On Sat, 28 Aug 2010, Joost van der Sluis wrote:
Hi all,
The safecall calling convention is now implemented for i386/linux in
fpc-trunk. The next step to get XPCom working now is to update the
QueryInterface (and AddRef and ReleaseRef) definitions in IInterface.
Problem is that they are defined as 'stdcall' but to make them work on
Linux/i386 that should be 'cdecl'. So that will change in the near
future. (using an ifdef, so it's stdcall on windows, cdecl on all
others)
This will break backwards compatibility on non-windows systems for users
who implement their own QueryInterface, AddRef and ReleaseRef methods!
But it's easy fixable and the compiler will complain.
The problem that then still remains is that the IID parameter of
QueryInterface has to be passed by reference. Now it's defined as
'const' so it won't be passed by reference in Linux (cdecl).
What does stdcall calling convention currently do on non-windows platforms ?
Because if it is something we decided, it simply means that we should change
it's meaning to be identical to mwpascal: cdecl calling convention, and const
structs passed by reference. If I'm right, 'stdcall' currently
has no meaning on non-windows platforms other than the one we put on it.
It solves all your problems in one go, plus it makes writing header
translations a lot easier. (Pending the question of what the C compiler does
with const structured C parameters)
If that is not possible, then I think Marco's idea of a switch is best.
I see it as similar to the {$packrecords } directive: it doesn't change the
syntax or meaning (as Jonas fears), but does instruct the compiler how to
handle things on a more low-level (in casu: assembler) scale.
I think that having to write
{$ifdef windows}const{$else}constref{$endif} myarg: mytype
for possibly thousands of arguments in an interface description is simply not
an option.
Michael.
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