Thread: warning: assignment from incompatible pointer type - drawing_area

Hi folks,

In function main() I do the following declaration:

Code:

  
GtkWidget *drawing_area;

drawing_area = gtk_builder_get_object (builder, "draw_area");

where builder was created from a .ui file and "draw_area" is the ID of my drawing area in the .ui file.

When I compile the code, even though the program appears to run successfully, the gcc compiler shouts at me:

warning: assignment from incompatible pointer type [-Wincompatible-pointer-types]
drawing_area = gtk_builder_get_object (builder, "draw_area");
^

Why is this happening? I have other GObjects declared in a similar way and the compiler doesn't complain about them.

The compiler doesn't know that GtkWidget* and GObject* are compatible (i.e., it doesn't know that GtkWidget "is-a" GObject). You need to either make drawing_area a GObject* or cast the return value of gtk_builder_get_object to a GtkWidget*.