This span is unused and is superseded by capture_kind_expr_id in CaptureInfo

unify typeck of hir::Local and hir::Let
remove extraneous pub(crate/super)

example: let x: String = String::new().into();

Liveness analysis for generators assumes that execution always continues
normally after a yield point, not accounting for the fact that generator
could be dropped before completion.

If generators captures any variables by reference, those variables could
be used within a generator, or when the generator completes, but also
after each yield point in the case the generator is dropped.

Account for the case when generator is dropped after yielding, but
before running to the completion. This effectively considers all
variables captured by reference to be used after a yield point.

In most calling conventions, accessing function parameters may require
stack access. However, naked functions have no assembly prelude to set
up stack access.  This is why naked functions may only contain a single
`asm!()` block. All parameter access is done inside the `asm!()` block,
so we cannot validate the liveness of the input parameters. Therefore,
we should disable the lint for naked functions.

rust-lang/rfcs#2774
rust-lang/rfcs#2972

make changes to liveness to use closure_min_captures

use different span

borrow check uses new structures

rename to CapturedPlace

stop using upvar_capture in regionck

remove the bridge

cleanup from rebase + remove the upvar_capture reference from mutability_errors.rs

remove line from livenes test

make our unused var checking more consistent

update tests

adding more warnings to the tests

move is_ancestor_or_same_capture to rustc_middle/ty

update names to reflect the closures

add FIXME

check that all captures are immutable borrows before returning

add surrounding if statement like the original

move var out of the loop and rename
Co-authored-by: NLogan Mosier <logmosier@gmail.com>
Co-authored-by: NRoxane Fruytier <roxane.fruytier@hotmail.com>

Fix #82488

See https://rust-lang.zulipchat.com/#narrow/stream/182449-t-compiler.2Fhelp/topic/Is.20there.20a.20symbol.20for.20the.20empty.20string.3F/near/220054471
for context.

The liveness uses a mixed representation of RWUs based on the
observation that most of them have invalid reader and invalid
writer. The packed variant uses 32 bits and unpacked 96 bits.
Unpacked data contains reader live node and writer live node.

Since live nodes are used only to determine their validity,
RWUs can always be stored in a packed form with four bits for
each: reader bit, writer bit, used bit, and one extra padding
bit to simplify packing and unpacking operations.

No functional changes intended.

Perform liveness analysis for every body instead of limiting it to fns.