…n lint

…about the lint

…hint

…riant

Required to resolve rust-lang#6562 rust-clippy issue.

It looks like `lev_distance` was used in a very old version of the function,
since it was written but never read, and Blame reports that it was added
before the `checkGenerics` function header itself.

`convertHTMLToPlaintext` is was removed by 768d5e9

Implement NOOP_METHOD_CALL lint

Implements the beginnings of rust-lang/lang-team#67 - a lint for detecting noop method calls (e.g, calling `<&T as Clone>::clone()` when `T: !Clone`).

This PR does not fully realize the vision and has a few limitations that need to be addressed either before merging or in subsequent PRs:
* [ ] No UFCS support
* [ ] The warning message is pretty plain
* [ ] Doesn't work for `ToOwned`

The implementation uses [`Instance::resolve`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/instance/struct.Instance.html#method.resolve) which is normally later in the compiler. It seems that there are some invariants that this function relies on that we try our best to respect. For instance, it expects substitutions to have happened, which haven't yet performed, but we check first for `needs_subst` to ensure we're dealing with a monomorphic type.

Thank you to ```@davidtwco,``` ```@Aaron1011,``` and ```@wesleywiser``` for helping me at various points through out this PR ❤️.

resolve: Reduce scope of `pub_use_of_private_extern_crate` deprecation lint

This lint was deny-by-default since July 2017, crater showed 7 uses on crates.io back then (rust-lang#42894 (comment)).

Unfortunately, the construction `pub use foo as bar` where `foo` is `extern crate foo;` was used by an older version `bitflags`, so turning it into an error causes too many regressions.
So, this PR reduces the scope of the lint instead of turning it into a hard error, and only turns some more rarely used components of it into errors.

…ramertj

Improved IO Bytes Size Hint

After trying to implement better `size_hint()` return values for `File` in [this PR](rust-lang#81044) and changing to implementing it for `BufReader` in [this PR](rust-lang#81052), I have arrived at this implementation that provides tighter bounds for the `Bytes` iterator of various readers including `BufReader`, `Empty`, and `Chain`.

Unfortunately, for `BufReader`, the size_hint only improves after calling `fill_buffer` due to it using the contents of the buffer for the hint. Nevertheless, the the tighter bounds  should result in better pre-allocation of space to handle the contents of the `Bytes` iterator.

Closes rust-lang#81052

… r=davidtwco

Add suggestion `.collect()` for iterators in iterators

Closes rust-lang#81584

```
error[E0515]: cannot return value referencing function parameter `y`
 --> main3.rs:4:38
  |
4 | ...                   .map(|y| y.iter().map(|x| x + 1))
  |                                -^^^^^^^^^^^^^^^^^^^^^^
  |                                |
  |                                returns a value referencing data owned by the current function
  |                                `y` is borrowed here
  |                                help: Maybe use `.collect()` to allocate the iterator
```

Added the suggestion: `help: Maybe use `.collect()` to allocate the iterator`

Fix underflow in specialized ZipImpl::size_hint

Fixes rust-lang#82282

… r=m-ou-se

Avoid unnecessary Vec construction in BufReader

As mentioned in rust-lang#80460, creating a `Vec` and calling `Vec::into_boxed_slice()` emits unnecessary calls to `realloc()` and `free()`. Updated the code to use `Box::new_uninit_slice()` to create a boxed slice directly. I think this also makes it more explicit that the initial contents of the buffer are uninitialized.

r? ``@m-ou-se``

Add {BTreeMap,HashMap}::try_insert

`{BTreeMap,HashMap}::insert(key, new_val)` returns `Some(old_val)` if the key was already in the map. It's often useful to assert no duplicate values are inserted.

We experimented with `map.insert(key, val).unwrap_none()` (rust-lang#62633), but decided that that's not the kind of method we'd like to have on `Option`s.

`insert` always succeeds because it replaces the old value if it exists. One could argue that `insert()` is never the right method for panicking on duplicates, since already handles that case by replacing the value, only allowing you to panic after that already happened.

This PR adds a `try_insert` method that instead returns a `Result::Err` when the key already exists. This error contains both the `OccupiedEntry` and the value that was supposed to be inserted. This means that unwrapping that result gives more context:
```rust
    map.insert(10, "world").unwrap_none();
    // thread 'main' panicked at 'called `Option::unwrap_none()` on a `Some` value: "hello"', src/main.rs:8:29
```

```rust
    map.try_insert(10, "world").unwrap();
    // thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value:
    // OccupiedError { key: 10, old_value: "hello", new_value: "world" }', src/main.rs:6:33
```

It also allows handling the failure in any other way, as you have full access to the `OccupiedEntry` and the value.

`try_insert` returns a reference to the value in case of success, making it an alternative to `.entry(key).or_insert(value)`.

r? ```@Amanieu```

Fixes rust-lang/rfcs#3092

Add assert_matches macro.

This adds `assert_matches!(expression, pattern)`.

Unlike the other asserts, this one ~~consumes the expression~~ may consume the expression, to be able to match the pattern. (It could add a `&` implicitly, but that's noticable in the pattern, and will make a consuming guard impossible.)

See rust-lang#62633 (comment)

This re-uses the same `left: .. right: ..` output as the `assert_eq` and `assert_ne` macros, but with the pattern as the right part:

assert_eq:
```
assertion failed: `(left == right)`
  left: `Some("asdf")`,
 right: `None`
```
assert_matches:
```
assertion failed: `(left matches right)`
  left: `Ok("asdf")`,
 right: `Err(_)`
```

cc ```@cuviper```

…_to_Default_trait, r=oli-obk

Add diagnostic item to `Default` trait

This PR adds diagnostic item to `Default` trait to be used by rust-lang/rust-clippy#6562 issue.
Also fixes the obsolete path to the `symbols.rs` file in the comment.

…umeGomez

Remove unused code from main.js

It looks like `lev_distance` was used in a very old version of the function, since it was written but never read, and Blame reports that it was added before the `checkGenerics` function header itself.

`convertHTMLToPlaintext` is was removed by 768d5e9