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

   1 use clippy_utils::diagnostics::span_lint_and_sugg;
   2 use clippy_utils::path_res;
   3 use clippy_utils::source::snippet_opt;
   4 use clippy_utils::ty::is_type_diagnostic_item;
   5 use clippy_utils::usage::local_used_after_expr;
   6 use rustc_errors::Applicability;
   7 use rustc_hir::def::Res;
   8 use rustc_hir::Expr;
   9 use rustc_lint::LateContext;
  10 use rustc_span::sym;
  11
  12 use super::NEEDLESS_OPTION_AS_DEREF;
  13
  14 pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, recv: &Expr<'_>, name: &str) {
  15     let typeck = cx.typeck_results();
  16     let outer_ty = typeck.expr_ty(expr);
  17
  18     if is_type_diagnostic_item(cx, outer_ty, sym::Option) && outer_ty == typeck.expr_ty(recv) {
  19         if name == "as_deref_mut" && recv.is_syntactic_place_expr() {
  20             let Res::Local(binding_id) = path_res(cx, recv) else { return };
  21
  22             if local_used_after_expr(cx, binding_id, recv) {
  23                 return;
  24             }
  25         }
  26
  27         span_lint_and_sugg(
  28             cx,
  29             NEEDLESS_OPTION_AS_DEREF,
  30             expr.span,
  31             "derefed type is same as origin",
  32             "try this",
  33             snippet_opt(cx, recv.span).unwrap(),
  34             Applicability::MachineApplicable,
  35         );
  36     }
  37 }