--- C.pm_orig	2021-12-20 22:11:48 +1100
+++ C.pm	2022-06-28 22:08:10 +1000
@@ -177,6 +177,20 @@
             $o->{ILSM}{XS}{PREFIX} = $value;
             next;
         }
+        if($key eq 'OBJECT') {
+            $o->mkpath($o->{API}{build_dir}) unless -d $o->{API}{build_dir};
+            require File::Copy;
+            $o->add_string($o->{ILSM}{MAKEFILE}, 'OBJECT', '$(O_FILES)');
+            die "'OBJECT' must specify an array reference"
+              unless ref($value) eq 'ARRAY';
+            for my $fn(@$value) {
+              File::Copy::copy("${fn}.h", $o->{API}{build_dir} . "/${fn}.h")
+                if -e "${fn}.h";
+              File::Copy::copy("${fn}.c", $o->{API}{build_dir} . "/${fn}.c")
+                if -e "${fn}.c";
+            }
+            next;
+        }
         if ($key eq 'FILTERS') {
             next if $value eq '1' or $value eq '0'; # ignore ENABLE, DISABLE
             $value = [$value] unless ref($value) eq 'ARRAY';
@@ -374,7 +388,7 @@
         open $lockfh, '>', $file or die "lockfile $file: $!";
         flock($lockfh, LOCK_EX) or die "flock: $!\n" if $^O !~ /^VMS|riscos|VOS$/;
     }
-    $o->mkpath($o->{API}{build_dir});
+    $o->mkpath($o->{API}{build_dir}) unless -d $o->{API}{build_dir};
     $o->call('preprocess', 'Build Preprocess');
     $o->call('parse', 'Build Parse');
     $o->call('write_XS', 'Build Glue 1');

##</code><code>##

OBJECT => ['./bar', './baz'],

##</code><code>##

use warnings;

use Inline C => Config =>
 BUILD_NOISY => 1,
 OBJECT => ['./bar', './baz'],
;

use Inline C =><<'EOC';

#include "bar.h"
#include "baz.h"

void foo(int i) {
  printf("bar: %d\n", bar(i));
  printf("baz: %d\n", baz(i)); 
}

EOC

foo(42);