al_build_shader - Allegro 5 API

       This  is  required  before the shader can be used with al_use_shader(3alleg5).  It should be called after
       successfully  attaching  the  pixel  and/or  vertex  shaders  with  al_attach_shader_source(3alleg5)   or
       al_attach_shader_source_file(3alleg5).

       Returns true on success and false on error, in which case the error log is updated.  The error log can be
       retrieved with al_get_shader_log(3alleg5).

              Note:  If you are using the ALLEGRO_PROGRAMMABLE_PIPELINE flag, then you must specify both a pixel
              and a vertex shader sources for anything to be rendered.

       al_build_shader - Allegro 5 API

al_use_shader(3alleg5), al_get_shader_log(3alleg5)

Allegro reference manual                                                                al_build_shader(3alleg5)

       5.1.6

              #include <allegro5/allegro.h>

              bool al_build_shader(ALLEGRO_SHADER *shader)