foo.c: In function ‘main’:
foo.c:21:9: warning: ‘signal’ may be used uninitialized [-Wmaybe-uninitialized]
   21 |         printf("%d\n",signal);
      |         ^~~~~~~~~~~~~~~~~~~~~
foo.c:11:21: note: ‘signal’ was declared here
   11 |                 int signal;
      |                     ^~~~~~