Pass each obligation to an fn callback with its respective inference context. This avoids needing to keep around copies of obligations or inference contexts.
Specify usability of inspect_typeck in comment.
use LocalDefId instead of HirId in trait resolution to simplify
the obligation clause resolution
Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Make cycle errors recoverable
In particular, this allows rustdoc to recover from cycle errors when normalizing associated types for documentation.
In the past, ```@jackh726``` has said we need to be careful about overflow errors: https://github.com/rust-lang/rust/pull/91430#issuecomment-983997013
> Off the top of my head, we definitely should be careful about treating overflow errors the same as
"not implemented for some reason" errors. Otherwise, you could end up with behavior that is
different depending on recursion depth. But, that might be context-dependent.
But cycle errors should be safe to unconditionally report; they don't depend on the recursion depth, they will always be an error whenever they're encountered.
Helps with https://github.com/rust-lang/rust/issues/81091.
r? ```@lcnr``` cc ```@matthewjasper```
In particular, this allows rustdoc to recover from cycle errors when normalizing associated types for documentation.
In the past, `@jackh726` has said we need to be careful about overflow errors:
> Off the top of my head, we definitely should be careful about treating overflow errors the same as
"not implemented for some reason" errors. Otherwise, you could end up with behavior that is
different depending on recursion depth. But, that might be context-dependent.
But cycle errors should be safe to unconditionally report; they don't depend on the recursion depth, they will always be an error whenever they're encountered.
Specifically, rename the `Const` struct as `ConstS` and re-introduce `Const` as
this:
```
pub struct Const<'tcx>(&'tcx Interned<ConstS>);
```
This now matches `Ty` and `Predicate` more closely, including using
pointer-based `eq` and `hash`.
Notable changes:
- `mk_const` now takes a `ConstS`.
- `Const` was copy, despite being 48 bytes. Now `ConstS` is not, so need a
we need separate arena for it, because we can't use the `Dropless` one any
more.
- Many `&'tcx Const<'tcx>`/`&Const<'tcx>` to `Const<'tcx>` changes
- Many `ct.ty` to `ct.ty()` and `ct.val` to `ct.val()` changes.
- Lots of tedious sigil fiddling.
This makes `Obligation` two words bigger, but avoids allocating a lot of
the time.
I previously tried this in #73983 and it didn't help much, but local
timings look more promising now.
This crate actually had a typo `'ctx` in one of its functions:
```diff
-pub fn same_type_modulo_infer(a: Ty<'tcx>, b: Ty<'ctx>) -> bool {
+pub fn same_type_modulo_infer<'tcx>(a: Ty<'tcx>, b: Ty<'tcx>) -> bool {
```
