As described in the previous section, by default gnatbind checks that object files are consistent with one another and are consistent with any source files it can locate. The following switches to control access to sources.
Require source files to be present. In this mode, the binder insists on being able to locate all source files that are referenced and checks their consistency. In normal mode, if a source file cannot be located it is simply ignored. If you specify this switch, a missing source file is an error.
Exclude source files. In this mode, the binder only checks that ALI files are consistent with one another. Source files are not accessed. The binder runs faster in this mode, and there is still a guarantee that the resulting program is self-consistent. If a source file has been edited because it was last compiled and you specify the this switch, the binder will not detect that the object file is out of date with the source file. Note that this is the mode that is automatically used by gnatmake because in this case the checking against sources has already been performed by gnatmake.