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Date: Thu, 15 Nov 2007 18:23:00 -0000
Subject: [Bug fortran/34112]  New: Add $!DEC ATTRIBUTE support for 32bit Windows' STDCALL
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From: "burnus at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
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32bit Windows uses a different calling convention (called procedure pops the
stack, not caller) with a symbol name _<name>@n, where n is the number of bytes
to pop off.

See also:
http://groups.google.com/group/comp.lang.fortran/browse_thread/thread/19d77dfc75f8be58
http://gcc.gnu.org/ml/fortran/2007-11/msg00074.html

As the standard makes not provisions and !DEC$ (*DEC$, cDEC$) is widely used,
gfortran should accept the following:

  function CallWndRetProc(nCode, wParam, lParam)
  !DEC$ ATTRIBUTES STDCALL,DECORATE, ALIAS: 'CallWndRetProc' :: CallWndRetProc 
  end function

Documentation:
http://www.intel.com/software/products/compilers/docs/fmac/doc_files/source/extfile/lref_for/source_files/rfattcst.htm
http://www.intel.com/software/products/compilers/docs/fmac/doc_files/source/extfile/lref_for/source_files/rfattrib.htm

They seem to map to
(http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html):

STDCALL  ->  __attribute__(stdcall)
ALIAS    ->  __attribute__(alias("name"))
DECORATE -> ?

The problem with decorate is that its meaning depends on the platform. It may
decorate the "name" of alias with a "_" prefix and "@n" postfix or only with a
"_" prefix. Maybe one should start with STDCALL and ALIAS.

For alias one should do something as in c-pragma.c's apply_pragma_weak:

decl_attributes (&decl, build_tree_list (get_identifier ("alias"),
                                         build_tree_list (NULL, value)),
                 0);


-- 
           Summary: Add $!DEC ATTRIBUTE support for 32bit Windows' STDCALL
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: burnus at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34112