File Format Compatibility between different compilers

[casado@enstb.enst-bretagne.fr (casado)]

Imagine this scenario on one computer:

There are two different Ada compilers, C_A and C_B;
There is a source program to create a direct file F, P_C.
There is a source program to read a direct file F, P_R.

P_C is compiled by C_A to obtain a object program P_C_A.
P_C is compiled by C_B to obtain a object program P_C_B.

P_R is compiled by C_A to obtain a object program P_R_A.
P_R is compiled by C_B to obtain a object program P_R_B.

P_C_A is executed to produce the file F_A.
P_C_B is executed to produce the file F_B.

F_A is read by P_R_A and no problem is detected. This is normal.
F_B is read by P_R_B and no problem is detected. This is normal.

F_A is read by P_R_B and  problems are detected. Is this  normal?
F_B is read by P_R_A and  problems are detected. Is this  normal?

The problems detected were to read meaningless data when the file
has been created by a program that was compiled by a different compiler.

Has anybody tried this scenario?

I did it when I compiled a Pretty_printer that one friend had modified.

The compiler utilized by my friend and the one I utilized come from
different manufacturer.

He created several parameters files for his Pretty_Printer.

My Pretty_printer read these files, but the data contained in them were
meaningless so my Pretty_printed aborted the execution.I had to create
these files with the programs compiled by my compiler.

Later, I searched in the LRM, and in <14.1:7> you can read:

The language does not define what happens to external files after the
completion of the main program (in particular, if corresponding files
have not been closed). The effect of input_output for access types is
					   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
implementation-depended.
^^^^^^^^^^^^^^^^^^^^^^^

I have concluded that this kind of subtleties must be normalized if we
want to mix tools coming from different manufactures. I do not want to
imagine how many time the people is wasting on this kind of problems.

Do you think that this must be normalized?

Luis M. Casado

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