#! perl -slw
use strict;

use Inline C => << '__C__', NAME => 'test', CLEAN_AFTER_BUILD => 0;
#include <stdio.h>

SV* test( SV *a, SV *b ) {
    if( SvREADONLY( a ) )        // Readonly? Take a copy.
        a = newSVpv( SvPVX( a ), 0 );

    if( !SvPOK( a ) && ( SvNOK( a ) || SvIOK( a ) || SvUOK( a ) ) ) // numeric
        SvPV_nolen( a );             // Force a string rep

    if( !SvPOK( a ) )      // Still nothing, must be undef?
        sv_setpv( a, "" ); // Make it the null string to stop (one possible)
        // Use of uninitialized value in subroutine entry from sv_catsv

    sv_catsv( a, b );
    return SvREFCNT_inc( a );  // Why do I need to increment the ref count?
}

__C__

print test( 'bill', 'fred' );

my( $p, $q ) = ( 'fred' );
print test( $q, $p );

$q = 'bill';
print test( $q, $p );

$q = 1;
print test( $q, $p );

$p = 1;
print test( $q, $p );

__END__
c:\test>test
billfred
fred
billfred
1fred
1fred1

##</code><code>##

SV* test( SV *a, SV *b ) {
    if( SvREADONLY( a ) )
        a = newSVpv( SvPVX( a ), 0 );
    else
       SvREFCNT_inc( a );

    if( !SvOK( a ) )
        sv_setpvn( a, "", 0 );

    sv_catsv( a, b );
    return a;
}