Re: debugging GNAT programs

[dewar@cs.nyu.edu (Robert Dewar)]

"This step could eventually be skipped IMHO"

The step referred to is generating a source program from the binder for
the main program (although I think the writer also was under the
mis-conception that other Ada compilation went through C).

But with regards to the binder, it is *very* important that source code is
generated, because it means you can step through the elaboration code just
as you would debug any other source code using whatever source level
debugger you normally use for the rest of the program. There have been some
Ada systems which precisely skipped this step, and as a consequence 
debugging the elaboration code could be tricky.

We think it is a definite advantage to generate source for the main program,
and have no intention of changing it. As I mentioned before, we do intend
to have the option of generating the main program in Ada (indeed we will
probably make this the deault), but that's for later. We have introduced
attributes that let an Ada program call the elaboration routines for
packages precisely so that the main program can easily be written in Ada.

Apart from the conceptual clarification of having the Ada main program be
in Ada, there is in some environments a real advantage in disk cache usage
in not having to load the C compiler to compile simple Ada programs. This
point was discussed extensively in a thread on CLA some months ago (along
with an extensive philosophical discussion in which others felt that generating
the main program in C somehow declared that C was a superior language to
Ada -- not quite sure I ever managed to follow that logic, but anyway we
do intend to "fix" this "problem".

Note that we will still leave the option to generate a main program in C, 
because in some mixed language environments this has advantages.