Subj : src/build/Common.gmake
To   : Git commit to main/sbbs/master
From : Rob Swindell (on Debian Linux)
Date : Wed Jul 22 2026 16:22:51

https://gitlab.synchro.net/main/sbbs/-/commit/e009a5e9ae6f0ab75b933adf
Modified Files:
	src/build/Common.gmake
Log Message:
Don't leak a parent make's CFLAGS into recursive sub-makes

If CFLAGS is set in the calling environment, GNU make re-exports it to
sub-makes with whatever value the makefile has since given it.  So
sbbs3's CFLAGS -- which legitimately carries -DLINK_LIST_THREADSAFE via
XPDEV-MT_CFLAGS -- reached the "make -C ../xpdev lib" sub-make and
compiled xpdev's *single-threaded* link_list.o with the thread-safe code
paths enabled.  That object then referenced sem_trywait_block() and
pthread_mutex_initializer_np(), which are only ever built into
libxpdev_mt.a, so every utility that links plain -lxpdev (sbbsecho,
smbutil, chksmb, fixsmb, addfiles, node, ...) failed to link:

  ld: xpdev/.../libxpdev.a(link_list.o): in function `listSemTryWaitBlock':
  link_list.c: undefined reference to `sem_trywait_block'
  ld: xpdev/.../libxpdev.a(link_list.o): in function `listInit':
  link_list.c: undefined reference to `pthread_mutex_initializer_np'

Every sub-project includes build/Common.gmake and derives its own flags
from it, so inheriting the parent's was never intended -- the leaked
command line also arrived with duplicated -O3/-O2 and a doubled
-D_FORTIFY_SOURCE.  Mark the flag variables unexport so a recursive make
always starts from a clean slate.

Reported against Debian trixie, but not specific to it: reproduced (and
the fix verified) on bookworm/gcc-12 simply by putting CFLAGS in the
environment.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

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