Co-authored-by: Peter Todd <pete@petertodd.org>

Co-authored-by: David Tolnay <dtolnay@gmail.com>

For example, if you had this code:

    fn foo(x: i32, y: f32) -> f32 {
        x * y
    }

You would get this error:

    error[E0277]: cannot multiply `f32` to `i32`
     --> src/lib.rs:2:7
      |
    2 |     x * y
      |       ^ no implementation for `i32 * f32`
      |
      = help: the trait `Mul<f32>` is not implemented for `i32`

However, that's not usually how people describe multiplication. People
usually describe multiplication like how the division error words it:

    error[E0277]: cannot divide `i32` by `f32`
     --> src/lib.rs:2:7
      |
    2 |     x / y
      |       ^ no implementation for `i32 / f32`
      |
      = help: the trait `Div<f32>` is not implemented for `i32`

So that's what this change does. It changes this:

    error[E0277]: cannot multiply `f32` to `i32`
     --> src/lib.rs:2:7
      |
    2 |     x * y
      |       ^ no implementation for `i32 * f32`
      |
      = help: the trait `Mul<f32>` is not implemented for `i32`

To this:

    error[E0277]: cannot multiply `i32` by `f32`
     --> src/lib.rs:2:7
      |
    2 |     x * y
      |       ^ no implementation for `i32 * f32`
      |
      = help: the trait `Mul<f32>` is not implemented for `i32`

Previously the title would be

    lib.rs.html -- source

if `lib.rs` was the actual source filename. Now the title is

    lib.rs – source

(note the en dash).

Even in the PR that introduced this comment, it does not seem like these locals are actually ignored -- just their `source_info` is adjusted:
https://github.com/rust-lang/rust/pull/44700/files#diff-ae2f3c7e2f9744f7ef43e96072b10e98d4e3fe74a3a399a3ad8a810fbe56c520R139

…afety

Fix rust-lang#77598.

…, r=dtolnay

Add Pin::static_ref, static_mut.

This adds `Pin::static_ref` and `Pin::static_mut`, which convert a static reference to a pinned static reference.

Static references are effectively already pinned, as what they refer to has to live forever and can never be moved.

---

Context: I want to update the `sys` and `sys_common` mutexes/rwlocks/condvars to use `Pin<&self>` in their functions, instead of only warning in the unsafety comments that they may not be moved. That should make them a little bit less dangerous to use. Putting such an object in a `static` (e.g. through `sys_common::StaticMutex`) fulfills the requirements about never moving it, but right now there's no safe way to get a `Pin<&T>` to a `static`. This solves that.

Tweak "object unsafe" errors

CC rust-lang#77598.

BTreeMap: split off most code of remove and split_off

Putting map.rs on a diet, in addition to rust-lang#77851.
r? @dtolnay

…or, r=estebank

Improve wording of "cannot multiply" type error

For example, if you had this code:

    fn foo(x: i32, y: f32) -> f32 {
        x * y
    }

You would get this error:

    error[E0277]: cannot multiply `f32` to `i32`
     --> src/lib.rs:2:7
      |
    2 |     x * y
      |       ^ no implementation for `i32 * f32`
      |
      = help: the trait `Mul<f32>` is not implemented for `i32`

However, that's not usually how people describe multiplication. People
usually describe multiplication like how the division error words it:

    error[E0277]: cannot divide `i32` by `f32`
     --> src/lib.rs:2:7
      |
    2 |     x / y
      |       ^ no implementation for `i32 / f32`
      |
      = help: the trait `Div<f32>` is not implemented for `i32`

So that's what this change does. It changes this:

    error[E0277]: cannot multiply `f32` to `i32`
     --> src/lib.rs:2:7
      |
    2 |     x * y
      |       ^ no implementation for `i32 * f32`
      |
      = help: the trait `Mul<f32>` is not implemented for `i32`

To this:

    error[E0277]: cannot multiply `i32` by `f32`
     --> src/lib.rs:2:7
      |
    2 |     x * y
      |       ^ no implementation for `i32 * f32`
      |
      = help: the trait `Mul<f32>` is not implemented for `i32`

…=jyn514

rustdoc: Show the correct source filename in page titles, without `.html`

Previously the title would be

    lib.rs.html -- source

if `lib.rs` was the actual source filename. Now the title is

    lib.rs - source

fix static_ptr_ty for foreign statics

Cc rust-lang#74840

This does not fix that issue but fixes a problem in `static_ptr_ty` that we noticed while discussing that issue. I also added and updated a few comments. The one about `internal` locals being ignored does not seem to have been true [even in the commit that introduced it](https://github.com/rust-lang/rust/pull/44700/files#diff-ae2f3c7e2f9744f7ef43e96072b10e98d4e3fe74a3a399a3ad8a810fbe56c520R139).

r? @oli-obk

…r=petrochenkov

Inline const followups

r? @petrochenkov

Follow ups of rust-lang#77124