Fallback to `static_impl_trait` for nice error message by peeking at the
return type and the lifetime type. Point at the return type instead of
the return expr/stmt in NLL mode.
HirIdification: kill off NodeId stragglers
The final stages of HirIdification (#57578).
This PR, along with https://github.com/rust-lang/rust/pull/59042, should finalize the HirIdification process (at least the more straightforward bits).
- replace `NodeId` with `HirId` in `trait_impls`
- remove all `NodeId`s from `borrowck`
- remove all `NodeId`s from `typeck`
- remove all `NodeId`s from `mir`
- remove `trait_auto_impl` (unused)
I would be cool to also remove `NodeId` from `hir::def::Def`, `middle::privacy::AccessLevel` and `hir::ItemId`, but I don't know if this is feasible.
I'll be happy to do more if I've missed anything.
[NLL] Remove `LiveVar`
The `LiveVar` type (and related) made it harder to reason about the code. It seemed as an abstraction that didn't bring any useful concept to the reader (when transitioning from the RFC theory to the actual implementation code).
It achieved a compactness in the vectors storing the def/use/drop information that was related only to the `LocalUseMap`. This PR went in the other direction and favored time over memory (but this decision can be easily reverted to the other side without reintroducing `LiveVar`).
What this PR aims at is to clarify that there's no significant transformation between the MIR `Local` and the `LiveVar` (now refactored as `live_locals: Vec<Local>`): we're just filtering (not mapping) the entire group of `Local`s into a meaningful subset that we should perform the liveness analysis on.
As a side note, there is no guarantee that the liveness analysis is performed only on (what the code calls) "live" variables, if the NLL facts are requested it will be performed on *any* variable so there can't be any assumptions on that regard. (Still, this PR didn't change the general naming convention to reduce the number of changes here and streamline the review process).
**Acceptance criteria:** This PR attempts to do only a minor refactoring and not to change the logic so it can't have any performance impact, particularly, it can't lose any of the significant performance improvement achieved in the great work done in https://github.com/rust-lang/rust/pull/52115.
r? @nikomatsakis
[NLL] Type check operations with pointer types
It seems these were forgotten about. Moving to `Rvalue::AddressOf` simplifies the coercions from references, but I want this to be fixed as soon as possible.
r? @pnkfelix
Type annotations are shared between the MIR of a function and the
promoted constants for that function, so keep them in the type checker
when we check the promoted MIR.
Function signatures with the `variadic` member set are actually
C-variadic functions. Make this a little more explicit by renaming the
`variadic` boolean value, `c_variadic`.
Use normal mutable borrows in matches
`ref mut` borrows are currently two-phase with NLL enabled. This changes them to be proper mutable borrows. To accommodate this, first the position of fake borrows is changed:
```text
[ 1. Pre-match ]
|
[ (old create fake borrows) ]
[ 2. Discriminant testing -- check discriminants ] <-+
| |
| (once a specific arm is chosen) |
| |
[ (old read fake borrows) ] |
[ 3. Create "guard bindings" for arm ] |
[ (create fake borrows) ] |
| |
[ 4. Execute guard code ] |
[ (read fake borrows) ] --(guard is false)-----------+
|
| (guard results in true)
|
[ 5. Create real bindings and execute arm ]
|
[ Exit match ]
```
The following additional changes are made to accommodate `ref mut` bindings:
* We no longer create fake `Shared` borrows. These borrows are no longer needed for soundness, just to avoid some arguably strange cases.
* `Shallow` borrows no longer conflict with existing borrows, avoiding conflicting access between the guard borrow access and the `ref mut` borrow.
There is some further clean up done in this PR:
* Avoid the "later used here" note for Shallow borrows (since it's not relevant with the message provided)
* Make any use of a two-phase borrow activate it.
* Simplify the cleanup_post_borrowck passes into a single pass.
cc #56254
r? @nikomatsakis
Extend `LocalUseMap`'s `IndexVec`s that track def/use/drop data to store the
original `Local` indexes and not the compacted `LiveVar` ones (favoring speed
and code simplicity over space). Remove the `NllLivenessMap` embedded inside it
since it's no longer needed to perform the `LiveVar`/`Local` conversion.
It was used in `compute_for_all_locals` to iterate only the `Local`s that need
liveness analysis (filtered through `compute`). Instead, explicitly extract that
reduced set (as `live_locals`) in `trace` and pass it to
`compute_for_all_locals`.
Change the variable type used in `compute_for_all_locals` from `LiveVar` to
`Local` and do the same for its helper functions (and the functions in
`LocalUseMap` they rely on):
* `add_defs_for` -> `LocalUseMap::defs`
* `compute_use_live_points_for` -> `LocalUseMap::uses`
* `compute_drop_live_points_for` -> `LocalUseMap::drops`
Push back the use of `LiveVar` to the `LocalUseMap` (where the other
`NllLivenessMap` remains embedded) functions which internally do the
`from_local` conversion.
