In Dave's case, he's running a perl script and not building with a compiler - so it's not CPPFLAGS but rather @INC changes with perl 5.26 that he's seeing.
As always, changes are described in perldelta: http://search.cpan.org/dist/perl-5.26.0/pod/perldelta.pod#Removal_of_the_current_directory_(".")_from_@INC > On Mar 6, 2018, at 4:00 AM, Ryan Schmidt <ryandes...@macports.org> wrote: > > > On Mar 5, 2018, at 22:09, Ryan Schmidt wrote: > >> On Mar 5, 2018, at 20:06, Dave Horsfall wrote: >> >>> A script that I wrote and has worked fine for ages is now breaking with: >>> >>> Can't locate Scanner.pm in @INC (you may need to install the Scanner >>> module) (@INC contains: >>> /opt/local/lib/perl5/site_perl/5.26/darwin-thread-multi-2level >>> /opt/local/lib/perl5/site_perl/5.26 >>> /opt/local/lib/perl5/vendor_perl/5.26/darwin-thread-multi-2level >>> /opt/local/lib/perl5/vendor_perl/5.26 >>> /opt/local/lib/perl5/5.26/darwin-thread-multi-2level >>> /opt/local/lib/perl5/5.26) at ./uniscan.pl line 40. >>> BEGIN failed--compilation aborted at ./uniscan.pl line 40. >>> >>> That "Scanner.pm" module is one I wrote myself, and it's definitely there. >>> >>> No, I haven't changed anything, and it works just fine on my FreeBSD (5.24) >>> and Penguin (5.20) boxes. Older Mac versions of Perl also work (5.16, >>> 5.22, 5.24). >>> >>> Rebooted (ugh!) to eliminate a corrupted image in swap: nope. >>> >>> Uninstalled and reinstalled in case the disk binary was corrupt: nope. >>> >>> Don't tell me that Perl 5.26 comes with a built-in time-bomb... >> >> Add -I to CPPFLAGS. Perl < 5.26 did so automatically, but 5.26 no longer >> does. > > I meant: -I. > > >> See for example >> https://github.com/macports/macports-ports/commit/454eb2b0608266ab7bdf51a82d690be0f97610fe -- Daniel J. Luke