what does '-Wall' flag in the clang mean?

Question

I am reading a Makefile of one c file.

clang -ggdb -std=c99 -Wall -Werror -o generate generate.c

I am unable to understand what -Wall flag in the above line means?

Answer 1

-Wall means to enable all compiler warnings. And -Werror means treat all warnings as errors. In other words, any possible warning that the compiler has determined will be shown to you if your code meets it, and it will be treated as a compile error that must be fixed.