[Fortran,Patch] PR40955 - Save ext_attr such as STDCALL to .MOD file

[Tobias Burnus]

On Tue, Aug 04, 2009 at 10:23:19AM +0200, Tobias Burnus wrote:
> Another STDCALL (and friends) omission: The extended attribute was not
> saved in the MOD file.

Attached patch supercedes that patch. New features:
- gfc_copy_attr now also copies the extended attributes
- Extended attributes now also work with procedure (pointers), inheriting
  the attributes from the (abstract) interface (or-ed together with local
addition; if a combination does not make sense, I leave it to the middle
end to warn)

And I changed gfc_add_ext_attr to take an enum as argument instead of
an unsigned int. The reason is that I was tempted to use
  gfc_add_ext_attr (sym, attr->ext_attr)
which does not work. (In gfc_add_ext_attr the argument a "1" is bit
shifted depending on the argument.) With enum there is at least the
chance that we get a compile-time warning (or via -Werror an error).

> I could have bumped the MOD file version; however, as it already was
> bumped for 4.5 and as the message is somewhat clear
> ("Fatal Error: Reading module ... Expected attribute bit name" ...
> and "... Expected integer"), I have not done it.
> 
> I have bootstrapped and regtested (check gfortran & libgomp) it on
> x86-64-linux, but I cannot really test it - except that for a simple
> test case, there is now an additional
>  test.f90:10:0: warning: 'stdcall' attribute ignored
> for the CALL, i.e. it seems to work correctly.

The procedure part was tested on x86-64-linux with the test case from
the PR. (GCC on x86-64 shows nice warnings that the options was ignored.)

> I do not know how to best create a test case, thus I have not added
> one. I think we badly need a test case for 32bit MinGW/Cygwin, which
> calls some STDCALL Windows ABI function.

Another option is to add a test for x86-64 and check for dg-warning.
I can add such a patch, if it is deemed to be useful.

> OK for the trunk?

Tobias
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