al_get_shader_log - Allegro 5 API

       Return  a  read-only  string  containing the information log for a shader program.  The log is updated by
       certain functions, such as al_attach_shader_source(3alleg5) or al_build_shader(3alleg5) when there is  an
       error.

       This function never returns NULL.

       al_get_shader_log - Allegro 5 API

al_attach_shader_source(3alleg5), al_attach_shader_source_file(3alleg5), al_build_shader(3alleg5)

Allegro reference manual                                                              al_get_shader_log(3alleg5)

       5.1.0

              #include <allegro5/allegro.h>

              const char *al_get_shader_log(ALLEGRO_SHADER *shader)