| 12 Feb 2026 |
 ris_ | i should probably undo at least the extensive one | 22:44:08 |
| ris_ | though it's weird 26.xx shipping without flags 25.11 had enabled | 22:44:37 |
| ris_ | i'm sure some packages must be seeing a performance impact | 22:44:54 |
|  Adam joined the room. | 23:15:38 |
| 13 Feb 2026 |
 emily | are there numbers for the expected impact of the two? | 03:27:02 |
| emily |
Extensive mode, which contains all the checks from fast mode and some additional checks for undefined behavior that incur relatively little overhead but aren’t security-critical. Production builds requiring a broader set of checks than fast mode should consider enabling extensive mode. The additional rigour impacts performance more than fast mode: we recommend benchmarking to determine if that is acceptable for your program.
| 03:27:29 |
| emily | doesn't sound like it should be too bad | 03:27:33 |
| emily | specifically marked as suitable for production at least | 03:27:56 |
| emily | fwiw the main user of libc++ in Nixpkgs is macOS and _LIBCPP_HARDENING_MODE_DEFAULT is already 2 (fast) on that platform | 03:29:42 |
| emily | so libcxxhardeningfast is just a nop | 03:30:04 |
|  hoplopf joined the room. | 10:25:27 |
