https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89608
Bug ID: 89608
Summary: Undetected iterator invalidations on unordered
containers in debug mode
Product: gcc
Version: 8.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: mafrasi2 at gmail dot com
Target Milestone: ---
Created attachment 45906
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=45906&action=edit
Partial fix for unordered_set
Many iterator invalidations on unordered containers are not detected in debug
mode:
```
#include <debug/unordered_set>
#include <iostream>
int main() {
__gnu_debug::unordered_set<int> myset;
myset.insert(0);
myset.insert(1);
for (auto it = myset.begin(), end = myset.end(); it != end; ++it) {
std::cout << *it << "\n";
myset.insert(2);
}
}
```
This example outputs `1` on my system and doesn't report the access to an
invalidated iterator.
The attached patch fixes the example and the same thing can be done to the
other affected containers. The bug can still be triggered with an explicit
rehash, though.
That said, this may very well be intended behavior since I'm not very
knowledgeable of the C++ standard in general, but using the libc++ debug mode,
it is reported as invalidation both in the example and with the explicit
rehash.
