Add lint: from_iter_instead_of_collect

Fixes #5679

This implements lint for `::from_iter()` from #5679 not the general issue (`std::ops::Add::add`, etc.).
This lint checks if expression is function call with `from_iter` name and if it's implementation of the `std::iter::FromIterator` trait.

changelog: Introduce  from_iter_instead_of_collect lint

Especially on CI, where cross-compiling is common and single builder may end up
with multiple hosts and multiple targets, it can be annoying to scroll back to
the nearest start of test marker. This prints out a summary of the test suite
being run directly in compiletest.

Add lint 'ref_option_ref' #1377

This lint checks for usage of `&Option<&T>` which can be simplified as `Option<&T>` as suggested in #1377.

This WIP PR is here to get feedback on the lint as there's more cases to be handled:
* statics/consts,
* associated types,
* type alias,
* function/method parameter/return,
* ADT definitions (struct/tuple struct fields, enum variants)

changelog: Add 'ref_option_ref' lint

…eywiser

Properly handle lint spans after MIR inlining

The first commit shows what happens when we apply mir inlining and then cause lints on the inlined MIR.
The second commit fixes that.

r? `@wesleywiser`

add manual_ok_or lint

Implements partially #5923

changelog: add lint manual_ok_or

Add support for SHA256 source file hashing

Adds support for `-Z src-hash-algorithm sha256`, which became available in LLVM 11.

Using an older version of LLVM will cause an error `invalid checksum kind` if the hash algorithm is set to sha256.

r? `@eddyb`
cc #70401 `@est31`

Sync rustc_codegen_cranelift

This fixes bootstrapping of rustc using cg_clif again. It regressed a while before #77975 got merged.

Fixes https://github.com/bjorn3/rustc_codegen_cranelift/issues/743

…pl, r=estebank

Improve errors about #[deprecated] attribute

This change:

1. Turns `#[deprecated]` on a trait impl block into an error, which fixes #78625;
2. Changes these and other errors about `#[deprecated]` to use the span of the attribute instead of the item; and
3. Turns this error into a lint, to make sure it can be capped with `--cap-lints` and doesn't break any existing dependencies.

Can be reviewed per commit.

---
Example:
```rust
struct X;

#[deprecated = "a"]
impl Default for X {
    #[deprecated = "b"]
    fn default() -> Self {
        X
    }
}
```

Before:
```
error: This deprecation annotation is useless
 --> src/main.rs:6:5
  |
6 | /     fn default() -> Self {
7 | |         X
8 | |     }
  | |_____^
```

After:
```
error: this `#[deprecated]' annotation has no effect
 --> src/main.rs:3:1
  |
3 | #[deprecated = "a"]
  | ^^^^^^^^^^^^^^^^^^^ help: try removing the deprecation attribute
  |
  = note: `#[deny(useless_deprecated)]` on by default

error: this `#[deprecated]' annotation has no effect
 --> src/main.rs:5:5
  |
5 |     #[deprecated = "b"]
  |     ^^^^^^^^^^^^^^^^^^^ help: try removing the deprecation attribute
```

Corrected suggestion for generic parameters in `function_item_references` lint

This commit handles functions with generic type parameters like you pointed out as well as const generics. Also this is probably a minor thing, but the type alias you used in the example doesn't show up so the suggestion right now would be `size_of::<[u8; 16]> as fn() ->`. This is because the lint checker works with MIR instead of HIR. I don't think we can get the alias at that point, but let me know if I'm wrong and there's a way to fix this. Also I put you as the reviewer, but I'm not sure if you want to review it or if it makes more sense to ask one of the original reviewers of this lint.
closes #78571

Suggest library/std when running all stage 0 tests

r? ``@Mark-Simulacrum``
cc ``@ijackson``

For context, this came out of a discord conversation where ``@ijackson`` was running `test --stage 1` when they were only adding doc-tests to the standard library.

Show more error information in lldb_batchmode

Even more information to try and debug #78665.

…Simulacrum

Fix panic in bootstrap for non-workspace path dependencies.

If you add a `path` dependency to a `Cargo.toml` that is located outside of the workspace, then the `in_tree_crates` function can panic because it finds a path dependency that is not defined (since it uses `cargo metadata --no-deps`).  This fixes it by skipping over those entries, which are usually not things you select on the command-line.

Fixes #78617

Rollup of 7 pull requests

Successful merges:

 - #77950 (Add support for SHA256 source file hashing)
 - #78624 (Sync rustc_codegen_cranelift)
 - #78626 (Improve errors about #[deprecated] attribute)
 - #78659 (Corrected suggestion for generic parameters in `function_item_references` lint)
 - #78687 (Suggest library/std when running all stage 0 tests)
 - #78699 (Show more error information in lldb_batchmode)
 - #78709 (Fix panic in bootstrap for non-workspace path dependencies.)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

This adds a binary called `x` in `src/tools/x`. All it does is check the
current directory and its ancestors for a file called `x.py`, and if it
finds one, runs it.

By installing x, you can easily `x.py` from any subdirectory.

It can be installed globally with `cargo install --path src/tools/x`

…, r=flip1995

Clarify allow/warn/deny documentation.  Remove enable/disable.

Disable and enable when not specifically explained were not clear to me
as an English language speaker, but I was able to figure it out fairly
easily due to the examples having A/W, which I assumed meant `allow` and
`warn`.  I removed both words to be sure it was clear as well as
extending the note on what deny means.  It now includes a statement on
exactly what each word means.

Documentation only update.

*Please keep the line below*
changelog: none

Use const sym where possible

I ran a regex search and replace to use const `sym` values where possible. This should give some performance boost by avoiding string interning at runtime.

Con: It is not as consistent as always using `sym!`.

I also changed an internal lint to suggest using `sym::{}`, making an assumption that this will always work for diagnostic items.

changelog: none

…hat caused the performance regression

This is cheaper than creating a null-`ScalarInt` and comparing
and then just throwing it away.

Co-authored-by: Ralf Jung <post@ralfj.de>

Also includes:
- Cell::into_inner
- RefCell::into_inner
- Atomic*::into_inner

The comment has become outdated as the array_impl macro
has been removed.

Use reparsed `TokenStream` if we captured any inner attributes

Fixes #78675

We now bail out of `prepend_attrs` if we ended up capturing any inner
attributes (which can happen in several places, due to token capturing
for `macro_rules!` arguments.

filter_next
manual_strip
redundant_static_lifetimes
single_char_pattern
unnecessary_cast
unused_unit
op_ref
redundant_closure
useless_conversion

…hus we use `to_bits` with the correct size

Co-authored-by: Ralf Jung <post@ralfj.de>

Co-authored-by: Ralf Jung <post@ralfj.de>

Refactorings in preparation for const value trees

cc #72396

This PR changes the `Scalar::Bits { data: u128, size: u8 }` variant to `Scalar::Bits(ScalarInt)` where `ScalarInt` contains the same information, but is `repr(packed)`. The reason for using a packed struct is to allow enum variant packing to keep the original size of `Scalar` instead of adding another word to its size due to padding.
Other than that the PR just gets rid of all the inspection of the internal fields of `Scalar::Bits` which were frankly scary. These fields have invariants that we need to uphold and we can't do that without making the fields private.

r? `@ghost`

Codegen: Query span as late as possible

Remove legacy promote-release support from build-manifestg

Now that we're not running the [legacy `promote-release`](https://github.com/rust-lang/rust-central-station/tree/master/promote-release) anymore, this PR removes support from it from `bootstrap` and `build-manifest`.

r? `@Mark-Simulacrum`

Rustup

changelog: none

r? `@ghost`

Add lint for 'field_reassign_with_default` #568

changelog: Add lint for field_reassign_with_default that checks if mutable object + field modification is used to edit a binding initialized with Default::default() instead of struct constructor.

Fixes #568

Notes:
- Checks for reassignment of one or more fields of a binding initialized with Default::default().
- Implemented using EarlyLintPass, might be future proofed better with LateLintPass.
- Does not trigger if Default::default() is used via another type implementing Default.
- This is a re-open of [PR#4761](rust-lang/rust-clippy#4761), but I couldn't figure out how to re-open that one so here's a new one with the requested changes :S

…_unit, r=ebroto

Fix suggestion to add unneeded space in `unused_unit`

Fix rust-lang/rust-clippy#6230

changelog: Fix suggestion to add unneeded space in `unused_unit`

…sakis

Provide diagnostic suggestion in ExprUseVisitor Delegate

The [Delegate trait](https://github.com/rust-lang/rust/blob/981346fc07dd5ef414c5b1b21999f7604cece006/compiler/rustc_typeck/src/expr_use_visitor.rs#L28-L38) currently use `PlaceWithHirId` which is composed of Hir `Place` and the
corresponding expression id.

Even though this is an accurate way of expressing how a Place is used,
it can cause confusion during diagnostics.

Eg:

```
let arr : [String; 5];

let [a, ...]     =   arr;
 ^^^ E1 ^^^      =  ^^E2^^
 ```

 Here `arr` is moved because of the binding created E1. However, when we
 point to E1 in diagnostics with the message `arr` was moved, it can be
 confusing.  Rather we would like to report E2 to the user.

 Closes: rust-lang/project-rfc-2229#20

r? `@ghost`

…sakis

Provide diagnostic suggestion in ExprUseVisitor Delegate

The [Delegate trait](https://github.com/rust-lang/rust/blob/981346fc07dd5ef414c5b1b21999f7604cece006/compiler/rustc_typeck/src/expr_use_visitor.rs#L28-L38) currently use `PlaceWithHirId` which is composed of Hir `Place` and the
corresponding expression id.

Even though this is an accurate way of expressing how a Place is used,
it can cause confusion during diagnostics.

Eg:

```
let arr : [String; 5];

let [a, ...]     =   arr;
 ^^^ E1 ^^^      =  ^^E2^^
 ```

 Here `arr` is moved because of the binding created E1. However, when we
 point to E1 in diagnostics with the message `arr` was moved, it can be
 confusing.  Rather we would like to report E2 to the user.

 Closes: rust-lang/project-rfc-2229#20

r? `@ghost`

This was recommended by GitHub Support to try reducing the things that
could've caused #78743. I checked the changelog and there should be no
practical impact for us (we already set an explicit fetch-depth).

Inliner copies the unevaluated constants from the callee body to the
caller at the point where decision to inline is yet to be made. The
constants will be unnecessary if inlining were to fail.

Organize the code moving items from callee to the caller together in one
place to avoid the issue.

Co-authored-by: Joshua Nelson <joshua@yottadb.com>

`crate::` -> `core::`

It looks weird to have `crate::` in the link text and we use the actual
crate name everywhere else.

If anyone is curious, I used this Vim command to update all the links:

    %s/\(\s\)\[`crate::\(.*\)`\]/\1[`core::\2`](crate::\2)/g

'Note however,' -> 'Note, however,'

paramter -> parameter

Bump actions/checkout to version 2

This was recommended by GitHub Support to try reducing the things that could've caused #78743. I checked the changelog and there should be no practical impact for us (we already set an explicit fetch-depth).

r? `@Mark-Simulacrum`

…ntax

Move Vec UI tests to unit tests when possible

Helps with #76268.

I'm moving the tests using `Vec` or `VecDeque`.

````@rustbot```` modify labels: A-testsuite C-cleanup T-libs

Clean up docs for 'as' keyword

Move f64::NAN ui tests into `library`

This is a partial fix of #76268.

r? ```@matklad```

Change as_str → to_string in proc_macro::Ident::span() docs

There is no `as_str` function on Ident any more.

Also change it to an intra doc link while we're at it.

Add keyboard handling to the theme picker menu

This PR is mostly designed to bring the theme picker closer to feature parity with the menu bar from docs.rs. Though the rustdoc theme picker is technically already usable from the keyboard, it's really weird that arrow keys work on some of the menus, but not all of them, in the exact same page.

Array trait impl comment/doc fixes

Two small doc/comment fixes regarding trait implementations on arrays.

(rustdoc) fix test for trait impl display

The test checks that parameters and return values with `impl Trait` types are correctly generated in rustdoc's output.

In essence, the previous version of the test checked the absence of values that would never be generated by rustdoc, so it could basically never fail. These values were adjusted to the expected output and are now required to exist in rustdoc's output. See rust-lang/rust#55201 (comment) for a detailed explanation of the reasoning behind the changes.

Note that the output of rustdoc for `impl Trait`s in parameters and return values did not change since the inital test creation, so this PR only modifies the test.

Closes #55201

fix a couple of clippy warnings:

filter_next
manual_strip
redundant_static_lifetimes
single_char_pattern
unnecessary_cast
unused_unit
op_ref
redundant_closure
useless_conversion