Effects/keyword generics MVP
This adds `feature(effects)`, which adds `const host: bool` to the generics of const functions, const traits and const impls. This will be used to replace the current logic around const traits.
r? `@oli-obk`
Remove chalk support from the compiler
Removes chalk (`-Ztrait-solver=chalk`) from the compiler and prunes any dead code resulting from this, mainly:
* Remove the chalk compatibility layer in `compiler/rustc_traits/src/chalk`
* Remove the chalk flag `-Ztrait-solver=chalk` and its `TraitEngine` implementation
* Remove `TypeWellFormedFromEnv` (and its many `bug!()` match arms)
* Remove the chalk migration mode from compiletest
* Remove the `chalkify` UI tests (do we want to keep any of these, but migrate them to `-Ztrait-solver=next`??)
Fulfills rust-lang/types-team#93.
r? `@jackh726`
Make RPITITs assume/require their parent method's predicates
Removes a FIXME from the `param_env` query where we were manually adding the parent function's predicates to the RPITIT's assumptions.
r? `@spastorino`
Various impl trait in assoc tys cleanups
r? `@compiler-errors`
All commits except for the last are pure refactorings. 274dab5bd658c97886a8987340bf50ae57900c39 allows struct fields to participate in deciding whether a function has an opaque in its signature.
best reviewed commit by commit
Don't ICE on unnormalized struct tail in layout computation
1. We try to compute a `SizeSkeleton` even if a layout error occurs, but we really only need to do this if we get `LayoutError::Unknown`, since that means our type is too polymorphic to actually compute the full layout. If we have other errors, like `LayoutError::NormalizationError` or `LayoutError::Cycle`, then we can't really make any progress, since this represents an actual error.
2. Avoid using `normalize_erasing_regions` and `struct_tail_erasing_lifetimes` since those ICE on normalization errors, and since we may call `layout_of` in HIR typeck, we don't know for certain that we're on the happy path.
Fixes#112736
