args) {
      next if /^-L/;
      next if $_ eq "-lm"; # Ignore this common guy
      if (/^-l(.+)$/) {
         $pat = join(" ", map {$_."/lib".$1.".*"} @path); # Join dirs + file
         #print "Checking for $pat\n";
         unless (any_exists($pat)) {
            print "\n$Pkg:    Unable to find library $_" ;
            $ret = 0;
         }
      }
   }
   print $ret ? "[ok]\n" : "\n";
   return $ret;
}


sub testcompiler {

   my $file = File::Spec->tmpdir . "/testf77$$";
   $file =~ s/\\/\//g; # For Win32

   my $ret;
   open(OUT,">$file.f");
   print OUT "      print *, 'Hello World'\n";
   print OUT "      end\n";
   close(OUT);
   print "Compiling the test Fortran program...\n";
   system "$Compiler $Cflags $file.f -o ${file}_exe";
   print "Executing the test program...\n";
   if (`${file}_exe` ne " Hello World\n") {
      print "Test of Fortran Compiler FAILED. \n";
      print "Do not know how to compile Fortran on your system\n";
      $ret=0;
   }
   else{
      print "Congratulations you seem to have a working f77!\n";
      $ret=1;
   }
   unlink("${file}_exe"); unlink("$file.f"); unlink("$file.o") if -e "$file.o";
   return $ret;
};

# gcclibs() routine
#    Return gcc link libs (e.g. -L/usr/local/lib/gcc-lib/sparc-sun-sunos4.1.3_U1/2.7.0 -lgcc)
#    Note this routine appears to be no longer required - gcc3 or 4 change? - and is
#    NO LONGER CALLED from anywhere in the code. Use of this routine in the future
#    is DEPRECATED. Retain here just in case this logic is ever needed again,
#    - Karl Glazebrook Dec/2010

sub gcclibs {
   my $flibs = shift; # Fortran libs
   my $isgcc = $Config{'cc'} eq "$gcc";
   if (!$isgcc && $^O ne 'VMS') {
      print "Checking for gcc in disguise:\n";
      $isgcc = 1 if $Config{gccversion};
      my $string;
      if ($isgcc) {
         $string = "Compiler is gcc version $Config{gccversion}";
         $string .= "\n" unless $string =~ /\n$/;
      } else {
         $string = "Not gcc\n";
      }
      print $string;
   }
   if ($isgcc or ($flibs =~ /-lg2c/) or ($flibs =~ /-lf2c/) ) {
      # Don't link to libgcc on MS Windows iff we're using gfortran.
      unless($fallback_compiler eq 'GFortran' && $^O =~ /MSWin/i) {
         $gccdir = `$gcc -m32 -print-libgcc-file-name`; chomp $gccdir;
         $gccdir =~ s/\/libgcc.a//;
         return " -L$gccdir -lgcc";
      }else{
         return "";
      }

   }else{
      return "";
   }
}

# Try and find a program in the users PATH

sub find_in_path {
   my @names = @_;
   my @path;
   if ($^O =~ /mswin32/i) {
      for(@names) { $_ .= '.exe'}
      @path = split(";", $ENV{PATH});
   }
   else {@path = split(":",$ENV{PATH})}
   my ($name,$dir);
   for $name (@names) {
      return $name if exists $CACHE{$name};
      for $dir (@path) {
         if (-x $dir."/$name") {
            print "Found compiler $name\n";
            $CACHE{$name}++;
            return $name;
         }
      }
   }
   return '' if $^O eq 'VMS';
   return undef;
#   die "Unable to find a fortran compiler using names: ".join(" ",@names);
}

# Based on code from Tim Jeness, tries to figure out the correct GNU
# fortran compiler libs
sub link_gnufortran_compiler {
   return () if $^O =~ /MSWin32/i; # Unneeded for MinGW, emits warnings if allowed to proceed.
   my @try = @_;
   my $compiler = find_in_path( @try );
   # all the compilers and their libraries
   my %complibs = (
      g77 => [qw/ g2c f2c /],
      f77 => [qw/ g2c f2c /],
      fort77 => [qw/ g2c f2c /],
      gfortran => [qw/ gfortran /],
      g95 => [qw/ f95 /],
   );
   return () unless defined $compiler;
   my @libs = @{$complibs{$compiler}};
   my ($dir, $lib, $test);
   foreach $test (@libs) {
      $dir = `$compiler -print-file-name=lib$test.a`;
      chomp $dir;
      # Note that -print-file-name returns just the library name
      # if it cant be found - make sure that we only accept the
      # directory if it returns a proper path (or matches a /)
      if (defined $dir && $dir ne "lib$test.a") {
         $lib = $test; # Found an existing library
         $dir =~ s,/lib$lib.a$,,;
         last;
      } else {
         # Try the same thing again but looking for the .so file
         # rather than the .a file.
         $dir = `$compiler -print-file-name=lib$test.so`;
         chomp $dir;
         if (defined $dir && $dir ne "lib$test.so") {
            $lib = $test; # Found an existing library
            $dir =~ s,/lib$lib.so$,,;
            last;
         } else {
            $dir = "/usr/local/lib";
            $lib = "f2c";
         }
      }
   }
   # Get compiler version number
   my @t =`$compiler --version`; $t[0] =~ /(\d+).(\d)+.(\d+)/;
   my $version = "$1.$2";  # Major version number
   print "ExtUtils::F77: $compiler version $version.$3\n";
   # Sigh special case random extra gfortran libs to avoid PERL_DL_NONLAZY meltdowns. KG 25/10/2015
   $append = "";
   if ( $Config{osname} =~ /darwin/ && $Config{osvers} >= 14
      && $compiler eq 'gfortran' && $version >= 4.9 ) { # Add extra libs for gfortran versions >= 4.9 and OS X
      $append = "-lgcc_ext.10.5 -lgcc_s.10.5 -lquadmath";
      return( "-L$dir $append -L/usr/lib -l$lib -lm" );
   }
   return( "-L$dir -L/usr/lib -l$lib -lm" );
}


=head1 AUTHOR

Karl Glazebrook ([e-mail]).

=cut


1; # Return true