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[Caml-list] Question about warning message.
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Date: 2004-05-05 (16:41)
From: Roberto Bagnara <bagnara@c...>
Subject: Re: [Caml-list] Question about warning message.
David Brown wrote:
> On Wed, May 05, 2004 at 05:16:06PM +0200, Claudio Trento wrote:
>>my g++ compiler show me this warning:
>>    << warning: unused variable `int caml__dummy_n' >>
> It is part of the construct the headers use to implement the
> CAMLparam... macros.  Strictly it isn't necessary in C++, since you can
> have declarations in the middle of a block, but then there would be
> different constructs for C and C++.

That would not be a problem: most header files that must work
with both C and C++ do that.  For example, one thing that
the OCaml include files out to start and end with is

#ifdef __cplusplus
extern "C" {


#ifdef __cplusplus
} /* extern "C" */

Similar things based on the __cplusplus macro allows to obtain
header files that are 100% standard compliant with respect to
both C and C++.

> BTW, what about having a
>   (void) caml__dummy_##x;
> at the end of the CAMLxparam... macros?  This does shut up the warning,
> at least on gcc.

This would do the trick, even though it is a bit of a hack.
What do the OCaml developers think?
Are they willing to accept patches to solve these problems?


Prof. Roberto Bagnara
Computer Science Group
Department of Mathematics, University of Parma, Italy

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