Convert warning about *const _ to a future-compat lint

[mikeyhew]

#46664 was merged before I could convert the soft warning about method lookup on *const _ into a future-compatibility lint. This PR makes that change.

fixes #46837
tracking issue for the future-compatibility lint: #46906

r? @arielb1

[arielb1]

Needs a rebase

[arielb1]

r=me with a rebase

[mikeyhew]

Oh true, I had a hunch this would cause an error because of deny(warnings). I'll update libstd and push again

[arielb1]

Still errors in rustc_data_structures

[CAD97]

These further changes got my local copy (x86_64-pc-windows-msvc) to pass a local test:

EDIT: (Well, most of one. Didn't have Make installed yet so those tests failed and prevented the rustdoc tests apparently)

src/librustc_data_structures/array_vec.rs

-141        let arr = &mut self.values as &mut [ManuallyDrop<_>];
+141        let arr = &mut self.values as &mut [ManuallDrop<<A as Array>::Element>];
...
-263        let arr = &mut source_array_vec.values as &mut [ManualyDrop<_>];
+263        let arr =
+264            &mut source_array_vec.values as &mut [ManuallyDrop<<A as Array>::Element>];

src/libstd/sys/windows/fs.rs

-773      let buf = &mut (*db).ReparseTarget as *mut _;
+773        let buf = &mut (*db).ReparseTarget as *mut c::WCHAR;

commit at CAD97@0563701 if you just want to add that to the PR.

[mikeyhew]

@CAD97 thanks! I develop on OSX, so would have had to wait for AppVeyor to fail before I could fix the windows errors

[arielb1]

doc test failure:

[01:12:44] ---- ptr.rs - ptr::*mut T::copy_from (line 1827) stdout ----
[01:12:44] 	error: the type of this value must be known in this context
[01:12:44]   --> ptr.rs:10:22
[01:12:44]    |
[01:12:44] 10 |     dst.as_mut_ptr().copy_from(ptr, elts);
[01:12:44]    |                      ^^^^^^^^^
[01:12:44]    |
[01:12:44] note: lint level defined here
[01:12:44]   --> ptr.rs:1:9
[01:12:44]    |
[01:12:44] 1  | #![deny(warnings)]
[01:12:44]    |         ^^^^^^^^
[01:12:44]    = note: #[deny(tyvar_behind_raw_pointer)] implied by #[deny(warnings)]
[01:12:44]    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
[01:12:44]    = note: for more information, see issue #46906 <https://github.com/rust-lang/rust/issues/46906>
[01:12:44] 
[01:12:44] thread 'rustc' panicked at 'couldn't compile the test', /checkout/src/librustdoc/test.rs:286:12
[01:12:44] note: Run with `RUST_BACKTRACE=1` for a backtrace.
[01:12:44] 
[01:12:44] ---- ptr.rs - ptr::*mut T::copy_from_nonoverlapping (line 1866) stdout ----
[01:12:44] 	error: the type of this value must be known in this context
[01:12:44]   --> ptr.rs:10:22
[01:12:44]    |
[01:12:44] 10 |     dst.as_mut_ptr().copy_from_nonoverlapping(ptr, elts);
[01:12:44]    |                      ^^^^^^^^^^^^^^^^^^^^^^^^
[01:12:44]    |
[01:12:44] note: lint level defined here
[01:12:44]   --> ptr.rs:1:9
[01:12:44]    |
[01:12:44] 1  | #![deny(warnings)]
[01:12:44]    |         ^^^^^^^^
[01:12:44]    = note: #[deny(tyvar_behind_raw_pointer)] implied by #[deny(warnings)]
[01:12:44]    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
[01:12:44]    = note: for more information, see issue #46906 <https://github.com/rust-lang/rust/issues/46906>
[01:12:44] 
[01:12:44] thread 'rustc' panicked at 'couldn't compile the test', /checkout/src/librustdoc/test.rs:286:12
[01:12:44] 
[01:12:44] 
[01:12:44] failures:
[01:12:44]     ptr.rs - ptr::*mut T::copy_from (line 1827)
[01:12:44]     ptr.rs - ptr::*mut T::copy_from_nonoverlapping (line 1866)

[arielb1]

@bors r+

[bors]

📌 Commit 60e6629 has been approved by arielb1

[bors]

⌛ Testing commit 60e6629 with merge a6fc844...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: arielb1
Pushing a6fc844 to master...