Sometimes a simple goto misses the cleanup/unwind edges. Specifically, in the
case of infinite loops such as those introduced by a loop statement without any
other out edges. Analogous to TerminatorKind::FalseEdges; this new terminator
kind is used when we want borrowck to consider an unwind path, but real control
flow should never actually take it.

The comment previously implied that the true branch would result in the false
block. Fortunately the implementation is correct.

Update clippy and miri submodule

r? @Manishearth

cc @kennytm I needed to touch the miri submodule's Cargo.toml to make sure that clippy gets the newest compiletest_rs. This will not fix miri, but since I touched the miri submodule, will this PR fail?

miri is unfixable until #46882 is merged

Fix overflow when performing drop check calculations in NLL

Clearing out the infcx's region constraints after processing each type
ends up interacting badly with normalizing associated types. This commit
keeps all region constraints intact until the end of
TypeLivenessGenerator.add_drop_live_constraint, ensuring that normalized
types are able to re-use existing inference variables.

Fixes #47589

Fix ref-to-ptr coercions not working with NLL in certain cases

Implicit coercions from references to pointers were lowered to slightly
different Mir than explicit casts (e.g. 'foo as *mut T'). This resulted
in certain uses of self-referential structs compiling correctly when an
explicit cast was used, but not when the implicit coercion was used.

To fix this, this commit adds an outer 'Use' expr when applying a
raw-ptr-borrow adjustment. This makes the lowered Mir for coercions
identical to that of explicit coercions, allowing the original code to
compile regardless of how the raw ptr cast occurs.

Fixes #47722

Cleanup the shim code

 - We now write directly to `RETURN_PLACE` instead of creating intermediates
 - `tuple_like_shim` takes an iterator (used by #47867)
 - `tuple_like_shim` no longer relies on it being the first thing to create blocks, and uses relative block indexing in a cleaner way (necessary for #47867)
 - All the shim builders take `dest, src` arguments instead of hardcoding RETURN_PLACE

r? @EddyB

Rollup of 10 pull requests

- Successful merges: #47862, #47877, #47896, #47912, #47947, #47958, #47978, #47996, #47999, #47892
- Failed merges:

Turn `type_id` into a constant intrinsic

https://github.com/rust-lang/rust/issues/27745

The method `get_type_id` in `Any` is intended to support reflection. It's currently unstable in favor of using an associated constant instead. This PR makes the `type_id` intrinsic a constant intrinsic, the same as `size_of` and `align_of`, allowing `TypeId::of` to be a `const fn`, which will allow using an associated constant in `Any`.

Remove 'the this' in doc comments.

Run the `run-make` tests last, so more tests run on Windows when `make` is unavailable

ui tests: diff from old (expected) to new (actual) instead of backwards.

Previously `actual` was "old" and `expected` was "new" which resulted in `+` before `-`.
AFAIK all diff tools put `-` before `+`, which made the previous behavior *very confusing*.

r? @nikomatsakis

Clarify shared file handler behavior of File::try_clone.

Fixes https://github.com/rust-lang/rust/issues/46578.

Stabilize feature(match_beginning_vert)

With this feature stabilized, match expressions can optionally have a `|` at the beginning of each arm.

Reference PR: rust-lang-nursery/reference#231

Closes #44101

Use a range to identify SIGSEGV in stack guards

Previously, the `guard::init()` and `guard::current()` functions were
returning a `usize` address representing the top of the stack guard,
respectively for the main thread and for spawned threads.  The `SIGSEGV`
handler on `unix` targets checked if a fault was within one page below that
address, if so reporting it as a stack overflow.

Now `unix` targets report a `Range<usize>` representing the guard memory,
so it can cover arbitrary guard sizes.  Non-`unix` targets which always
return `None` for guards now do so with `Option<!>`, so they don't pay any
overhead.

For `linux-gnu` in particular, the previous guard upper-bound was
`stackaddr + guardsize`, as the protected memory was *inside* the stack.
This was a glibc bug, and starting from 2.27 they are moving the guard
*past* the end of the stack.  However, there's no simple way for us to know
where the guard page actually lies, so now we declare it as the whole range
of `stackaddr ± guardsize`, and any fault therein will be called a stack
overflow.  This fixes #47863.

Rollup merge of #47896 - zackmdavis:and_the_case_of_the_necessary_unnecessary_parens, r=nikomatsakis

decline to lint technically-unnecessary parens in function or method arguments inside of nested macros

In #46980 ("in which the unused-parens lint..." (14982db2)), the
unused-parens lint was made to check function and method arguments,
which it previously did not (seemingly due to oversight rather than
willful design). However, in #47775 and discussion thereon,
user–developers of Geal/nom and graphql-rust/juniper reported that the
lint was seemingly erroneously triggering on certain complex macros in
those projects. While this doesn't seem like a bug in the lint in the
particular strict sense that the expanded code would, in fact, contain
unncecessary parentheses, it also doesn't seem like the sort of thing
macro authors should have to think about: the spirit of the
unused-parens lint is to prevent needless clutter in code, not to give
macro authors extra heartache in the handling of token trees.

We propose the expediency of declining to lint unused parentheses in
function or method args inside of nested expansions: we believe that
this should eliminate the petty, troublesome lint warnings reported
in the issue, without forgoing the benefits of the lint in simpler
macros.

It seemed like too much duplicated code for the `Call` and `MethodCall`
match arms to duplicate the nested-macro check in addition to each
having their own `for` loop, so this occasioned a slight refactor so
that the function and method cases could share code—hopefully the
overall intent is at least no less clear to the gentle reader.

This is concerning #47775.

Do not ignore lifetime bounds in Copy impls

cc #29149

r? @nikomatsakis

Fix const evaluation ICE in rustdoc

Fixes #47860.

r? @EddyB

Do not enable ThinLTO on stable, beta, or nightly builds.

Fixes #45444

Update RLS and Rustfmt

r? @alexcrichton

rustc: prefer ParamEnvAnd and LayoutCx over tuples for LayoutOf.

This PR provides `tcx.layout_of(param_env.and(ty))` as the idiomatic replacement for the existing `(tcx, param_env).layout_of(ty)` and removes fragile (coherence-wise) layout-related tuple impls.

r? @nikomatsakis

Dist builds should always be as fast as we can make them, and since
those run on CI we don't care quite as much for the build being somewhat
slower. As such, we don't automatically enable ThinLTO on builds for the
dist builders.

Generator bugfixes

r? @nikomatsakis

Fixes https://github.com/rust-lang/rust/issues/46578.

elided lifetime

Closes #45992

Hey
Having a problem with my config so decided to make a WIP PR nevertheless. Will add some more tests.

Rollup of 10 pull requests

- Successful merges: #46156, #47829, #47842, #47898, #47914, #47916, #47919, #47942, #47951, #47973
- Failed merges: #47753

copy_nonoverlapping example: Fixed typo

The comment referred to a variable using an incorrect name. (it has probably been renamed since the comment was written, or the comment was copied elsewhere - I noted the example in libcore has the `tmp` name for the temporary variable.)

Tweak presentation on lifetime trait mismatch

 - On trait/impl method discrepancy, add label pointing at trait signature.
 - Point only at method definition when referring to named lifetimes on lifetime mismatch.
 - When the sub and sup expectations are the same, tweak the output to avoid repeated spans.

Fix #30790, CC #18759.

The comment referred to a variable using an incorrect name. (it has probably been renamed since the comment was written, or the comment was copied elsewhere - I noted the example in libcore has the `tmp` name for the temporary variable.)

Rollup merge of #47951 - GuillaumeGomez:sidebar-hover, r=QuietMisdreavus Fix ugly hover in sidebar In the sidebar, the elements under `Structs`, `Enums`... have an ugly hover if they're not selected. This fixes it. r? @QuietMisdreavus

Rollup merge of #47942 - estebank:macro-spans, r=nikomatsakis Minimize weird spans involving macro context Sometimes the parser attempts to synthesize spans from within a macro context with the span for the captured argument, leading to non-sensical spans with very bad output. Given that an incorrect span is worse than a partially incomplete span, when detecting this situation return only one of the spans without merging them. Fix #32072, #47778. CC #23480.

Rollup merge of #47919 - varkor:to_degrees-precision, r=rkruppe Use constant for 180/π in to_degrees The current `f32|f64.to_degrees` implementation uses a division to calculate `180/π`, which causes a loss of precision. Using a constant is still not perfect (implementing a maximally-precise algorithm would come with a high performance cost), but improves precision with a minimal change. As per the discussion in #29944, this fixes #29944 (the costs of improving the precision further would not outweigh the gains).

Rollup merge of #47916 - vmx:patch-2, r=kennytm Fix lang items box example code The `exchange_free` lang item is gone in favour of `box_free` [1]. Some warnings are also fixed by this commit. [1]: https://github.com/rust-lang/rust/commit/ca115dd083a1fe1d2b4892c5e50e49eb83ff1f3

Rollup merge of #47914 - etaoins:improve-char-escape-in-lexer-msg, r=petrochenkov Improve char escaping in lexer messages Currently ', " and \ are escaped as \', \" and \\ respectively. This leads to confusing messages such as `error: unknown start of token: \\` when encountering a single backslash. Fix by emitting printable ASCII characters directly. This will still escape \r, \n, \t and Unicode characters. Fixes #47902