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https://github.com/rust-lang/rust-clippy
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5fa961b951
Specifically, change `Ty` from this: ``` pub type Ty<'tcx> = &'tcx TyS<'tcx>; ``` to this ``` pub struct Ty<'tcx>(Interned<'tcx, TyS<'tcx>>); ``` There are two benefits to this. - It's now a first class type, so we can define methods on it. This means we can move a lot of methods away from `TyS`, leaving `TyS` as a barely-used type, which is appropriate given that it's not meant to be used directly. - The uniqueness requirement is now explicit, via the `Interned` type. E.g. the pointer-based `Eq` and `Hash` comes from `Interned`, rather than via `TyS`, which wasn't obvious at all. Much of this commit is boring churn. The interesting changes are in these files: - compiler/rustc_middle/src/arena.rs - compiler/rustc_middle/src/mir/visit.rs - compiler/rustc_middle/src/ty/context.rs - compiler/rustc_middle/src/ty/mod.rs Specifically: - Most mentions of `TyS` are removed. It's very much a dumb struct now; `Ty` has all the smarts. - `TyS` now has `crate` visibility instead of `pub`. - `TyS::make_for_test` is removed in favour of the static `BOOL_TY`, which just works better with the new structure. - The `Eq`/`Ord`/`Hash` impls are removed from `TyS`. `Interned`s impls of `Eq`/`Hash` now suffice. `Ord` is now partly on `Interned` (pointer-based, for the `Equal` case) and partly on `TyS` (contents-based, for the other cases). - There are many tedious sigil adjustments, i.e. adding or removing `*` or `&`. They seem to be unavoidable.
70 lines
2.3 KiB
Rust
70 lines
2.3 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::ty::is_type_diagnostic_item;
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use if_chain::if_chain;
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use rustc_errors::Applicability;
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use rustc_hir::{Expr, ExprKind, Mutability};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_middle::ty;
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use rustc_span::sym;
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for `&mut Mutex::lock` calls
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///
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/// ### Why is this bad?
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/// `Mutex::lock` is less efficient than
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/// calling `Mutex::get_mut`. In addition you also have a statically
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/// guarantee that the mutex isn't locked, instead of just a runtime
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/// guarantee.
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///
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/// ### Example
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/// ```rust
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/// use std::sync::{Arc, Mutex};
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///
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/// let mut value_rc = Arc::new(Mutex::new(42_u8));
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/// let value_mutex = Arc::get_mut(&mut value_rc).unwrap();
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///
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/// let mut value = value_mutex.lock().unwrap();
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/// *value += 1;
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/// ```
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/// Use instead:
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/// ```rust
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/// use std::sync::{Arc, Mutex};
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///
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/// let mut value_rc = Arc::new(Mutex::new(42_u8));
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/// let value_mutex = Arc::get_mut(&mut value_rc).unwrap();
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///
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/// let value = value_mutex.get_mut().unwrap();
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/// *value += 1;
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/// ```
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#[clippy::version = "1.49.0"]
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pub MUT_MUTEX_LOCK,
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style,
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"`&mut Mutex::lock` does unnecessary locking"
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}
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declare_lint_pass!(MutMutexLock => [MUT_MUTEX_LOCK]);
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impl<'tcx> LateLintPass<'tcx> for MutMutexLock {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, ex: &'tcx Expr<'tcx>) {
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if_chain! {
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if let ExprKind::MethodCall(path, [self_arg, ..], _) = &ex.kind;
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if path.ident.name == sym!(lock);
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let ty = cx.typeck_results().expr_ty(self_arg);
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if let ty::Ref(_, inner_ty, Mutability::Mut) = ty.kind();
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if is_type_diagnostic_item(cx, *inner_ty, sym::Mutex);
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then {
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span_lint_and_sugg(
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cx,
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MUT_MUTEX_LOCK,
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path.ident.span,
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"calling `&mut Mutex::lock` unnecessarily locks an exclusive (mutable) reference",
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"change this to",
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"get_mut".to_owned(),
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Applicability::MaybeIncorrect,
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);
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}
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}
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}
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}
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