This was left over from when closure copy and clone were gated behind
feature flags.

Here, ExprKind::Use(P<Expr>) tweaks the drop order to act the
same way as '{ let _tmp = expr; _tmp }' does.

…feature gate

…ure, r=ollie27

Prevent failure in case no space left on device in rustdoc

Fixes rust-lang#59703.

r? @QuietMisdreavus

…nishearth

Fix index-page generation

Fixes rust-lang#60096.

The minifier was minifying crates name in `searchIndex` key position, which was a bit problematic for multiple reasons.

r? @rust-lang/rustdoc

Add Pin::{into_inner,into_inner_unchecked}

These functions are useful for unsafe code that needs to temporarily pull smart pointers out of the `Pin`, e.g. [the change that inspired them](Nemo157/futures-rs@b436178#diff-1a4e0ba4d1b539412ca576411ec6c7c2R258) is taking a `Pin<Box<dyn Future>>`, turning it into a `*mut dyn Future` via `Box::into_raw(unsafe { Pin::into_inner_unchecked(pin) })` then later dropping this via `drop(Pin::from(Box::from_raw(ptr)))`. This can be accomplished today via `{ let ptr = unsafe { Pin::get_unchecked_mut(pin.as_mut()) } as *mut dyn Future; mem::forget(pin); ptr }`, but this is far more complicated and loses out on the symmetry of using `Box::into_raw` and `Box::from_raw`.

I'll extend the documentation on what guarantees `into_inner_unchecked` needs to uphold once I get some feedback on whether this API is wanted or not.

r? @withoutboats

…=scalexm

Chalkify: Add builtin Copy/Clone

r? @nikomatsakis

…ps, r=oli-obk

Introduce hir::ExprKind::Use and employ in for loop desugaring.

In the `for $pat in $expr $block` desugaring we end with a `{ let _result = $match_expr; _result }` construct which makes `for` loops into a terminating scope and affects drop order. The construct was introduced in year 2015 by @pnkfelix in rust-lang#21984.

This PR replaces the construct with `hir::ExprKind::Use(P<hir::Expr>)` which is equivalent semantically but should hopefully be less costly in terms of compile time performance (to be determined).

This is extracted out of rust-lang@91b0abd from rust-lang#59288 for easier review and so that the perf implications wrt. `for`-loops can be measured.

r? @oli-obk

Implement Debug for Place using Place::iterate

r? @oli-obk

…, r=Centril

Derive Default instead of new in applicable lint

Closes rust-lang#60181

As far as I can see, at least within the `src/librustc_lint` directory this is the only place this is applicable.

…richton

Add feature-gate for f16c target feature

r? @alexcrichton

…=cramertj

Do not allow const generics to depend on type parameters

Fixes rust-lang#60264. In https://github.com/rust-lang/rust/pull/58191/files/b534cf992d0189032207f395c27ed092c89b40c7#diff-aeb0880081a991f34aef2ab889e1fb7a, it was suggested that there might be a better place for this error, but as this bug already affects stable, it's probably worth merging this now, and refactoring afterwards (I can open an issue for this).

Do not ICE when checking types against foreign fn

Fix rust-lang#60275.