[gcc/Linux] std::numeric_limits<int>::traps = false when integer arithmetic traps

• Key: STDCXX-624
• Type: Bug
• Status: Closed
• Resolution: Fixed
• Priority: Trivial
• Assignee: Martin Sebor
• Reporter: Martin Sebor
• Component/s: 18. Language Support
• Affects Version/s: 4.2.0
• Fix Version/s: 4.2.1

Description

As an extension, stdcxx defines the value of std::numeric_limits<T>::traps for integer T to be true when there exists an arithmetic operation on type T that traps for some value of T. Based on this definition the program below should always run successfully to completion but when compiled with gcc 4.1.0 with optimization enabled on SUSE Linux Enterprise Server 10 (x86_64) it aborts at runtime. (This is also why the example program limits.cpp produces a DIFF result in some builds).

$ cat t.cpp && make t && ./t
#include <cassert>
#include <cstdio>
#include <cstdlib>
#include <limits>

char digits[] = " +0.?23456789e+01";

int main ()
{
    digits [4] = '0';
    const int zero = (int)std::strtod (digits, 0);

    digits [4] = '1';
    const int x = (int)std::strtod (digits, 0);

    if (!std::numeric_limits<int>::traps) {
        const int div = x / zero;
        const int mod = x % zero;

        std::printf ("%d, %d\n", div, mod);
    }
}
gcc -c -I/amd/devco/sebor/stdcxx-4.2.x/include/ansi   -pthread -I/amd/devco/sebor/stdcxx-4.2.x/include -I/build/sebor/stdcxx-4.2.x-gcc-4.1.0-12D/include -I/amd/devco/sebor/stdcxx-4.2.x/examples/include  -pedantic -nostdinc++ -O2   -W -Wall -Wcast-qual -Winline -Wshadow -Wwrite-strings -Wno-long-long -Wcast-align   t.cpp
gcc t.o -o t -pthread  -L/build/sebor/stdcxx-4.2.x-gcc-4.1.0-12D/lib  -Wl,-R/build/sebor/stdcxx-4.2.x-gcc-4.1.0-12D/lib -lstd12D -lsupc++ -lm 
Floating point exception