I'm afriad I'm unable to duplicate that here. I get the warning both when I -c it, and when I run it which, as far I as I know, is the correct behavior. This is with both ActiveState perl, and Cygwin perl.

Perhaps you can post the code that's causes that behavior? You're not on 5.8.0, are you? Both of my perl's are 5.6.1. *shrug*

(Output from my test below)

bbfu
Black flowers blossum
Fearless on my breath

Hmm... a guess: my code is in a .pm file. Perhaps Perl automatically enters another "use" of import when doing a use of a module. Then the issue isn't -c or not, but main-program or not.

From your /msg, I've been able to put together the following:

[johnsca@CORY tmp]$ cat tst.pm
#!/usr/bin/perl

package tst;

use warnings;
use strict;


*import = \&foo;

sub foo {
  print "Import foo\n";
}

1;
[johnsca@CORY tmp]$ cat tst.pl
#!/usr/bin/perl

use warnings;
use strict;

use lib '.';
use tst;
[johnsca@CORY tmp]$ perl -c tst.pm
Name "tst::import" used only once: possible typo at tst.pm line 9.
tst.pm syntax OK
[johnsca@CORY tmp]$ perl -c tst.pl
Import foo
tst syntax OK
[johnsca@CORY tmp]$ perl tst.pm
Name "tst::import" used only once: possible typo at tst.pm line 9.
[johnsca@CORY tmp]$ perl tst.pl
Import foo
[download]

From this, I think makes sense. The warning when running perl -c tst.pm (and perl tst.pm) is appropriate, as import is only used once, when you consider only tst.pm. However, once you throw tst.pl into the mix, you get another (implicit) use of *tst::import via the use, as you said, which silences the warning. This makes sense as, according to the docs for use:

It is exactly equivalent to

    BEGIN { require Module; import Module LIST; }

except that Module must be a bareword.

To prevent the warning when checking tst.pm, you can locally disable warnings, as I suggested before, or you can add another (no-op) reference to *import. In the code below, I use use vars qw/*import/; because our doesn't seem to like typeglobs. :) <Update>Though our $import; seems to get rid of the error just fine.</Update>

[johnsca@CORY tmp]$ cat tst.pm
#!/usr/bin/perl

package tst;

use warnings;
use strict;


use vars qw/*import/;
# or: *import = *import;

*import = \&foo;

sub foo {
  print "Import foo\n";
}

1;
[johnsca@CORY tmp]$ perl -c tst.pm
tst.pm syntax OK
[download]

bbfu
Black flowers blossum
Fearless on my breath