Some compilers do. Some compilers do not tell you a thing "'cause you should use lint". Get used to the former and if you happen to come across the other you end up wasting hours of time. Luckily it did not take me so long when I was asked to make some changes while doing the "Unix and C I." exam several years ago after only ever using Borland C for a bit. The fact that there was just a single plain old textmode terminal with vi or pico to do anything with did not help a bit.