Address review comments

Author: Jules-Bertholet

compiler/rustc_feature/src/unstable.rs

@@ -339,8 +339,6 @@ declare_features! (
     (incomplete, adt_const_params, "1.56.0", Some(95174)),
     /// Allows defining an `#[alloc_error_handler]`.
     (unstable, alloc_error_handler, "1.29.0", Some(51540)),
-    /// Allows `&` and `&mut` patterns to consume match-ergonomics-inserted references.
-    (incomplete, and_pat_everywhere, "CURRENT_RUSTC_VERSION", Some(123076)),
     /// Allows trait methods with arbitrary self types.
     (unstable, arbitrary_self_types, "1.23.0", Some(44874)),
     /// Allows using `const` operands in inline assembly.
@@ -569,6 +567,8 @@ declare_features! (
     (unstable, proc_macro_hygiene, "1.30.0", Some(54727)),
     /// Allows `&raw const $place_expr` and `&raw mut $place_expr` expressions.
     (unstable, raw_ref_op, "1.41.0", Some(64490)),
+    /// Allows `&` and `&mut` patterns to consume match-ergonomics-inserted references.
+    (incomplete, ref_pat_everywhere, "CURRENT_RUSTC_VERSION", Some(123076)),
     /// Allows using the `#[register_tool]` attribute.
     (unstable, register_tool, "1.41.0", Some(66079)),
     /// Allows the `#[repr(i128)]` attribute for enums.

compiler/rustc_hir_typeck/src/pat.rs

@@ -2058,7 +2058,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         mutbl: Mutability,
         expected: Ty<'tcx>,
         pat_info: PatInfo<'tcx, '_>,
-        already_consumed: bool,
+        consumed_inherited_ref: bool,
     ) -> Ty<'tcx> {
         let tcx = self.tcx;
         let expected = self.shallow_resolve(expected);
@@ -2074,13 +2074,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 match *expected.kind() {
                     ty::Ref(_, r_ty, r_mutbl) if r_mutbl == mutbl => (expected, r_ty),
                     _ => {
-                        if already_consumed && self.tcx.features().and_pat_everywhere {
+                        if consumed_inherited_ref && self.tcx.features().ref_pat_everywhere {
                             // We already matched against a match-ergonmics inserted reference,
                             // so we don't need to match against a reference from the original type.
                             // Save this infor for use in lowering later
                             self.typeck_results
                                 .borrow_mut()
-                                .ref_pats_that_dont_deref_mut()
+                                .skipped_ref_pats_mut()
                                 .insert(pat.hir_id);
                             (expected, expected)
                         } else {

compiler/rustc_hir_typeck/src/writeback.rs

@@ -345,7 +345,7 @@ impl<'cx, 'tcx> Visitor<'tcx> for WritebackCx<'cx, 'tcx> {
             _ => {}
         };
 
-        self.visit_ref_pats_that_dont_deref(p.hir_id);
+        self.visit_skipped_ref_pats(p.hir_id);
         self.visit_pat_adjustments(p.span, p.hir_id);
 
         self.visit_node_id(p.span, p.hir_id);
@@ -676,10 +676,10 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
     }
 
     #[instrument(skip(self), level = "debug")]
-    fn visit_ref_pats_that_dont_deref(&mut self, hir_id: hir::HirId) {
-        if self.fcx.typeck_results.borrow_mut().ref_pats_that_dont_deref_mut().remove(hir_id) {
-            debug!("node is a ref pat that doesn't deref");
-            self.typeck_results.ref_pats_that_dont_deref_mut().insert(hir_id);
+    fn visit_skipped_ref_pats(&mut self, hir_id: hir::HirId) {
+        if self.fcx.typeck_results.borrow_mut().skipped_ref_pats_mut().remove(hir_id) {
+            debug!("node is a skipped ref pat");
+            self.typeck_results.skipped_ref_pats_mut().insert(hir_id);
         }
     }
 

compiler/rustc_middle/src/ty/typeck_results.rs

@@ -98,7 +98,7 @@ pub struct TypeckResults<'tcx> {
 
     /// Set of reference patterns that match against a match-ergonomics inserted reference
     /// (as opposed to against a reference in the scrutinee type).
-    ref_pats_that_dont_deref: ItemLocalSet,
+    skipped_ref_pats: ItemLocalSet,
 
     /// Records the reasons that we picked the kind of each closure;
     /// not all closures are present in the map.
@@ -232,7 +232,7 @@ impl<'tcx> TypeckResults<'tcx> {
             adjustments: Default::default(),
             pat_binding_modes: Default::default(),
             pat_adjustments: Default::default(),
-            ref_pats_that_dont_deref: Default::default(),
+            skipped_ref_pats: Default::default(),
             closure_kind_origins: Default::default(),
             liberated_fn_sigs: Default::default(),
             fru_field_types: Default::default(),
@@ -440,12 +440,12 @@ impl<'tcx> TypeckResults<'tcx> {
         LocalTableInContextMut { hir_owner: self.hir_owner, data: &mut self.pat_adjustments }
     }
 
-    pub fn ref_pats_that_dont_deref(&self) -> LocalSetInContext<'_> {
-        LocalSetInContext { hir_owner: self.hir_owner, data: &self.ref_pats_that_dont_deref }
+    pub fn skipped_ref_pats(&self) -> LocalSetInContext<'_> {
+        LocalSetInContext { hir_owner: self.hir_owner, data: &self.skipped_ref_pats }
     }
 
-    pub fn ref_pats_that_dont_deref_mut(&mut self) -> LocalSetInContextMut<'_> {
-        LocalSetInContextMut { hir_owner: self.hir_owner, data: &mut self.ref_pats_that_dont_deref }
+    pub fn skipped_ref_pats_mut(&mut self) -> LocalSetInContextMut<'_> {
+        LocalSetInContextMut { hir_owner: self.hir_owner, data: &mut self.skipped_ref_pats }
     }
 
     /// Does the pattern recursively contain a `ref mut` binding in it?

compiler/rustc_mir_build/src/thir/pattern/mod.rs

@@ -65,16 +65,16 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
         // we wrap the unadjusted pattern in `PatKind::Deref` repeatedly, consuming the
         // adjustments in *reverse order* (last-in-first-out, so that the last `Deref` inserted
         // gets the least-dereferenced type).
-        let unadjusted = if self.typeck_results.ref_pats_that_dont_deref().contains(pat.hir_id) {
-            match pat.kind {
-                hir::PatKind::Ref(inner, _) => self.lower_pattern_unadjusted(inner),
-                _ => span_bug!(pat.span, "non ref pattern marked as non-deref ref pattern"),
+        let unadjusted_pat = match pat.kind {
+            hir::PatKind::Ref(inner, _)
+                if self.typeck_results.skipped_ref_pats().contains(pat.hir_id) =>
+            {
+                self.lower_pattern_unadjusted(inner)
             }
-        } else {
-            self.lower_pattern_unadjusted(pat)
+            _ => self.lower_pattern_unadjusted(pat),
         };
         self.typeck_results.pat_adjustments().get(pat.hir_id).unwrap_or(&vec![]).iter().rev().fold(
-            unadjusted,
+            unadjusted_pat,
             |pat: Box<_>, ref_ty| {
                 debug!("{:?}: wrapping pattern with type {:?}", pat, ref_ty);
                 Box::new(Pat {

compiler/rustc_span/src/symbol.rs

@@ -380,7 +380,6 @@ symbols! {
         alu32,
         always,
         and,
-        and_pat_everywhere,
         and_then,
         anon,
         anon_adt,
@@ -1457,6 +1456,7 @@ symbols! {
         receiver,
         recursion_limit,
         reexport_test_harness_main,
+        ref_pat_everywhere,
         ref_unwind_safe_trait,
         reference,
         reflect,

tests/ui/match/feature-gate-and_pat_everywhere.rs renamed to tests/ui/feature-gates/feature-gate-ref_pat_everywhere.rs

@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/feature-gate-and_pat_everywhere.rs:2:22
+  --> $DIR/feature-gate-ref_pat_everywhere.rs:2:22
    |
 LL |     if let Some(Some(&x)) = &Some(&Some(0)) {
    |                      ^^     --------------- this expression has type `&Option<&Option<{integer}>>`
@@ -14,7 +14,7 @@ LL |     if let Some(Some(x)) = &Some(&Some(0)) {
    |                      ~
 
 error[E0308]: mismatched types
-  --> $DIR/feature-gate-and_pat_everywhere.rs:6:17
+  --> $DIR/feature-gate-ref_pat_everywhere.rs:6:17
    |
 LL |     if let Some(&Some(x)) = &Some(Some(0)) {
    |                 ^^^^^^^^    -------------- this expression has type `&Option<Option<{integer}>>`
@@ -25,7 +25,7 @@ LL |     if let Some(&Some(x)) = &Some(Some(0)) {
            found reference `&_`
 
 error[E0308]: mismatched types
-  --> $DIR/feature-gate-and_pat_everywhere.rs:10:22
+  --> $DIR/feature-gate-ref_pat_everywhere.rs:10:22
    |
 LL |     if let Some(Some(&mut x)) = &mut Some(&mut Some(0)) {
    |                      ^^^^^^     ----------------------- this expression has type `&mut Option<&mut Option<{integer}>>`
@@ -35,7 +35,7 @@ LL |     if let Some(Some(&mut x)) = &mut Some(&mut Some(0)) {
    = note:           expected type `{integer}`
            found mutable reference `&mut _`
 note: to declare a mutable binding use: `mut x`
-  --> $DIR/feature-gate-and_pat_everywhere.rs:10:22
+  --> $DIR/feature-gate-ref_pat_everywhere.rs:10:22
    |
 LL |     if let Some(Some(&mut x)) = &mut Some(&mut Some(0)) {
    |                      ^^^^^^

tests/ui/match/feature-gate-and_pat_everywhere.stderr renamed to tests/ui/feature-gates/feature-gate-ref_pat_everywhere.stderr

@@ -1,5 +1,5 @@
 #![allow(incomplete_features)]
-#![feature(and_pat_everywhere)]
+#![feature(ref_pat_everywhere)]
 pub fn main() {
     if let Some(&x) = Some(0) {
         //~^ ERROR: mismatched types [E0308]
@@ -9,4 +9,8 @@ pub fn main() {
         //~^ ERROR: mismatched types [E0308]
         let _: u32 = x;
     }
+    if let Some(&x) = &mut Some(0) {
+        //~^ ERROR: mismatched types [E0308]
+        let _: u32 = x;
+    }
 }

tests/ui/match/and_pat_everywhere-mutability-mismatch.rs renamed to tests/ui/match/ref_pat_everywhere-mutability-mismatch.rs

@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/and_pat_everywhere-mutability-mismatch.rs:4:17
+  --> $DIR/ref_pat_everywhere-mutability-mismatch.rs:4:17
    |
 LL |     if let Some(&x) = Some(0) {
    |                 ^^    ------- this expression has type `Option<{integer}>`
@@ -14,7 +14,7 @@ LL |     if let Some(x) = Some(0) {
    |                 ~
 
 error[E0308]: mismatched types
-  --> $DIR/and_pat_everywhere-mutability-mismatch.rs:8:12
+  --> $DIR/ref_pat_everywhere-mutability-mismatch.rs:8:12
    |
 LL |     if let &Some(x) = &mut Some(0) {
    |            ^^^^^^^^   ------------ this expression has type `&mut Option<{integer}>`
@@ -24,6 +24,21 @@ LL |     if let &Some(x) = &mut Some(0) {
    = note: expected mutable reference `&mut Option<{integer}>`
                       found reference `&_`
 
-error: aborting due to 2 previous errors
+error[E0308]: mismatched types
+  --> $DIR/ref_pat_everywhere-mutability-mismatch.rs:12:17
+   |
+LL |     if let Some(&x) = &mut Some(0) {
+   |                 ^^    ------------ this expression has type `&mut Option<{integer}>`
+   |                 |
+   |                 expected integer, found `&_`
+   |
+   = note:   expected type `{integer}`
+           found reference `&_`
+help: consider removing `&` from the pattern
+   |
+LL |     if let Some(x) = &mut Some(0) {
+   |                 ~
+
+error: aborting due to 3 previous errors
 
 For more information about this error, try `rustc --explain E0308`.