…n check_overloaded_binop

It's redundant because there's already a selector `.source nav.sub` with
exactly the same margin-left at line 796.

This selector was added in 1e98fb1, along
with an identical desktop selector, but that desktop selector was removed in
6a5f8b1 as part of a larger simplification.

… LHS

Implements rust-lang#101400.

…imulacrum

Fix internal doc link

The doc link from `DedupSortedIter` to `BTreeMap::bulk_build_from_sorted_iter` was broken when building internal documentation,

This prevented me from building internal documentation locally:

```
R:\Rust\rust> $env:RUSTDOCFLAGS="--document-private-items"
R:\Rust\rust> x doc library/std --open --stage 0
Building rustbuild
   Compiling bootstrap v0.0.0 (R:\Rust\rust\src\bootstrap)
    Finished dev [unoptimized] target(s) in 3.15s
Documenting stage0 std (x86_64-pc-windows-msvc)
 Documenting core v0.0.0 (R:\Rust\rust\library\core)
    Finished release [optimized] target(s) in 36.42s
    Checking core v0.0.0 (R:\Rust\rust\library\core)
    Checking rustc-std-workspace-core v1.99.0 (R:\Rust\rust\library\rustc-std-workspace-core)
    Checking compiler_builtins v0.1.79
 Documenting alloc v0.0.0 (R:\Rust\rust\library\alloc)
error: unresolved link to `BTreeMap::bulk_build_from_sorted_iter`
 --> library\alloc\src\collections\btree\dedup_sorted_iter.rs:6:15
  |
6 | /// Used by [`BTreeMap::bulk_build_from_sorted_iter`].
  |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no item named `BTreeMap` in scope
  |
  = note: `-D rustdoc::broken-intra-doc-links` implied by `-D warnings`

error: could not document `alloc`
```

…omcc

updated description of File struct in std::fs

I've seen several folks confused by the description of `std::fs::File` as "A reference to an open file on the filesystem." Apparently the word `reference` is sometimes taken to mean a Rust `&` reference, leading to confusion. Here's a recent representative [Reddit thread](https://www.reddit.com/r/rust/comments/x4k0lv/comment/imxu7v2/?utm_source=share&utm_medium=web2x&context=3), but I've seen this before as well.

This patch changes the description to "An object providing access to an open file on the filesystem." Hopefully this is clearer.

…e1-dead

Don't delay invalid LHS bug unless it will be covered by an error in `check_overloaded_binop`

Fixes rust-lang#101376

Forbid mixing `System` with direct sytem allocator calls

e.g. [on windows](https://github.com/rust-lang/rust/blob/dec689432fac6720b2f18101ac28a21add98b1b8/library/std/src/sys/windows/alloc.rs#L129-L178), trying to mix `System::alloc` and `HeapFree` will not work because of the extra work done to serve higher alignments.

…-sidebar-sub, r=GuillaumeGomez

rustdoc: remove redundant mobile-sized `.source nav:not(.sidebar).sub`

It's redundant because there's already a selector `.source nav.sub` with exactly the same margin-left at [line 796].

[line 796]: https://github.com/rust-lang/rust/blob/84f0c3f79a85329dd79a54694ff8a7f427c842e9/src/librustdoc/html/static/css/rustdoc.css#L796

This selector was added in 1e98fb1, along with an identical desktop selector, but that desktop selector was removed in 6a5f8b1 as part of a larger simplification.

Make `char::is_lowercase` and `char::is_uppercase` const

Implements rust-lang#101400.

…est, r=Dylan-DPC

Remove duplicated test (superseeded by search-form-elements.goml)

I realized it when I worked on rust-lang#101348. The checks are more complete in `search-form-elements.goml` (for example [here](https://github.com/rust-lang/rust/blob/master/src/test/rustdoc-gui/search-form-elements.goml#L12-L29)).

r? `@Dylan-DPC`