fix: suppress uninitialized warning in pod2man when Makefile is absent

lib/ExtUtils/Command/MM.pm

@@ -146,7 +146,7 @@ sub pod2man {
 
         next if ((-e $man) &&
                  (mtime($man) > mtime($pod)) &&
-                 (mtime($man) > mtime("Makefile")));
+                 (mtime($man) > (mtime("Makefile") // 0)));
 
         my $parser = Pod::Man->new(%options);
         $parser->parse_from_file($pod, $man)

t/pod2man.t

@@ -8,7 +8,11 @@ use lib 't/lib';
 
 use ExtUtils::Command::MM;
 
-use Test::More tests => 3;
+use File::Temp qw(tempdir);
+use File::Spec;
+use Cwd qw(getcwd);
+
+use Test::More tests => 4;
 
 # The argument to perm_rw was optional.
 # [rt.cpan.org 35190]
@@ -24,6 +28,46 @@ use Test::More tests => 3;
 };
 
 
+# No "uninitialized value" warnings when Makefile does not exist (GH #479).
+# When the man page is up-to-date relative to the pod source, pod2man skips
+# regeneration by comparing mtimes.  The third comparison is against
+# "Makefile" (or the configured FIRST_MAKEFILE).  If that file does not exist,
+# mtime() returns undef and Perl emits an uninitialized-value warning.
+{
+    my $cwd = getcwd();
+    my $tmpdir = tempdir(CLEANUP => 1);
+    chdir $tmpdir or die "chdir $tmpdir: $!";
+
+    # Create a simple pod source file.
+    open my $fh, '>', 'foo.pod' or die $!;
+    print $fh "=head1 NAME\n\nfoo - test\n\n=cut\n";
+    close $fh;
+
+    # Create a man page with a future mtime so it appears up-to-date.
+    open $fh, '>', 'foo.1' or die $!;
+    print $fh "man page\n";
+    close $fh;
+
+    my $future = time() + 3600;
+    utime $future, $future, 'foo.1';
+
+    # Ensure there is no Makefile in this directory.
+    die "Unexpected Makefile in tmpdir" if -e 'Makefile';
+
+    my @warnings;
+    local $SIG{__WARN__} = sub { push @warnings, @_ };
+
+    local @ARGV = ('foo.pod', 'foo.1');
+    pod2man();
+
+    chdir $cwd or die "chdir $cwd: $!";
+
+    my @uninit = grep { /uninitialized/ } @warnings;
+    is scalar(@uninit), 0,
+        'no uninitialized-value warnings when Makefile is absent (GH #479)';
+}
+
+
 # Simulate the failure of Pod::Man loading.
 # pod2man() should react gracefully.
 {