src/tools/clippy/clippy_lints/src/methods/mut_mutex_lock.rs

   1 use clippy_utils::diagnostics::span_lint_and_sugg;
   2 use clippy_utils::{expr_custom_deref_adjustment, ty::is_type_diagnostic_item};
   3 use if_chain::if_chain;
   4 use rustc_errors::Applicability;
   5 use rustc_hir::{Expr, Mutability};
   6 use rustc_lint::LateContext;
   7 use rustc_middle::ty;
   8 use rustc_span::{sym, Span};
   9
  10 use super::MUT_MUTEX_LOCK;
  11
  12 pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, ex: &'tcx Expr<'tcx>, recv: &'tcx Expr<'tcx>, name_span: Span) {
  13     if_chain! {
  14         if matches!(expr_custom_deref_adjustment(cx, recv), None | Some(Mutability::Mut));
  15         if let ty::Ref(_, _, Mutability::Mut) = cx.typeck_results().expr_ty(recv).kind();
  16         if let Some(method_id) = cx.typeck_results().type_dependent_def_id(ex.hir_id);
  17         if let Some(impl_id) = cx.tcx.impl_of_method(method_id);
  18         if is_type_diagnostic_item(cx, cx.tcx.type_of(impl_id), sym::Mutex);
  19         then {
  20             span_lint_and_sugg(
  21                 cx,
  22                 MUT_MUTEX_LOCK,
  23                 name_span,
  24                 "calling `&mut Mutex::lock` unnecessarily locks an exclusive (mutable) reference",
  25                 "change this to",
  26                 "get_mut".to_owned(),
  27                 Applicability::MaybeIncorrect,
  28             );
  29         }
  30     }
  31 }