Bug 113852

Summary: mess with signbit function in octave source rpm
Product: Red Hat Enterprise Linux 3 Reporter: Sysoltsev Slawa <vyatcheslav.sysoltsev>
Component: octaveAssignee: Lon Hohberger <lhh>
Status: CLOSED RAWHIDE QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: 3.0   
Target Milestone: ---   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: 2.1.57-2 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2004-09-29 21:07:27 UTC Type: ---
Regression: --- Mount Type: ---
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Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description Flags
Include math.h in lo_ieee.h
none
Include math.h and define _GNU_SOURCE to get signbit definition none

Description Sysoltsev Slawa 2004-01-19 15:32:44 UTC 
Description of problem:
There is some mess in octave package with signbit functon. At first, 
EL3.0 have signbit function defined in math.h for __USE_ISOC99 
compilation (by default any C++, but not C), but configure isnât able to 
detect that:

checking for copysign... yes
checking for signbit... no
checking for acosh... yes

The problem is that configure looks for signbit function body, but on 
linux signbit is a macro, that uses internal __signbit function. So 
configure assumes there is no signbit function and so lo_ieee_signbit 
macro in lo-ieee.h becomes hardcoded 0, that is not pretty good.

Now letâs imagine configure would detect signbit properly. Another 
problem with it that gccâs header <cmath> moves definition of signbit to 
the std namespace, after including <cmath>, ::signbit is undefined 
symbol, but std::signbit is a template function. Therefore in C++ 
sources that use <cmath> you must use std::signbit, not signbit. There 
is such error in Cmatrix.cc, dMatrix.cc, pr-output.cc. Probably macro 
lo_ieee_signbit should be changed to use std::signbit on systems with 
gcc3.2 default compiler.


Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
1. Build octave in usual way on Enterprise Linux 3.0 by gcc3.2
2.
3.
  
Actual results:
signbit isn't detected during configure and lo_ieee_signbit is hardcoded 
as 0.
When you'll fix the bug with signbit detection, you get the compile-time 
error about undefined identifier "signbit"

Expected results:
octave with really working lo_ieee_signbit

Additional info:
Comment 1 Lon Hohberger 2004-06-23 16:01:42 UTC 
Created attachment 101360 [details]
Include math.h in lo_ieee.h

This should fix the problem with respect to signbit being defined as 0.  By
including math.h, signbit will be defined and lo_ieee_signbit() will thus be
defined to signbit().
Comment 2 Lon Hohberger 2004-06-23 16:02:12 UTC 
Patch untested.
Comment 3 Lon Hohberger 2004-06-23 17:38:09 UTC 
Patch fails test.
Comment 4 Lon Hohberger 2004-06-24 18:24:36 UTC 
Created attachment 101380 [details]
Include math.h and define _GNU_SOURCE to get signbit definition

This patch causes inclusion of math.h in lo-ieee.h if signbit and
HAVE_SIGNBIT/HAVE_COPYSIGN aren't defined, with _GNU_SOURCE defined so that
signbit gets defined on platforms which support the _GNU_SOURCE macro.

If signbit is not defined, the build stops. (This isn't necessary, nor
desirable, for upstream use, but can be useful to detect this problem in the
future.
Comment 5 Lon Hohberger 2004-06-24 20:16:59 UTC 
Typo.  s/GUN/GNU/g in the patch.