use rustc_hir as hir;
use rustc_hir::intravisit;
use rustc_lint::{LateContext, LateLintPass, LintContext};
-use rustc_middle::hir::map::Map;
use rustc_middle::lint::in_external_macro;
use rustc_middle::ty;
use rustc_session::{declare_lint_pass, declare_tool_lint};
declare_clippy_lint! {
- /// **What it does:** Checks for instances of `mut mut` references.
+ /// ### What it does
+ /// Checks for instances of `mut mut` references.
///
- /// **Why is this bad?** Multiple `mut`s don't add anything meaningful to the
+ /// ### Why is this bad?
+ /// Multiple `mut`s don't add anything meaningful to the
/// source. This is either a copy'n'paste error, or it shows a fundamental
/// misunderstanding of references.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// # let mut y = 1;
/// let x = &mut &mut y;
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub MUT_MUT,
pedantic,
"usage of double-mut refs, e.g., `&mut &mut ...`"
}
impl<'a, 'tcx> intravisit::Visitor<'tcx> for MutVisitor<'a, 'tcx> {
- type Map = Map<'tcx>;
-
fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
if in_external_macro(self.cx.sess(), expr.span) {
return;
}
- if let Some((_, arg, body, _)) = higher::for_loop(expr) {
+ if let Some(higher::ForLoop { arg, body, .. }) = higher::ForLoop::hir(expr) {
// A `for` loop lowers to:
// ```rust
// match ::std::iter::Iterator::next(&mut iter) {
expr.span,
"generally you want to avoid `&mut &mut _` if possible",
);
- } else if let ty::Ref(_, _, hir::Mutability::Mut) = self.cx.typeck_results().expr_ty(e).kind() {
- span_lint(
- self.cx,
- MUT_MUT,
- expr.span,
- "this expression mutably borrows a mutable reference. Consider reborrowing",
- );
+ } else if let ty::Ref(_, ty, hir::Mutability::Mut) = self.cx.typeck_results().expr_ty(e).kind() {
+ if ty.peel_refs().is_sized(self.cx.tcx, self.cx.param_env) {
+ span_lint(
+ self.cx,
+ MUT_MUT,
+ expr.span,
+ "this expression mutably borrows a mutable reference. Consider reborrowing",
+ );
+ }
}
}
}
fn visit_ty(&mut self, ty: &'tcx hir::Ty<'_>) {
+ if in_external_macro(self.cx.sess(), ty.span) {
+ return;
+ }
+
if let hir::TyKind::Rptr(
_,
hir::MutTy {
intravisit::walk_ty(self, ty);
}
- fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
- intravisit::NestedVisitorMap::None
- }
}