https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113159
Bug ID: 113159
Summary: More robust std::sort for silly comparator functions
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: jengelh at inai dot de
Target Milestone: ---
Type: enhancement
Version: 13.2.1 20231130 [revision 741743c028dc00f27b9c8b1d5211c1f602f2fddd]
(SUSE Linux) x86_64
Input:
#include <algorithm>
#include <cstdlib>
#include <vector>
int main()
{
std::vector<int> v(256);
sort(v.begin(), v.end(), [](int a, int b) -> bool { return rand() & 1;
});
// alternatively, { return true; }
//
// -D_GLIBCXX_DEBUG can diagnose obviously-broken cases like
// {return true;}, but won't necessarily for
// rand()&1 at all times.
}
Observed output:
<SIGSEGV>
Expected output:
Though I recognize this is undefined behavior, I would love to see the
implementation not run into an out-of-bounds access. glibc's qsort for example
stays within the array bounds even if given a buggy comparator like that.
