[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: new module 'isnan-nolibm'

From: Eric Blake
Subject: Re: new module 'isnan-nolibm'
Date: Sat, 24 Feb 2007 19:42:10 -0700
User-agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv: Gecko/20061207 Thunderbird/ Mnenhy/

Hash: SHA1

According to Bruno Haible on 2/24/2007 7:08 PM:
> Cygwin:      isnan() is a function, defined in cygwin.dll

No, on cygwin, isnan is a macro in <math.h> that wraps the internal
functions __isnan{,lf}, and the isnan entry point in cygwin1.dll exists
only for backwards compatibility for multi-year-old apps that were
compiled against cygwin prior to the POSIX compliance bug being fixed of
providing isnan only as a macro.  And you still didn't catch my point that
on cygwin, you don't need -lm to get isnan() to work, whether or not it is
an exported function, since modern code should not be linking against the
entry point isnan on cygwin anyways.  Checking AC_CHECK_FUNC([isnan]) is
wrong since POSIX does not guarantee that isnan is a function; instead,
you must check whether including <math.h> and using isnan() will link
correctly in the absence of -lm.

- --
Don't work too hard, make some time for fun as well!

Eric Blake             address@hidden
Version: GnuPG v1.4.5 (Cygwin)
Comment: Public key at home.comcast.net/~ericblake/eblake.gpg
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org


reply via email to

[Prev in Thread] Current Thread [Next in Thread]