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* [Bug c++/11518] New: (b==a && c==a && c!=b) == true
@ 2003-07-14 12:36 gsinai at yudit dot org
2003-07-14 12:45 ` [Bug c++/11518] " pinskia at physics dot uc dot edu
0 siblings, 1 reply; 2+ messages in thread
From: gsinai at yudit dot org @ 2003-07-14 12:36 UTC (permalink / raw)
To: gcc-bugs
PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11518
Summary: (b==a && c==a && c!=b) == true
Product: gcc
Version: 2.96 (redhat)
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: gsinai at yudit dot org
CC: gcc-bugs at gcc dot gnu dot org,gsinai at yudit dot org
(b==a && c==a && c!=b)
Tths equation is somtimes true with redhat built gcc 2.6 on Pentiums.
a: double type
b: function call returning a double
c: method call returning a double
/*!
* \file double.cpp
* \brief If a==b and b==c then c==b? Not always. Not everywhere.
* \author Gaspar Sinai <gsinai@yudit.org>
* \date 2003-07-13.
* Results:
*--------------------------------------------------------------
* Surprises
*--------------------------------------------------------------
* Pentium g++ 2.96:
* setting: a_double: 0.1
* setting: get_double(): 0.1
* setting: a_Double.get(): 0.1
* comparing: a_double == get_double()
* comparing: a_double == a_Double.get()
* comparing: a_Double.get() != get_double()
*--------------------------------------------------------------
* Pentium g++ 3.2.1:
* setting: a_double: 0.1
* setting: get_double(): 0.1
* setting: a_Double.get(): 0.1
* comparing: a_double != get_double()
* comparing: a_double == a_Double.get()
* comparing: a_Double.get() != get_double()
*--------------------------------------------------------------
* Expected
*--------------------------------------------------------------
* Alpha g++ 2.96:
* setting: a_double: 0.1
* setting: get_double(): 0.1
* setting: a_Double.get(): 0.1
* comparing: a_double == get_double()
* comparing: a_double == a_Double.get()
* comparing: a_Double.get() == get_double()
*--------------------------------------------------------------
* The interesting function:
* static double
* get_double(void)
* {
* int i=1;
* // If you change i to 1 it will work everywhere.
* return (double (i) / 10.0);
* }
*/
#include <iostream>
static double get_double(void);
class Double
{
public:
double get(void);
void set(double d);
protected:
double m_d;
};
double
Double::get (void)
{
return m_d;
}
void
Double::set (double d)
{
m_d = d;
}
static double
get_double(void)
{
int i=1;
// If you change i to 1 it will work everywhere.
return (double (i) / 10.0);
}
int
main()
{
double a_double = get_double();
Double a_Double;
a_Double.set (get_double());
std::cout << "setting: a_double: " << a_double << std::endl;
std::cout << "setting: get_double(): " << get_double() << std::endl;
std::cout << "setting: a_Double.get(): " << a_Double.get() << std::endl;
if (a_double == get_double())
{
std::cout << "comparing: a_double == get_double()" << std::endl;
}
if (a_double != get_double())
{
std::cout << "comparing: a_double != get_double()" << std::endl;
}
if (a_double == a_Double.get())
{
std::cout << "comparing: a_double == a_Double.get()" << std::endl;
}
if (a_double != a_Double.get())
{
std::cout << "comparing: a_double != a_Double.get()" << std::endl;
}
if (a_Double.get() == get_double())
{
std::cout << "comparing: a_Double.get() == get_double()" << std::endl;
}
if (a_Double.get() != get_double())
{
std::cout << "comparing: a_Double.get() != get_double()" << std::endl;
}
return (0);
}
^ permalink raw reply [flat|nested] 2+ messages in thread
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2003-07-14 12:36 [Bug c++/11518] New: (b==a && c==a && c!=b) == true gsinai at yudit dot org
2003-07-14 12:45 ` [Bug c++/11518] " pinskia at physics dot uc dot edu
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