Firefox Nightly builds on Arch Linux have started failing with the same error. The regressor is probably bug 1986593. `TemplateLib.h` (probably included through `mozalloc.h`) used to include `<type_traits>` for the use in `nsCycleCollectionNoteChild.h` but that is now missing.
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Firefox Nightly builds on Arch Linux have started failing with the same error. The regressor is probably bug 1986593. `TemplateLib.h` (included through `nsCycleCollectionTraversalCallback.h` → `nscore.h` → `mozalloc.h`) used to include `<type_traits>` for the use in `nsCycleCollectionNoteChild.h` but that is now missing.