source: vendor/3.6.0/script/configure_check_unused.pl

#!/usr/bin/perl
# Script that finds macros in a configure script that are not 
# used in a set of C files.
# Copyright Jelmer Vernooij <jelmer@samba.org>, GPL
#
# Usage: ./$ARGV[0] configure.in [c-files...]

use strict;

sub autoconf_parse($$$$)
{
        my $in = shift;
        my $defines = shift;
        my $functions = shift;
        my $headers = shift;

        open(IN, $in) or die("Can't open $in");

        my $ln = 0;

        foreach(<IN>) {
                $ln++;

                if(/AC_DEFINE\(([^,]+),/) { 
                        $defines->{$1} = "$in:$ln";
                } 
        
                if(/AC_CHECK_FUNCS\(\[*(.[^],)]+)/) {
                        foreach(split / /, $1) { 
                                $functions->{$_} = "$in:$ln";
                        }
                }

                if(/AC_CHECK_FUNC\(([^,)]+)/) {
                        $functions->{$1} = "$in:$ln";
                }

                if(/AC_CHECK_HEADERS\(\[*([^],)]+)/) {
                        foreach(split / /, $1) { 
                                $headers->{$_} = "$in:$ln";
                        }
                }

                if(/AC_CHECK_HEADER\(([^,)]+)/) {
                        $headers->{$1} = "$in:$ln";
                }

                if(/sinclude\(([^,]+)\)/) {
                        autoconf_parse($1, $defines, $functions, $headers);
                }
        }

        close IN;
}

# Return the symbols and headers used by a C file
sub cfile_parse($$$)
{
        my $in = shift;
        my $symbols = shift;
        my $headers = shift;

        open(FI, $in) or die("Can't open $in");
        my $ln = 0;     
        my $line;
        while($line = <FI>) { 
                $ln++;
                $_ = $line;
                if (/\#([ \t]*)include ["<]([^">]+)/) { 
                        $headers->{$2} = "$in:$ln";
                }

                $_ = $line;
                while(/([A-Za-z0-9_]+)/g) { 
                        $symbols->{$1} = "$in:$ln";
                }
        }
        close FI;
}

my %ac_defines = ();
my %ac_func_checks = ();
my %ac_headers = ();
my %symbols = ();
my %headers = ();

if (scalar(@ARGV) <= 1) {
        print("Usage: configure_find_unused.pl configure.in [CFILE...]\n");
        exit 0;
}

autoconf_parse(shift(@ARGV), \%ac_defines, \%ac_func_checks, \%ac_headers);
cfile_parse($_, \%symbols, \%headers) foreach(@ARGV);

(keys %ac_defines) or warn("No defines found in configure.in file, parse error?");

foreach (keys %ac_defines) {
        if (not defined($symbols{$_})) {
                print "$ac_defines{$_}: Autoconf-defined $_ is unused\n";
        }
}

(keys %ac_func_checks) or warn("No function checks found in configure.in file, parse error?");

foreach (keys %ac_func_checks) {
        my $def = "HAVE_".uc($_);
        if (not defined($symbols{$_})) {
                print "$ac_func_checks{$_}: Autoconf-checked function `$_' is unused\n";
        } elsif (not defined($symbols{$def})) {
                print "$ac_func_checks{$_}: Autoconf-define `$def' for function `$_' is unused\n";
        }
}

(keys %ac_headers) or warn("No headers found in configure.in file, parse error?");

foreach (keys %ac_headers) {
        my $def = "HAVE_".uc($_);
        $def =~ s/[\/\.]/_/g;
        if (not defined($headers{$_})) {
                print "$ac_headers{$_}: Autoconf-checked header `$_' is unused\n";
        } elsif (not defined($symbols{$def})) {
                print "$ac_headers{$_}: Autoconf-define `$def' for header `$_' is unused\n"; 
        }
}