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From: "Johnny Willemsen" <jwillemsen AT remedy DOT nl>
To: <cygwin AT cygwin DOT com>
Subject: RE: log2 as function not as macro
Date: Tue, 15 Jun 2004 19:53:46 +0200
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Hi,

>   And the answer there will probably be that if your code depends on
whether
> this function is a macro or a real function then your code is not valid C.
> The C language spec specifically says that implementations are free to
> provide library functions as macros as well as functions.  See
>
> http://www.opengroup.org/onlinepubs/009695399/basedefs/math.h.html
>
> and in particular the lines that say "The following shall be declared as
> functions and may also be defined as macros. Function prototypes shall be
> provided."
>
>   So if your code has a problem with that, your code does not comply with
> the C language spec.
>
>     cheers,
>       DaveK

Dave,

To be fair, the original poster described the exact problem:
> log2 as macro is hard to use in projects that also define a log2 function.
I'm not sure how your link can be reconciled with this, but at a guess,
projects that define a log2() function are expected to follow "#include
<math.h>" with "#undef log2".

Yes, you are correct, we do this now in this way. Cygwin is the only
environment for which we have to do this and I just don't like it. It means
we have to include math.h in a header file where we don't need it. A change
to a function would make life easier.

Johnny


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