https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115399
Bug ID: 115399
Summary: std::tr2::dynamic_bitset shift behaves differently
from std::bitset
Product: gcc
Version: 14.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: adamant.pwn at gmail dot com
Target Milestone: ---
Target: x86-64 Linux
Build: 20240522
Posting a bug on behalf of someone who didn't manage to create an account at
GCC bugzilla due to automatic registration being disabled...
The bug is due to the line
https://github.com/gcc-mirror/gcc/blob/master/libstdc%2B%2B-v3/include/tr2/dynamic_bitset.tcc#L63
being commented out in dynamic_bitset implementation (unlike std::bitset, where
it is present). Uncommenting it should fix the problem.
A simple example program to highlight the discrepancy:
#include <iostream>
#include <bitset>
#include <tr2/dynamic_bitset>
int main() {
std::tr2::dynamic_bitset<> test(91);
test[50] = true;
std::cout << test << "\n";
std::cout << (test << 78) << "\n";
std::cout << "\n";
std::bitset<91> test2;
test2[50] = true;
std::cout << test2 << "\n";
std::cout << (test2 << 78) << "\n";
}
Output:
0000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000
0000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000
0000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000
0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
