4501: Querify `importable_locations_in_crate` r=jonas-schievink a=jonas-schievink
This brings the time needed to compute the `add_missing_impl_members` assist down from ~5 minutes to 20 seconds on my test workload (which is editing within an impl of a MIR [`MutVisitor`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/mir/visit/trait.MutVisitor.html))
cc #4498
Co-authored-by: Jonas Schievink <jonasschievink@gmail.com>
4497: Create LowerCtx on the fly r=matklad a=edwin0cheng
Previously we create `LowerCtx` at the beginning of lowering, however, the hygiene content is in fact changing between macro expression expanding.
This PR change it to create the `LowerCtx` on the fly to fix above bug.
However, #4465 is not fixed by this PR, the goto-def is still not work yet. It only fixed the infer part.
Co-authored-by: Edwin Cheng <edwin0cheng@gmail.com>
4493: Provide builtin impls of Fn traits for fn-pointers r=flodiebold a=hban
Meant to be, but isn't actually a fix for #2880.
Consider this snippet:
```rust
use std::marker::PhantomData;
use std::ops::Deref;
struct Lazy<T, F/* = fn() -> T*/>(F, PhantomData<T>);
impl<T, F> Lazy<T, F> {
pub fn new(f: F) -> Lazy<T, F> {
Lazy(f, PhantomData)
}
}
impl<T, F: FnOnce() -> T> Deref for Lazy<T, F> {
type Target = T;
fn deref(&self) -> &T { todo!() }
}
fn test() {
let lazy1: Lazy<u32, _> = Lazy::new(|| 0u32);
let r1 = lazy1.to_string();
fn make_u32_fn() -> u32 { todo!() }
let make_u32_fn_ptr: fn() -> u32 = make_u32_fn;
let lazy2: Lazy<u32, _> = Lazy::new(make_u32_fn_ptr);
let r2 = lazy2.to_string();
}
```
* On current master:
* When type default is commented-out, `r1` is correctly inferred, `r2` in _{unknown}_.
* When type default is not commented-out, both `r1` and `r2` are _{unknown}_.
* With this PR:
* When type default is commented-out, both `r1` and `r2` are correctly inferred.
* When type default is not commented-out, both `r1` and `r2` are _{unknown}_.
Well, it's a improvement at least. I guess this thing with type defaults is a different problem.
I also tried add Fn impls for fn items, but wasn't successful. So this PR only adds those impls for fn pointers.
Co-authored-by: Hrvoje Ban <hban@users.noreply.github.com>
