DOKK / manpages / debian 10 / allegro5-doc / al_destroy_display.3alleg5.en
al_destroy_display(3alleg5) al_destroy_display(3alleg5)

al_destroy_display - Allegro 5 API

#include <allegro5/allegro.h>
void al_destroy_display(ALLEGRO_DISPLAY *display)
    

Destroy a display.

If the target bitmap of the calling thread is tied to the display, then it implies a call to “al_set_target_bitmap(NULL);” before the display is destroyed.

That special case notwithstanding, you should make sure no threads are currently targeting a bitmap which is tied to the display before you destroy it.

al_set_target_bitmap(3alleg5)

Allegro reference manual