prepare (1/3): 
finished

make (2/3): 
gcc -g -o l6 ex3.c -O2 -Wall -Wextra -Werror -Wno-unused-result -Wconversion -Wvla
ex3.c: In function 'read_and_sort':
ex3.c:197:9: error: 'tmp_data' may be used uninitialized in this function [-Werror=maybe-uninitialized]
         insert_lst(lst, key_ins, tmp_data);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
Makefile:4: recipe for target 'l6' failed
make: *** [l6] Error 1

build failed