Hi
I'm encountering a weird problem, when I try to use -fno-weak as one
of the compiler options.
The problem which I'm encountering will be clearer from the test-
program below:
$ cat circle.h
// circle.h
class Circle{
int radius;
public:
Circle(int x):radius(x){};
};
$ cat throw.cpp
#include "circle.h"
using namespace std;
void throwException()
{
throw(Circle(10));
}
$ cat main.cpp
#include "circle.h"
#include<iostream>
using namespace std;
void throwException();
int main(int argc)
{
try{
throwException();
}
catch(Circle x)
{
cout<<"caught circle"<<endl;
}
}
When I don't use -fno-weak, program works fine as expected.
$ g++ -c main.cpp; g++ -c throw.cpp;g++ -o test throw.o main.o
$ ./test
caught circle
But when I use -fno-weak, the exception0handling fails:
$ g++ -c -fno-weak main.cpp; g++ -c -fno-weak throw.cpp;g++ -o test
throw.o main.o
$ ./test
terminate called after throwing an instance of 'Circle'
Aborted
The preliminary examination of the problem suggests that the problem
is with the typeinfo data that C++ exception-handling uses.
For case 1:
$ nm -C test |grep typeinfo
08048c3c V typeinfo for Circle
08048c44 V typeinfo name for Circle
For case 2:
$ nm -C test |grep typeinfo
08048c3c r typeinfo for Circle
08048c5c r typeinfo for Circle
08048c44 r typeinfo name for Circle
08048c64 r typeinfo name for Circle
It appears that since two different entries are being maintained for
same type, the try-catch mechanism fails to identify the thrown type.
gcc version being used is 4.2.0; but I've also reproduced this with
gcc version 3.3.3
I surely do need to use -fno-weak.
Also it won't be possible for me to move throwException() to
main.cpp.
Is there any way out here??
Regards
Amit
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