Re: [RFC-3] Handle GPC specific name for main function

[Waldek Hebisch <hebisch@math.uni.wroc.pl>]

Pierre Muller wrote:
>   As stated in my other email,
> the whole purpose of this patch is not to
> determine if the source was compiled by GPC, 
> but to get the command 'start' to end up at the right
> location.
>   This right location is either '_p_M0_main_program' or
> 'pascal_main_program'
> (or 'program_Foo' for very old version, that my patch will not support.)
> 

Assuming that the main program is compiled by GPC looking for
'_p_M0_main_program' or 'pascal_main_program' should work fine.
However, if the main program was compiled by some other compiler
the program in principle may still contain such magic symbol
-- using it as start location would be wrong.

In the 'demos' subdirectory of gpc tarball one can find files
'gpc_c_pas.pas', 'gpc_c_unit.pas' and 'gpc_c_c.c' -- this
is a demo program showing how to make main program in C but use
from it Pascal routines.  In this example '_p_M0_main_program' is
never called and the right location for 'start' command is
C main.  It is easy to create mixed mode program without
fake '_p_M0_main_program', but unfortunately the demo creates
fake '_p_M0_main_program'.

Another possibility is program in other language (or compiled
by some other Pascal compiler) which happens to contain
'pascal_main_program'.  I hope that '_p_M0_main_program' is
very unlikely to appear in non-GPC program, but 'pascal_main_program'
is a reasonable name so it makes sense to look for confirmation
that the program is GPC compiled.

'_p_initialize' indicates presence of GPC runtime (so it really
does not help in case of mixed mode programs).  I should also
mention that there was a report that 'libplot' library also
contains '_p_initialize' function...

I also mentioned shared libraries.  Now I think that they pose
no extra problem -- presumably 'start' command will go to
a symbol in main executable and just ignore shared libraries.

-- 
                              Waldek Hebisch
hebisch@math.uni.wroc.pl