Ошибка при сборке

[IvanKayukoff]

$  uname -a
Linux dick 5.4.12-arch1-1 #1 SMP PREEMPT Tue, 14 Jan 2020 21:44:31 +0000 x86_64 GNU/Linux
$ gcc --version
gcc (GCC) 9.2.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Лог make:

$ make   
gcc --std=gnu99 -pedantic -Wall -Wextra -Werror -ggdb3 -Ilib -D_DEBUG -lncursesw -pthread -I /usr/include/ncursesw  -Wimplicit-fallthrough=0 -DPROTOCOL_VERSION=`perl -lne '$a+=$_+$. for split//;END{print$a}' src/*` -c src/config.c -o bin/config.o
In file included from src/config.c:4:
src/config.c: In function ‘config_init’:
src/config.c:248:19: error: ‘%s’ directive output may be truncated writing up to 8191 bytes into a region of size 8177 [-Werror=format-truncation=]
  248 |             warnf("[info] Config: %s: not found.", buf);
      |                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  ~~~
src/itmmorgue.h:68:34: note: in definition of macro ‘warnf’
   68 |         snprintf(___buf, BUFSIZ, fmt, __VA_ARGS__); \
      |                                  ^~~
src/config.c:248:35: note: format string is defined here
  248 |             warnf("[info] Config: %s: not found.", buf);
      |                                   ^~
In file included from src/config.c:4:
src/itmmorgue.h:68:9: note: ‘snprintf’ output between 28 and 8219 bytes into a destination of size 8192
   68 |         snprintf(___buf, BUFSIZ, fmt, __VA_ARGS__); \
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/config.c:248:13: note: in expansion of macro ‘warnf’
  248 |             warnf("[info] Config: %s: not found.", buf);
      |             ^~~~~
src/config.c:256:19: error: ‘%s’ directive output may be truncated writing up to 8191 bytes into a region of size 8177 [-Werror=format-truncation=]
  256 |             warnf("[info] Config: %s: not found.", buf);
      |                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  ~~~
src/itmmorgue.h:68:34: note: in definition of macro ‘warnf’
   68 |         snprintf(___buf, BUFSIZ, fmt, __VA_ARGS__); \
      |                                  ^~~
src/config.c:256:35: note: format string is defined here
  256 |             warnf("[info] Config: %s: not found.", buf);
      |                                   ^~
In file included from src/config.c:4:
src/itmmorgue.h:68:9: note: ‘snprintf’ output between 28 and 8219 bytes into a destination of size 8192
   68 |         snprintf(___buf, BUFSIZ, fmt, __VA_ARGS__); \
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/config.c:256:13: note: in expansion of macro ‘warnf’
  256 |             warnf("[info] Config: %s: not found.", buf);
      |             ^~~~~
cc1: all warnings being treated as errors
make: *** [Makefile:40: bin/config.o] Error 1

found by kk

[ValeriyKr]

Ветка master, воспроизведено на debian, gcc 8.3.0.

[zhmylove]

@ValeriyKr считаю, достаточно отключить format-truncation warning, т.к. мы намеренно используем snprintf. Согласен?

[ValeriyKr]

@zhmylove блин, я вчитался в код. Это из разряда implicit fallthrough, только ещё бредовее. Предупреждение о том, что функция, используемая по своему назначению может сработать так, как описывается в документации. Согласен, бредовый варнинг.