/in/foo.c: In function 'main':
/in/foo.c:9:22: warning: statement with no effect [-Wunused-value]
   for (i = 1; i++; i <= n)
                    ~~^~~~
/in/foo.c:9:16: warning: iteration 2147483646 invokes undefined behavior [-Waggressive-loop-optimizations]
   for (i = 1; i++; i <= n)
               ~^~
/in/foo.c:9:3: note: within this loop
   for (i = 1; i++; i <= n)
   ^~~