Signed-off-by: NGabriel Smith <ga29smith@gmail.com>

Co-Authored-By: NGabriel Smith <yodaldevoid@users.noreply.github.com>

Co-Authored-By: NGabriel Smith <yodaldevoid@users.noreply.github.com>

Co-Authored-By: NGabriel Smith <yodaldevoid@users.noreply.github.com>

Co-Authored-By: NGabriel Smith <yodaldevoid@users.noreply.github.com>

Co-Authored-By: NGabriel Smith <yodaldevoid@users.noreply.github.com>

Co-Authored-By: NGabriel Smith <yodaldevoid@users.noreply.github.com>

Co-Authored-By: NGabriel Smith <yodaldevoid@users.noreply.github.com>

Co-Authored-By: NGabriel Smith <yodaldevoid@users.noreply.github.com>

Co-Authored-By: NGabriel Smith <yodaldevoid@users.noreply.github.com>

Co-Authored-By: NGabriel Smith <yodaldevoid@users.noreply.github.com>

Co-Authored-By: NGabriel Smith <yodaldevoid@users.noreply.github.com>

Co-Authored-By: NGabriel Smith <yodaldevoid@users.noreply.github.com>

Co-Authored-By: NGabriel Smith <yodaldevoid@users.noreply.github.com>

Co-Authored-By: NGabriel Smith <yodaldevoid@users.noreply.github.com>

Co-Authored-By: NGabriel Smith <yodaldevoid@users.noreply.github.com>

Co-Authored-By: NGabriel Smith <yodaldevoid@users.noreply.github.com>

Co-Authored-By: NGabriel Smith <yodaldevoid@users.noreply.github.com>

Rollup of 7 pull requests

Successful merges:

 - #60287 (Use references for variances_of)
 - #60327 (Search for incompatible universes in borrow errors)
 - #60330 (Suggest using an inclusive range instead of an exclusive range when the endpoint overflows by 1)
 - #60366 (build-gcc: Create missing cc symlink)
 - #60369 (Support ZSTs in DispatchFromDyn)
 - #60404 (Implement `BorrowMut<str>` for `String`)
 - #60417 (Rename hir::ExprKind::Use to ::DropTemps and improve docs.)

Failed merges:

r? @ghost

rustdoc: remove def_ctor hack.

~~No longer necessary since we have `describe_def`.~~

Turns out `def_ctor` was used in conjunction with abusing `tcx.type_of(def_id)` working on both type definitions and `impl`s (specifically, of builtin types), but also reimplementing a lot of the logic that `Clean` already provides on `Ty` / `ty::TraitRef`.

The first commit now does the minimal refactor to keep it working, while the second commit contains the rest of the refactor I started (parts of which I'm not sure we need to keep).

Split `CommonTypes` into `CommonTypes` and `CommonLifetimes`

The so-called "`CommonTypes`" contains more than just types.

r? @EddyB

Rename hir::ExprKind::Use to ::DropTemps and improve docs.

Addresses https://github.com/rust-lang/rust/pull/60225#discussion_r279797691.

r? @oli-obk

cc @EddyB @Manishearth

Implement `BorrowMut<str>` for `String`

Closes rust-lang/rfcs#1282.

Support ZSTs in DispatchFromDyn

Allows to use ZSTs with 1 byte alignment in `DispatchFromDyn` implementation. This is required for `Box<T, A: Alloc>`

cc #58457

build-gcc: Create missing cc symlink

This PR mostly fixes build error caused by using rustc docker images
to build [rustup][1] (with the error: ``linker `cc` not found``).

I don't know why gcc build script doesn't install cc hard link by default.
In build log, with `make SHELL='sh -x' install`, gcc build script installs c++
hard link but not `cc` one:

```bash
if test "" != "yes" ; then \
  rm -f /rustroot/bin/g++; \
  /usr/bin/install -c xg++ /rustroot/bin/g++; \
  chmod a+x /rustroot/bin/g++; \
  rm -f /rustroot/bin/c++; \
  ( cd /rustroot/bin && \
    ln g++ c++ ); \
  if [ -f cc1plus ] ; then \
    if [ ! -f g++-cross ] ; then \
      rm -f /rustroot/bin/x86_64-unknown-linux-gnu-g++; \
      ( cd /rustroot/bin && \
        ln g++ x86_64-unknown-linux-gnu-g++ ); \
      rm -f /rustroot/bin/x86_64-unknown-linux-gnu-c++; \
      ( cd /rustroot/bin && \
        ln c++ x86_64-unknown-linux-gnu-c++ ); \
    fi ; \
  fi; \
fi
```

This might be fixed downstream by manually creating cc hard link
or setting `RUSTFLAGS="-C linker=gcc"` as [suggested by @mati865][2].
But I find it better to fix it upstream in this PR.

[1]: https://github.com/rust-lang/rustup.rs/pull/1815
[2]: https://github.com/rust-lang/rustup.rs/pull/1815#discussion_r279192797

Suggest using an inclusive range instead of an exclusive range when the endpoint overflows by 1

Fixes https://github.com/rust-lang/rust/issues/47213.

Search for incompatible universes in borrow errors

If we have a borrow that has to live for `'static` we need to check for
any regions in incompatible universes when trying to find the cause.

closes #60274

Use references for variances_of

Based on https://github.com/rust-lang/rust/pull/60280.

cc @varkor
r? @EddyB

Fix indexing issue for const parameter invariance

We were previously not taking account of the parent parameters.

r? @EddyB
cc @Zoxc

Debug-print error when using rtunwrap

When I added this macro a while back I didn't have a way to make it print the failure for all types that you might want to unwrap. Now, I came up with a solution.

 PGO: Add a run-make test that makes sure that PGO profiling data is used by the compiler during optimizations.

From the tests comment section:
```
# This test makes sure that PGO profiling data leads to cold functions being
# marked as `cold` and hot functions with `inlinehint`.
# The test program contains an `if` were actual execution only ever takes the
# `else` branch. Accordingly, we expect the function that is never called to
# be marked as cold.
```

r? @alexcrichton