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r? @Manishearth

A few days delayed, because I recovered from a cold last week and couldn't get myself to do the sync, sorry. 🙃

CrazyRoka and others added 30 commits December 16, 2021 18:57
by using a static data structure to track transitive relations.
- fix code that have variables that is "only used in recursion"
- add test
…rsion

# Conflicts:
#	clippy_lints/src/lib.rs
…-in macros

Previously it always returned `MacroKind::Bang` while some of those macros are actually attributes and derives
…error-span, r=jackh726

better ObligationCause for normalization errors in `can_type_implement_copy`

Some logic is needed so we can point to the field when given totally nonsense types like `struct Foo(<u32 as Iterator>::Item);`

Fixes rust-lang#93687
rustc_errors: let `DiagnosticBuilder::emit` return a "guarantee of emission".

That is, `DiagnosticBuilder` is now generic over the return type of `.emit()`, so we'll now have:
* `DiagnosticBuilder<ErrorReported>` for error (incl. fatal/bug) diagnostics
  * can only be created via a `const L: Level`-generic constructor, that limits allowed variants via a `where` clause, so not even `rustc_errors` can accidentally bypass this limitation
  * asserts `diagnostic.is_error()` on emission, just in case the construction restriction was bypassed (e.g. by replacing the whole `Diagnostic` inside `DiagnosticBuilder`)
  * `.emit()` returns `ErrorReported`, as a "proof" token that `.emit()` was called
    (though note that this isn't a real guarantee until after completing the work on
     rust-lang#69426)
* `DiagnosticBuilder<()>` for everything else (warnings, notes, etc.)
  * can also be obtained from other `DiagnosticBuilder`s by calling `.forget_guarantee()`

This PR is a companion to other ongoing work, namely:
* rust-lang#69426
  and it's ongoing implementation:
  rust-lang#93222
  the API changes in this PR are needed to get statically-checked "only errors produce `ErrorReported` from `.emit()`", but doesn't itself provide any really strong guarantees without those other `ErrorReported` changes
* rust-lang#93244
  would make the choices of API changes (esp. naming) in this PR fit better overall

In order to be able to let `.emit()` return anything trustable, several changes had to be made:
* `Diagnostic`'s `level` field is now private to `rustc_errors`, to disallow arbitrary "downgrade"s from "some kind of error" to "warning" (or anything else that doesn't cause compilation to fail)
  * it's still possible to replace the whole `Diagnostic` inside the `DiagnosticBuilder`, sadly, that's harder to fix, but it's unlikely enough that we can paper over it with asserts on `.emit()`
* `.cancel()` now consumes `DiagnosticBuilder`, preventing `.emit()` calls on a cancelled diagnostic
  * it's also now done internally, through `DiagnosticBuilder`-private state, instead of having a `Level::Cancelled` variant that can be read (or worse, written) by the user
  * this removes a hazard of calling `.cancel()` on an error then continuing to attach details to it, and even expect to be able to `.emit()` it
  * warnings were switched to *only* `can_emit_warnings` on emission (instead of pre-cancelling early)
  * `struct_dummy` was removed (as it relied on a pre-`Cancelled` `Diagnostic`)
* since `.emit()` doesn't consume the `DiagnosticBuilder` <sub>(I tried and gave up, it's much more work than this PR)</sub>,
  we have to make `.emit()` idempotent wrt the guarantees it returns
  * thankfully, `err.emit(); err.emit();` can return `ErrorReported` both times, as the second `.emit()` call has no side-effects *only* because the first one did do the appropriate emission
* `&mut Diagnostic` is now used in a lot of function signatures, which used to take `&mut DiagnosticBuilder` (in the interest of not having to make those functions generic)
  * the APIs were already mostly identical, allowing for low-effort porting to this new setup
  * only some of the suggestion methods needed some rework, to have the extra `DiagnosticBuilder` functionality on the `Diagnostic` methods themselves (that change is also present in rust-lang#93259)
  * `.emit()`/`.cancel()` aren't available, but IMO calling them from an "error decorator/annotator" function isn't a good practice, and can lead to strange behavior (from the caller's perspective)
  * `.downgrade_to_delayed_bug()` was added, letting you convert any `.is_error()` diagnostic into a `delay_span_bug` one (which works because in both cases the guarantees available are the same)

This PR should ideally be reviewed commit-by-commit, since there is a lot of fallout in each.

r? `@estebank` cc `@Manishearth` `@nikomatsakis` `@mark-i-m`
J-ZhengLi and others added 15 commits March 10, 2022 09:44
and change its lint group to "complexity"
…les, r=camsteffen

Improve styles of filtering options for Clippy's lint list

Partially solves rust-lang#7958

Updated styles for filtering options. It now uses dropdown menus.

![image](https://user-images.githubusercontent.com/19844144/144608479-cdd9de0b-f101-4d49-a135-0969efb01a11.png)

changelog: none
This commit makes `AdtDef` use `Interned`. Much the commit is tedious
changes to introduce getter functions. The interesting changes are in
`compiler/rustc_middle/src/ty/adt.rs`.
new lint that detects useless match expression

fixes rust-lang#7040

changelog: Add new  lint [`needless_match`] under complexity lint group
…logiq

new lint: `only_used_in_recursion`

changed:
- added `only_used_in_recursion`.
- fixed code that variables are only used in recursion.
- this would not lint when `unused_variable`

This fixes: rust-lang#8390

-----

changelog: add lint [`only_used_in_recursion`]
Rustup

r? `@ghost`

changelog: none
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Some changes occurred in src/tools/clippy.

cc @rust-lang/clippy

@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Mar 14, 2022
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@bors r+ p=2 rollup=never

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bors commented Mar 14, 2022

📌 Commit 706fa54 has been approved by Manishearth

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Mar 14, 2022
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bors commented Mar 14, 2022

⌛ Testing commit 706fa54 with merge 285fa7e...

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bors commented Mar 14, 2022

☀️ Test successful - checks-actions
Approved by: Manishearth
Pushing 285fa7e to master...

@bors bors added the merged-by-bors This PR was explicitly merged by bors. label Mar 14, 2022
@bors bors merged commit 285fa7e into rust-lang:master Mar 14, 2022
@rustbot rustbot added this to the 1.61.0 milestone Mar 14, 2022
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Finished benchmarking commit (285fa7e): comparison url.

Summary: This benchmark run did not return any relevant results.

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

@rustbot label: -perf-regression

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