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Date: Fri, 9 Jan 2009 08:57:26 -0700
From: John Hein <jhein@timing.com>
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Cc: freebsd-standards@FreeBSD.ORG, das@FreeBSD.ORG,
	freebsd-gnats-submit@FreeBSD.ORG, imp@FreeBSD.ORG
Subject: Re: standards/130067: Wrong numeric limits in system headers?
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V=E1clav Haisman wrote at 22:56 +0100 on Jan  8, 2009:
 > David Schultz wrote, On 6.1.2009 20:03:
 > > On FreeBSD/i386, long doubles are represented with 64 bits of
 > > precision, but computations are performed with 53 bits of
 > > precision. In a sane world, this discrepancy wouldn't exist, but
 > > for reasons I won't get into, they do, and probably always will.
 > > =

 > > C99 defines the LDBL constants based on what can be represented,
 > > not what can be computed as the result of arithmetic operations,
 > > so my interpretation is that the values in float.h are correct,
 > > though confusing.
 > I am not language lawyer but even if it were true that the constants a=
re
 > right, there is still the problem that they (especially the LDBL_MAX v=
alue)
 > are useless with the provided GCC. Either GCC or the headers should be=

 > changed. Otherwise the constants are rather useless and unusable.

FWIW, when you compile the OP's sample code on i386 with -pedantic
(with 6.x's base gcc 3.4.6 or 7.x's base gcc 4.2.1), you get:

x.cc:11: error: floating constant exceeds range of 'long double'

(the LDBL_MAX line)

That seems to tip the scale more to the 'float.h is wrong' side.