I also added some comments explaining what is going on. In short, the
changes in question do not, in fact, affect the`TypeckTables` in any
semantic way. However, altering the order of lowering can cause it
appear to affect the `TypeckTables`: if we lower generics before the
body, then the `HirId` for things in the body will be affected. In
this case, we are now lowering the generics etc
*after* the body, so the hash no longer changes. This seems good.
Prevent fmt::Arguments from being shared across threads
Fixes#45197
This is a **breaking change**! Without doing this it's very easy to create race conditions.
There's probably a way to do this without breaking valid use cases, but it would require quite an overhaul of the formatting machinery.
rustdoc: include external files in documentation (RFC 1990)
Part of https://github.com/rust-lang/rfcs/pull/1990 (needs work on the error reporting, which i'm deferring to after this initial PR)
cc #44732
Also fixes#42760, because the prep work for the error reporting made it easy to fix that at the same time.
MIR-borrowck: Some minor fixes
- Remove parens when printing dereference (fix#45185)
- Change argument type of `autoderef` to `bool`
- Change argument type of `field_index` to `Field`
move closure kind, signature into `ClosureSubsts`
Instead of using side-tables, store the closure-kind and signature in the substitutions themselves. This has two key effects:
- It means that the closure's type changes as inference finds out more things, which is very nice.
- As a result, it avoids the need for the `freshen_closure_like` code (though we still use it for generators).
- It avoids cyclic closures calls.
- These were never meant to be supported, precisely because they make a lot of the fancy inference that we do much more complicated. However, due to an oversight, it was previously possible -- if challenging -- to create a setup where a closure *directly* called itself (see e.g. #21410).
We have to see what the effect of this change is, though. Needs a crater run. Marking as [WIP] until that has been assessed.
r? @arielb1
clean the Debug impl for CrateNum and DefId
Just a tiny quality-of-life improvement because I got tired of noisy debug logs.
```
before: DefId { krate: CrateNum(11), index: DefIndex(0:6) => foo[8787]::Mapper[0]::OtherType[0] } }
after: {crate11:0:6 ~ foo[8787]::Mapper[0]::OtherType[0]})
```
r? @michaelwoerister
dead code lint to say "never constructed" for variants
As reported in #19140, #44083, and #44565, some users were confused when
the dead-code lint reported an enum variant to be "unused" when it was
matched on (but not constructed). This wording change makes it clearer
that the lint is in fact checking for construction.
We continue to say "used" for all other items (it's tempting to say
"called" for functions and methods, but this turns out not to be
correct: functions can be passed as arguments and the dead-code lint
isn't special-casing that or anything).
Resolves#19140.
r? @pnkfelix
Optimize `read_to_end`.
This patch makes `read_to_end` use Vec's memory-growth pattern rather
than using a custom pattern.
This has some interesting effects:
- If memory is reserved up front, `read_to_end` can be faster, as it
starts reading at the buffer size, rather than always starting at 32
bytes. This speeds up file reading by 2x in one of my use cases.
- It can reduce the number of syscalls when reading large files.
Previously, `read_to_end` would settle into a sequence of 8192-byte
reads. With this patch, the read size follows Vec's allocation
pattern. For example, on a 16MiB file, it can do 21 read syscalls
instead of 2057. In simple benchmarks of large files though, overall
speed is still dominated by the actual I/O.
- A downside is that Read implementations that don't implement
`initializer()` may see increased memory zeroing overhead.
I benchmarked this on a variety of data sizes, with and without
preallocated buffers. Most benchmarks see no difference, but reading
a small/medium file with a pre-allocated buffer is faster.
rustbuild: distribute cargo-fmt alongside rustfmt
Not sure whether we want that nor if it's the right way to do so, but it feels quite weird to have rustfmt without cargo-fmt. Or are there other plans wrt that?
What do you think @nrc ?
update let-expressions hash test to use `except`
A part of #44924, this PR updated let-expressions test using `except`.
cc @michaelwoerister
r? @nikomatsakis
impl Trait Lifetime Handling
This PR implements the updated strategy for handling `impl Trait` lifetimes, as described in [RFC 1951](https://github.com/rust-lang/rfcs/blob/master/text/1951-expand-impl-trait.md) (cc #42183).
With this PR, the `impl Trait` desugaring works as follows:
```rust
fn foo<T, 'a, 'b, 'c>(...) -> impl Foo<'a, 'b> { ... }
// desugars to
exists type MyFoo<ParentT, 'parent_a, 'parent_b, 'parent_c, 'a, 'b>: Foo<'a, 'b>;
fn foo<T, 'a, 'b, 'c>(...) -> MyFoo<T, 'static, 'static, 'static, 'a, 'b> { ... }
```
All of the in-scope (parent) generics are listed as parent generics of the anonymous type, with parent regions being replaced by `'static`. Parent regions referenced in the `impl Trait` return type are duplicated into the anonymous type's generics and mapped appropriately.
One case came up that wasn't specified in the RFC: it's possible to write a return type that contains multiple regions, neither of which outlives the other. In that case, it's not clear what the required lifetime of the output type should be, so we generate an error.
There's one remaining FIXME in one of the tests: `-> impl Foo<'a, 'b> + 'c` should be able to outlive both `'a` and `'b`, but not `'c`. Currently, it can't outlive any of them. @nikomatsakis and I have discussed this, and there are some complex interactions here if we ever allow `impl<'a, 'b> SomeTrait for AnonType<'a, 'b> { ... }`, so the plan is to hold off on this until we've got a better idea of what the interactions are here.
cc #34511.
Fixes#44727.
