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libstdc++/9396: ambiguities with abs()
- From: snyder at fnal dot gov
- To: gcc-gnats at gcc dot gnu dot org
- Date: Tue, 21 Jan 2003 22:55:18 CST
- Subject: libstdc++/9396: ambiguities with abs()
- Reply-to: snyder at fnal dot gov
>Number: 9396
>Category: libstdc++
>Synopsis: ambiguities with abs()
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: unassigned
>State: open
>Class: rejects-legal
>Submitter-Id: net
>Arrival-Date: Wed Jan 22 04:56:00 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator: scott snyder
>Release: 3.4 20030121 (experimental)
>Organization:
<organization of PR author (multiple lines)>
>Environment:
System: Linux karma 2.4.19-emp_2419p5a829i #1 Tue Sep 3 17:42:17 EST 2002 i686 unknown
Architecture: i686
<machine, os, target, libraries (multiple lines)>
host: i686-pc-linux-gnu
build: i686-pc-linux-gnu
target: i686-pc-linux-gnu
configured with: ../gcc/configure --prefix=/usr/local/gcc --enable-threads=posix --enable-long-long
>Description:
When compiling the source below, g++ 3.4 gives the errors:
$ g++ -c x.cc
x.cc: In function `double foo(double)':
x.cc:8: error: call of overloaded `abs(double&)' is ambiguous
/usr/include/stdlib.h:699: error: candidates are: int abs(int)
/usr/local/gcc/include/c++/3.4/cstdlib:142: error: long long
int __gnu_cxx::abs(long long int)
$
The error goes away if i reverse the order of the two includes
(putting cstdlib before cmath) or if i explicitly qualify the abs()
call with std::.
This source compiles without error with g++ 3.1.
>How-To-Repeat:
---------------------------
#include <cmath>
#include <cstdlib>
using std::abs;
double foo (double x)
{
return abs (x);
}
---------------------------
>Fix:
<how to correct or work around the problem, if known (multiple lines)>
>Release-Note:
>Audit-Trail:
>Unformatted: