Auto merge of #121662 - saethlin:precondition-unification, r=RalfJung

Distinguish between library and lang UB in assert_unsafe_precondition

As described in https://github.com/rust-lang/rust/pull/121583#issuecomment-1963168186, `assert_unsafe_precondition` now explicitly distinguishes between language UB (conditions we explicitly optimize on) and library UB (things we document you shouldn't do, and maybe some library internals assume you don't do).

`debug_assert_nounwind` was originally added to avoid the "only at runtime" aspect of `assert_unsafe_precondition`. Since then the difference between the macros has gotten muddied. This totally revamps the situation.

Now _all_ preconditions shall be checked with `assert_unsafe_precondition`. If you have a precondition that's only checkable at runtime, do a `const_eval_select` hack, as done in this PR.

r? RalfJung
This commit is contained in:
bors 2024-03-10 01:23:54 +00:00
commit 45f87a0627

View file

@ -174,7 +174,7 @@ fn check_rvalue<'tcx>(
))
}
},
Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf | NullOp::OffsetOf(_) | NullOp::DebugAssertions, _)
Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf | NullOp::OffsetOf(_) | NullOp::UbCheck(_), _)
| Rvalue::ShallowInitBox(_, _) => Ok(()),
Rvalue::UnaryOp(_, operand) => {
let ty = operand.ty(body, tcx);