cleanup: Remove `Spanned` where possible
It generally only makes sense on enums, otherwise it's more convenient to "flatten" it by adding a span field to the struct it wraps.
Rollup of 11 pull requests
Successful merges:
- #62984 (Add lint for excess trailing semicolons)
- #63075 (Miri: Check that a ptr is aligned and inbounds already when evaluating `*`)
- #63490 (libsyntax: cleanup and refactor `pat.rs`)
- #63507 (When needing type annotations in local bindings, account for impl Trait and closures)
- #63509 (Point at the right enclosing scope when using `await` in non-async fn)
- #63528 (syntax: Remove `DummyResult::expr_only`)
- #63537 (expand: Unimplement `MutVisitor` on `MacroExpander`)
- #63542 (Add NodeId for Arm, Field and FieldPat)
- #63543 (Merge Variant and Variant_)
- #63560 (move test that shouldn't be in test/run-pass/)
- #63570 (Adjust tracking issues for `MaybeUninit<T>` gates)
Failed merges:
r? @ghost
handle elision in async fn correctly
We now always make fresh lifetimne parameters for all elided
lifetimes, whether they are in the inputs or outputs. But then
we generate `'_` in the case of elided lifetimes from the outputs.
Example:
```rust
async fn foo<'a>(x: &'a u32) -> &u32 { .. }
```
becomes
```rust
type Foo<'a, 'b> = impl Future<Output = &'b u32>;
fn foo<'a>(x: &'a u32) -> Foo<'a, '_>
```
Fixes#63388
When encountering a boxed value as expected and a stack allocated value
that could be boxed to fulfill the expectation, like in the following
snippet, suggest `Box::new` wrapping.
We now always make fresh lifetimne parameters for all elided
lifetimes, whether they are in the inputs or outputs. But then
we generate `'_` in the case of elided lifetimes from the outputs.
Example:
```rust
async fn foo<'a>(x: &'a u32) -> &u32 { .. }
```
becomes
```rust
type Foo<'a, 'b> = impl Future<Output = &'b u32>;
fn foo<'a>(x: &'a u32) -> Foo<'a, '_>
```
Copy ty::Instance instead of passing by reference
ty::Instance is small and Copy, we should not be adding additional
indirection.
Fixes#63409.
r? @eddyb
Refactor and categorize lowering wrt. items / exprs
Split lowering into more files along the lines of "expression related" and "item related".
Also refactor huge methods into smaller ones.
A next step might be to introduce "type related" and merge patterns and statements combined with expressions into "value related". There's still more work to do but the PR was getting too big :)
r? @oli-obk
