Re: [fortran] Different FUNC_DECLS with the same DECL_NAME - MAIN__ and named PROGRAM main functions [was Re: gcc-4.5-20090528 is now available]

[Dave Korn <dave dot korn dot cygwin at googlemail dot com>]

Tobias Burnus wrote:

  Hi Tobias,

> Hmm, that should not be the case that the middle end gets confused. I
> think there is some merit in printing also the name, e.g., HelloWorld
> rather than MAIN__ in middle end warnings ("unused variable foo in
> HelloWorld"), but otherwise the name given to the program in gimple
> shouldn't matter as long as the assembler name is MAIN__.
> 
> Seemingly there are some issues; however, they do not seem to be new.
> MAIN__ was before generated and the main() was linked from the library.
> The library's main (in fmain.c / libgfortranbegin.a) should already have
> called __main(). Thus if gimple_expand_cfg() automatically adds __main()
> calls for "main" then this must have happened before.
> 
>> I think this is probably an invalid way for the front-end to drive the
>> mid-end - it's ok when the two functions are semantically the same, as when
>> C++ clones constructors, but these are actually two entirely different
>> functions, and in particular, only one of them should cause
>> expand_main_function to be called.  I'd like that to be the real "main"
>> function, which is where the fortran runtime init gets called, rather than
>> "MAIN__", which is the user-level main function, because the runtime init
>> itself might need to use st_printf and that won't work until __main() is
>> called, but I'm not sure how to disetangle the two now.
>>   
> 
> I agree that for "main" the call to "__main()" should happend and thus
> expand_main_function should be called. I'm not sure in about the exact
> assumptions of the middle end. In principle, it would be OK if the
> MAIN__ function would show up as MAIN__ in gimple/-fdump-tree-original.
> The only potential inconvenience I see, is the mentioned reference to
> MAIN__ instead of <program name> in middle-end warnings, which can
> confuse users.

  Wouldn't the simplest thing be to rename the other main function - the
initialisation one that is automatically generated by create_main_function()?
 It could be called anything different we liked, and it's not user-visible, so
it ought to not be a problem to rename?

    cheers,
      DaveK