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03d03c666c
The current complexities in `assert_unsafe_precondition` are delicately balancing several concerns, among them compile times for the cases where there are no debug assertions. This comes at a large runtime cost when the assertions are enabled, making the debug assertion compiler a lot slower, which is very annoying. To avoid this, we always inline the check when building with debug assertions. Numbers (compiling stage1 library after touching core): - master: 80s - just adding `#[inline(always)]` to the `cfg(bootstrap)` `debug_assertions`: 67s - this: 54s So this seems like a good solution. I think we can still get the same run-time perf improvements for other users too by massaging this code further (see my other PR about adding `#[rustc_no_mir_inline]`) but this is a simpler step that solves the imminent problem of "holy shit my rustc is sooo slow". Funny consequence: This now means compiling the standard library with dbeug assertions makes it faster (than without, when using debug assertions downstream)!