Upgrade toolchain to nightly-2024-04-15

[celinval]

Related changes:

• Add Ord::cmp for primitives as a BinOp in MIR rust-lang/rust#118310:
  Add Ord::cmp for primitives as a BinOp in MIR
• Implement minimal, internal-only pattern types in the type system rust-lang/rust#120131:
  Add support to Pat pattern type
• rename ptr::from_exposed_addr -> ptr::with_exposed_provenance rust-lang/rust#122935:
  Rename CastKind::PointerWithExposedProvenance
• Try using a dyn Debug trait object instead of a closure rust-lang/rust#123097:
  Adapt to changes to local_def_path_hash_to_def_id

Resolves #3130, #3142

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 and MIT licenses.

[celinval]

Note to self: Add a test to Pat to ensure we capture invalid valid generated during a transmute.

[tautschnig]

For my own learning: the changes in 1abfa0f ("Fix BinOp implementation") seem much bigger than what I initially had for the Cmp operator. Could you please explain a bit?

[celinval]

For my own learning: the changes in 1abfa0f ("Fix BinOp implementation") seem much bigger than what I initially had for the Cmp operator. Could you please explain a bit?

I added a comment to the code, which explains why this is slightly more complex. The result of a comparison is not an integer, but an enumeration. So Kani would crash with the previous implementation when it would try to assign the comparison expression due to mismatched type.

Part of the logic I added is to guarantee that the transmute is safe, but it is not really necessary. But I check that the enumeration layout matches what we expect, which is an i8 that goes from -1 to 1.

[celinval]

I'm merging this PR despite the issue with the benchmark job, since it is blocked due to a bug in the benchcomp tool itself. It is failing to generate the comparison tables since the base commit is currently broken due to #3138