Created attachment 205882 [details] patch Base GCC doesn't support gnu90, but does support gnu89, which is the same.
LGTM please proceed.
A commit references this bug: Author: pkubaj Date: Tue Jul 30 12:03:43 UTC 2019 New revision: 507633 URL: https://svnweb.freebsd.org/changeset/ports/507633 Log: comms/libbtbb: fix build with GCC-based architectures Base GCC doesn't support gnu90, but does support gnu89, which is the same. PR: 239296 Approved by: gnn (maintainer), linimon (mentor) Differential Revision: https://reviews.freebsd.org/D20996 Changes: head/comms/libbtbb/files/patch-lib_CMakeLists.txt