flycheck doesn't check

Question

i installed and enabled flycheck but it doesn't find errors in my software (c code), errors that i deliberately inserted to test it

instead it works on a new minimal c file (also not saved)

what could be the problem? thanks in advance

emacs version

GNU Emacs 24.5.1 (x86_64-pc-linux-gnu, GTK+ Version 3.18.6) of 2015-12-14 on binet, modified by Debian

flycheck version

Flycheck version: 0.26snapshot (package: 20151212.411)

flycheck-verify-setup

Syntax checkers for buffer formelement.c in c-mode:

c/c++-clang - predicate: nil - executable: Not found

c/c++-gcc - predicate: t - executable: Found at /usr/bin/gcc

c/c++-cppcheck - predicate: nil - executable: Not found

Flycheck Mode is enabled.

Answer 1

it needs to add each include path to flycheck-gcc-include-path (in my case glib cflags taken from pkg-config)

otherwise flycheck says nothing (no error)