https://issues.dlang.org/show_bug.cgi?id=21940
--- Comment #3 from Dlang Bot <dlang-bot@dlang.rocks> --- dlang/dmd pull request #12600 "merge stable" was merged into master: - fea011ecb74ca6f9a9124980e3ec0c9c60a5f7e3 by MoonlightSentinel: Fix 21940 - Recognize on/off as valid options for -check Check for the special values `"on"` and `"off"` before parsing `<option>=<state>`. https://github.com/dlang/dmd/pull/12600 --