Created attachment 206259 [details] patch GCC9 is much more eager at defining __GNU_SOURCE, which breaks build on FreeBSD. Also add USES=sdl.
(In reply to Piotr Kubaj from comment #0) Should be fixed with https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=239648.
A commit references this bug: Author: amdmi3 Date: Wed Aug 14 16:30:12 UTC 2019 New revision: 508931 URL: https://svnweb.freebsd.org/changeset/ports/508931 Log: - Add missing USES=sdl PR: 239632 Submitted by: pkubaj@FreeBSD.org Changes: head/games/dhewm3/Makefile