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From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c
Subject: Re: va_start without the first argument?
Date: Tue, 14 Mar 2017 09:18:13 -0700
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David Brown <david.brown@hesbynett.no> writes:
[...]
> #ifdef __GNUC__
> #define IS_COMPILE_TIME_CONSTANT(x) __builtin_constant_p(x)

I'd parenthesize this:

#define IS_COMPILE_TIME_CONSTANT(x) (__builtin_constant_p(x))

I'm not sure whether it can make a difference, but it's easier to add
the parentheses than to prove that they're not needed.

> #else
> #define IS_COMPILE_TIME_CONSTANT(x) (0)

I wouldn't bother with the parentheses here; there are no precedence
issues with a single constant.

> #endif

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"