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Date: Wed, 31 Dec 2003 10:05:31 -0500
From: Hyman Rosen <hyrosen@mail.com>
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Subject: Re: GNAT parameter passing, C-style?
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Date: 2003-12-31T10:05:31-05:00
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Frank J. Lhota wrote:
> For that reason, C compilers have to assume the C calling convention,
 > unless the user indicates via declaration or command line options.

No, this is false. The C Standard essentially says that when you call a
function without a prototype, the compiler constructs one for you based
on the parameters you are supplying in the call. If this constructed
prototype is not compatible with the definition of the function, then the
program has undefined behavior.

(This is jokingly referred to as the Miranda rule: You are entitled to a
prototype. If you do not supply one, one will be provided for you.)

Functions with variable argument lists must be prototyped before they are
called, or again the results are undefined.

The upshot is that even when calling a function without a prototype, the
compiler may pass arguments any way it likes, and it is absolutely not
required to "push" them onto a "stack" in any particular order.