Implement mut ref/mut ref mut

Author: Jules-Bertholet

clippy_lints/src/functions/misnamed_getters.rs

@@ -24,13 +24,13 @@ pub fn check_fn(cx: &LateContext<'_>, kind: FnKind<'_>, decl: &FnDecl<'_>, body:
     let name = ident.name.as_str();
 
     let name = match decl.implicit_self {
-        ImplicitSelfKind::MutRef => {
+        ImplicitSelfKind::RefMut => {
             let Some(name) = name.strip_suffix("_mut") else {
                 return;
             };
             name
         },
-        ImplicitSelfKind::Imm | ImplicitSelfKind::Mut | ImplicitSelfKind::ImmRef => name,
+        ImplicitSelfKind::Imm | ImplicitSelfKind::Mut | ImplicitSelfKind::RefImm => name,
         ImplicitSelfKind::None => return,
     };
 

clippy_lints/src/index_refutable_slice.rs

@@ -97,7 +97,7 @@ fn find_slice_values(cx: &LateContext<'_>, pat: &hir::Pat<'_>) -> FxIndexMap<hir
             value_hir_id,
             ident,
             sub_pat,
-        ) = pat.kind
+        ) = pat.kind && by_ref != hir::ByRef::Yes(hir::Mutability::Mut)
         {
             // This block catches bindings with sub patterns. It would be hard to build a correct suggestion
             // for them and it's likely that the user knows what they are doing in such a case.
@@ -115,7 +115,7 @@ fn find_slice_values(cx: &LateContext<'_>, pat: &hir::Pat<'_>) -> FxIndexMap<hir
             if let ty::Slice(inner_ty) | ty::Array(inner_ty, _) = bound_ty.peel_refs().kind() {
                 // The values need to use the `ref` keyword if they can't be copied.
                 // This will need to be adjusted if the lint want to support mutable access in the future
-                let src_is_ref = bound_ty.is_ref() && by_ref != hir::ByRef::Yes;
+                let src_is_ref = bound_ty.is_ref() && by_ref == hir::ByRef::No;
                 let needs_ref = !(src_is_ref || is_copy(cx, *inner_ty));
 
                 let slice_info = slices

clippy_lints/src/iter_without_into_iter.rs

@@ -216,8 +216,8 @@ impl {self_ty_without_ref} {{
     fn check_impl_item(&mut self, cx: &LateContext<'_>, item: &rustc_hir::ImplItem<'_>) {
         let item_did = item.owner_id.to_def_id();
         let (borrow_prefix, expected_implicit_self) = match item.ident.name {
-            sym::iter => ("&", ImplicitSelfKind::ImmRef),
-            sym::iter_mut => ("&mut ", ImplicitSelfKind::MutRef),
+            sym::iter => ("&", ImplicitSelfKind::RefImm),
+            sym::iter_mut => ("&mut ", ImplicitSelfKind::RefMut),
             _ => return,
         };
 

clippy_lints/src/len_zero.rs

@@ -384,8 +384,8 @@ impl LenOutput {
 
     fn expected_sig(self, self_kind: ImplicitSelfKind) -> String {
         let self_ref = match self_kind {
-            ImplicitSelfKind::ImmRef => "&",
-            ImplicitSelfKind::MutRef => "&mut ",
+            ImplicitSelfKind::RefImm => "&",
+            ImplicitSelfKind::RefMut => "&mut ",
             _ => "",
         };
         match self {
@@ -411,8 +411,8 @@ fn check_is_empty_sig<'tcx>(
         [arg, res] if len_output.matches_is_empty_output(cx, *res) => {
             matches!(
                 (arg.kind(), self_kind),
-                (ty::Ref(_, _, Mutability::Not), ImplicitSelfKind::ImmRef)
-                    | (ty::Ref(_, _, Mutability::Mut), ImplicitSelfKind::MutRef)
+                (ty::Ref(_, _, Mutability::Not), ImplicitSelfKind::RefImm)
+                    | (ty::Ref(_, _, Mutability::Mut), ImplicitSelfKind::RefMut)
             ) || (!arg.is_ref() && matches!(self_kind, ImplicitSelfKind::Imm | ImplicitSelfKind::Mut))
         },
         _ => false,

clippy_lints/src/matches/infallible_destructuring_match.rs

@@ -2,7 +2,7 @@ use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::snippet_with_applicability;
 use clippy_utils::{path_to_local_id, peel_blocks, strip_pat_refs};
 use rustc_errors::Applicability;
-use rustc_hir::{ByRef, ExprKind, LetStmt, MatchSource, PatKind, QPath};
+use rustc_hir::{ExprKind, LetStmt, MatchSource, PatKind, QPath};
 use rustc_lint::LateContext;
 
 use super::INFALLIBLE_DESTRUCTURING_MATCH;
@@ -30,7 +30,7 @@ pub(crate) fn check(cx: &LateContext<'_>, local: &LetStmt<'_>) -> bool {
             format!(
                 "let {}({}{}) = {};",
                 snippet_with_applicability(cx, variant_name.span, "..", &mut applicability),
-                if binding.0 == ByRef::Yes { "ref " } else { "" },
+                binding.prefix_str(),
                 snippet_with_applicability(cx, local.pat.span, "..", &mut applicability),
                 snippet_with_applicability(cx, target.span, "..", &mut applicability),
             ),

clippy_lints/src/matches/match_as_ref.rs

@@ -67,7 +67,7 @@ fn is_none_arm(cx: &LateContext<'_>, arm: &Arm<'_>) -> bool {
 fn is_ref_some_arm(cx: &LateContext<'_>, arm: &Arm<'_>) -> Option<Mutability> {
     if let PatKind::TupleStruct(ref qpath, [first_pat, ..], _) = arm.pat.kind
         && is_res_lang_ctor(cx, cx.qpath_res(qpath, arm.pat.hir_id), LangItem::OptionSome)
-        && let PatKind::Binding(BindingAnnotation(ByRef::Yes, mutabl), .., ident, _) = first_pat.kind
+        && let PatKind::Binding(BindingAnnotation(ByRef::Yes(mutabl), _), .., ident, _) = first_pat.kind
         && let ExprKind::Call(e, [arg]) = peel_blocks(arm.body).kind
         && is_res_lang_ctor(cx, path_res(cx, e), LangItem::OptionSome)
         && let ExprKind::Path(QPath::Resolved(_, path2)) = arg.kind

clippy_lints/src/matches/needless_match.rs

@@ -178,7 +178,7 @@ fn pat_same_as_expr(pat: &Pat<'_>, expr: &Expr<'_>) -> bool {
                 },
             )),
         ) => {
-            return !matches!(annot, BindingAnnotation(ByRef::Yes, _)) && pat_ident.name == first_seg.ident.name;
+            return !matches!(annot, BindingAnnotation(ByRef::Yes(_), _)) && pat_ident.name == first_seg.ident.name;
         },
         // Example: `Custom::TypeA => Custom::TypeB`, or `None => None`
         (PatKind::Path(QPath::Resolved(_, p_path)), ExprKind::Path(QPath::Resolved(_, e_path))) => {

clippy_lints/src/matches/redundant_guards.rs

@@ -182,7 +182,7 @@ fn get_pat_binding<'tcx>(
             if let PatKind::Binding(bind_annot, hir_id, ident, _) = pat.kind
                 && hir_id == local
             {
-                if matches!(bind_annot.0, rustc_ast::ByRef::Yes) {
+                if matches!(bind_annot.0, rustc_ast::ByRef::Yes(_)) {
                     let _ = byref_ident.insert(ident);
                 }
                 // the second call of `replace()` returns a `Some(span)`, meaning a multi-binding pattern

clippy_lints/src/methods/clone_on_copy.rs

@@ -69,7 +69,7 @@ pub(super) fn check(
                 _ => false,
             },
             // local binding capturing a reference
-            Node::LetStmt(l) if matches!(l.pat.kind, PatKind::Binding(BindingAnnotation(ByRef::Yes, _), ..)) => {
+            Node::LetStmt(l) if matches!(l.pat.kind, PatKind::Binding(BindingAnnotation(ByRef::Yes(_), _), ..)) => {
                 return;
             },
             _ => false,

clippy_lints/src/methods/iter_kv_map.rs

@@ -60,16 +60,15 @@ pub(super) fn check<'tcx>(
                 applicability,
             );
         } else {
-            let ref_annotation = if annotation.0 == ByRef::Yes { "ref " } else { "" };
-            let mut_annotation = if annotation.1 == Mutability::Mut { "mut " } else { "" };
             span_lint_and_sugg(
                 cx,
                 ITER_KV_MAP,
                 expr.span,
                 &format!("iterating on a map's {replacement_kind}s"),
                 "try",
                 format!(
-                    "{recv_snippet}.{into_prefix}{replacement_kind}s().map(|{ref_annotation}{mut_annotation}{bound_ident}| {})",
+                    "{recv_snippet}.{into_prefix}{replacement_kind}s().map(|{}{bound_ident}| {})",
+                    annotation.prefix_str(),
                     snippet_with_applicability(cx, body_expr.span, "/* body */", &mut applicability)
                 ),
                 applicability,

clippy_lints/src/misc.rs

@@ -129,7 +129,7 @@ impl<'tcx> LateLintPass<'tcx> for LintPass {
             if !is_lint_allowed(cx, REF_PATTERNS, arg.pat.hir_id) {
                 return;
             }
-            if let PatKind::Binding(BindingAnnotation(ByRef::Yes, _), ..) = arg.pat.kind {
+            if let PatKind::Binding(BindingAnnotation(ByRef::Yes(_), _), ..) = arg.pat.kind {
                 span_lint(
                     cx,
                     TOPLEVEL_REF_ARG,
@@ -144,7 +144,7 @@ impl<'tcx> LateLintPass<'tcx> for LintPass {
     fn check_stmt(&mut self, cx: &LateContext<'tcx>, stmt: &'tcx Stmt<'_>) {
         if !in_external_macro(cx.tcx.sess, stmt.span)
             && let StmtKind::Let(local) = stmt.kind
-            && let PatKind::Binding(BindingAnnotation(ByRef::Yes, mutabl), .., name, None) = local.pat.kind
+            && let PatKind::Binding(BindingAnnotation(ByRef::Yes(mutabl), _), .., name, None) = local.pat.kind
             && let Some(init) = local.init
             // Do not emit if clippy::ref_patterns is not allowed to avoid having two lints for the same issue.
             && is_lint_allowed(cx, REF_PATTERNS, local.pat.hir_id)

clippy_lints/src/question_mark.rs

@@ -14,7 +14,7 @@ use rustc_errors::Applicability;
 use rustc_hir::def::Res;
 use rustc_hir::LangItem::{self, OptionNone, OptionSome, ResultErr, ResultOk};
 use rustc_hir::{
-    BindingAnnotation, Block, ByRef, Expr, ExprKind, LetStmt, Node, PatKind, PathSegment, QPath, Stmt, StmtKind,
+    BindingAnnotation, Block, ByRef, Expr, ExprKind, LetStmt, Mutability, Node, PatKind, PathSegment, QPath, Stmt, StmtKind,
 };
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty::Ty;
@@ -283,9 +283,13 @@ fn check_if_let_some_or_err_and_early_return<'tcx>(cx: &LateContext<'tcx>, expr:
         let mut applicability = Applicability::MachineApplicable;
         let receiver_str = snippet_with_applicability(cx, let_expr.span, "..", &mut applicability);
         let requires_semi = matches!(cx.tcx.parent_hir_node(expr.hir_id), Node::Stmt(_));
+        let method_call_str = match by_ref {
+            ByRef::Yes(Mutability::Mut) => ".as_mut()",
+            ByRef::Yes(Mutability::Not) => ".as_ref()",
+            ByRef::No => "",
+        };
         let sugg = format!(
-            "{receiver_str}{}?{}",
-            if by_ref == ByRef::Yes { ".as_ref()" } else { "" },
+            "{receiver_str}{method_call_str}?{}",
             if requires_semi { ";" } else { "" }
         );
         span_lint_and_sugg(

clippy_lints/src/utils/author.rs

@@ -649,6 +649,8 @@ impl<'a, 'tcx> PrintVisitor<'a, 'tcx> {
                     BindingAnnotation::REF => "REF",
                     BindingAnnotation::MUT => "MUT",
                     BindingAnnotation::REF_MUT => "REF_MUT",
+                    BindingAnnotation::MUT_REF => "MUT_REF",
+                    BindingAnnotation::MUT_REF_MUT => "MUT_REF_MUT",
                 };
                 kind!("Binding(BindingAnnotation::{ann}, _, {name}, {sub})");
                 self.ident(name);

clippy_utils/src/lib.rs

@@ -97,7 +97,7 @@ use rustc_hir::hir_id::{HirIdMap, HirIdSet};
 use rustc_hir::intravisit::{walk_expr, FnKind, Visitor};
 use rustc_hir::LangItem::{OptionNone, OptionSome, ResultErr, ResultOk};
 use rustc_hir::{
-    self as hir, def, Arm, ArrayLen, BindingAnnotation, Block, BlockCheckMode, Body, Closure, Destination, Expr,
+    self as hir, def, Arm, ArrayLen, BindingAnnotation, Block, BlockCheckMode, Body, ByRef, Closure, Destination, Expr,
     ExprField, ExprKind, FnDecl, FnRetTy, GenericArgs, HirId, Impl, ImplItem, ImplItemKind, ImplItemRef, Item,
     ItemKind, LangItem, LetStmt, MatchSource, Mutability, Node, OwnerId, Param, Pat, PatKind, Path, PathSegment, PrimTy,
     QPath, Stmt, StmtKind, TraitItem, TraitItemKind, TraitItemRef, TraitRef, TyKind, UnOp,
@@ -107,7 +107,6 @@ use rustc_lint::{LateContext, Level, Lint, LintContext};
 use rustc_middle::hir::place::PlaceBase;
 use rustc_middle::mir::Const;
 use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow};
-use rustc_middle::ty::binding::BindingMode;
 use rustc_middle::ty::fast_reject::SimplifiedType;
 use rustc_middle::ty::layout::IntegerExt;
 use rustc_middle::ty::{
@@ -1006,11 +1005,12 @@ pub fn capture_local_usage(cx: &LateContext<'_>, e: &Expr<'_>) -> CaptureKind {
             .typeck_results()
             .extract_binding_mode(cx.sess(), id, span)
             .unwrap()
+            .0
         {
-            BindingMode::BindByValue(_) if !is_copy(cx, cx.typeck_results().node_type(id)) => {
+            ByRef::No if !is_copy(cx, cx.typeck_results().node_type(id)) => {
                 capture = CaptureKind::Value;
             },
-            BindingMode::BindByReference(Mutability::Mut) if capture != CaptureKind::Value => {
+            ByRef::Yes(Mutability::Mut) if capture != CaptureKind::Value => {
                 capture = CaptureKind::Ref(Mutability::Mut);
             },
             _ => (),
@@ -2035,7 +2035,7 @@ fn is_body_identity_function(cx: &LateContext<'_>, func: &Body<'_>) -> bool {
             .typeck_results()
             .pat_binding_modes()
             .get(pat.hir_id)
-            .is_some_and(|mode| matches!(mode, BindingMode::BindByReference(_)))
+            .is_some_and(|mode| matches!(mode.0, ByRef::Yes(_)))
         {
             // If a tuple `(x, y)` is of type `&(i32, i32)`, then due to match ergonomics,
             // the inner patterns become references. Don't consider this the identity function