Auto merge of #87140 - camsteffen:pat-slice-refs, r=oli-obk

Remove refs from Pat slices

Changes `PatKind::Or(&'hir [&'hir Pat<'hir>])` to `PatKind::Or(&'hir [Pat<'hir>])` and others. This is more consistent with `ExprKind`, saves a little memory, and is a little easier to use.

Author: bors

Diff for: compiler/rustc_ast_lowering/src/expr.rs

@@ -1067,6 +1067,15 @@ impl<'hir> LoweringContext<'_, 'hir> {
         eq_sign_span: Span,
         assignments: &mut Vec<hir::Stmt<'hir>>,
     ) -> &'hir hir::Pat<'hir> {
+        self.arena.alloc(self.destructure_assign_mut(lhs, eq_sign_span, assignments))
+    }
+
+    fn destructure_assign_mut(
+        &mut self,
+        lhs: &Expr,
+        eq_sign_span: Span,
+        assignments: &mut Vec<hir::Stmt<'hir>>,
+    ) -> hir::Pat<'hir> {
         match &lhs.kind {
             // Underscore pattern.
             ExprKind::Underscore => {
@@ -1080,7 +1089,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     let (before, after) = pats.split_at(i);
                     hir::PatKind::Slice(
                         before,
-                        Some(self.pat_without_dbm(span, hir::PatKind::Wild)),
+                        Some(self.arena.alloc(self.pat_without_dbm(span, hir::PatKind::Wild))),
                         after,
                     )
                 } else {
@@ -1165,14 +1174,14 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     let tuple_pat = hir::PatKind::Tuple(&[], Some(0));
                     return self.pat_without_dbm(lhs.span, tuple_pat);
                 } else {
-                    return self.destructure_assign(e, eq_sign_span, assignments);
+                    return self.destructure_assign_mut(e, eq_sign_span, assignments);
                 }
             }
             _ => {}
         }
         // Treat all other cases as normal lvalue.
         let ident = Ident::new(sym::lhs, lhs.span);
-        let (pat, binding) = self.pat_ident(lhs.span, ident);
+        let (pat, binding) = self.pat_ident_mut(lhs.span, ident);
         let ident = self.expr_ident(lhs.span, ident, binding);
         let assign = hir::ExprKind::Assign(self.lower_expr(lhs), ident, eq_sign_span);
         let expr = self.expr(lhs.span, assign, ThinVec::new());
@@ -1191,7 +1200,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         ctx: &str,
         eq_sign_span: Span,
         assignments: &mut Vec<hir::Stmt<'hir>>,
-    ) -> (&'hir [&'hir hir::Pat<'hir>], Option<(usize, Span)>) {
+    ) -> (&'hir [hir::Pat<'hir>], Option<(usize, Span)>) {
         let mut rest = None;
         let elements =
             self.arena.alloc_from_iter(elements.iter().enumerate().filter_map(|(i, e)| {
@@ -1204,7 +1213,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     }
                     None
                 } else {
-                    Some(self.destructure_assign(e, eq_sign_span, assignments))
+                    Some(self.destructure_assign_mut(e, eq_sign_span, assignments))
                 }
             }));
         (elements, rest)

Diff for: compiler/rustc_ast_lowering/src/lib.rs

@@ -2577,21 +2577,35 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         self.pat_ident_binding_mode(span, ident, hir::BindingAnnotation::Unannotated)
     }
 
+    fn pat_ident_mut(&mut self, span: Span, ident: Ident) -> (hir::Pat<'hir>, hir::HirId) {
+        self.pat_ident_binding_mode_mut(span, ident, hir::BindingAnnotation::Unannotated)
+    }
+
     fn pat_ident_binding_mode(
         &mut self,
         span: Span,
         ident: Ident,
         bm: hir::BindingAnnotation,
     ) -> (&'hir hir::Pat<'hir>, hir::HirId) {
+        let (pat, hir_id) = self.pat_ident_binding_mode_mut(span, ident, bm);
+        (self.arena.alloc(pat), hir_id)
+    }
+
+    fn pat_ident_binding_mode_mut(
+        &mut self,
+        span: Span,
+        ident: Ident,
+        bm: hir::BindingAnnotation,
+    ) -> (hir::Pat<'hir>, hir::HirId) {
         let hir_id = self.next_id();
 
         (
-            self.arena.alloc(hir::Pat {
+            hir::Pat {
                 hir_id,
                 kind: hir::PatKind::Binding(bm, hir_id, ident.with_span_pos(span), None),
                 span,
                 default_binding_modes: true,
-            }),
+            },
             hir_id,
         )
     }
@@ -2609,13 +2623,8 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         })
     }
 
-    fn pat_without_dbm(&mut self, span: Span, kind: hir::PatKind<'hir>) -> &'hir hir::Pat<'hir> {
-        self.arena.alloc(hir::Pat {
-            hir_id: self.next_id(),
-            kind,
-            span,
-            default_binding_modes: false,
-        })
+    fn pat_without_dbm(&mut self, span: Span, kind: hir::PatKind<'hir>) -> hir::Pat<'hir> {
+        hir::Pat { hir_id: self.next_id(), kind, span, default_binding_modes: false }
     }
 
     fn ty_path(

Diff for: compiler/rustc_ast_lowering/src/pat.rs

@@ -10,7 +10,11 @@ use rustc_span::symbol::Ident;
 use rustc_span::{source_map::Spanned, Span};
 
 impl<'a, 'hir> LoweringContext<'a, 'hir> {
-    crate fn lower_pat(&mut self, mut pattern: &Pat) -> &'hir hir::Pat<'hir> {
+    crate fn lower_pat(&mut self, pattern: &Pat) -> &'hir hir::Pat<'hir> {
+        self.arena.alloc(self.lower_pat_mut(pattern))
+    }
+
+    crate fn lower_pat_mut(&mut self, mut pattern: &Pat) -> hir::Pat<'hir> {
         ensure_sufficient_stack(|| {
             // loop here to avoid recursion
             let node = loop {
@@ -34,7 +38,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     }
                     PatKind::Or(ref pats) => {
                         break hir::PatKind::Or(
-                            self.arena.alloc_from_iter(pats.iter().map(|x| self.lower_pat(x))),
+                            self.arena.alloc_from_iter(pats.iter().map(|x| self.lower_pat_mut(x))),
                         );
                     }
                     PatKind::Path(ref qself, ref path) => {
@@ -101,7 +105,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         &mut self,
         pats: &[P<Pat>],
         ctx: &str,
-    ) -> (&'hir [&'hir hir::Pat<'hir>], Option<usize>) {
+    ) -> (&'hir [hir::Pat<'hir>], Option<usize>) {
         let mut elems = Vec::with_capacity(pats.len());
         let mut rest = None;
 
@@ -140,7 +144,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             }
 
             // It was not a sub-tuple pattern so lower it normally.
-            elems.push(self.lower_pat(pat));
+            elems.push(self.lower_pat_mut(pat));
         }
 
         for (_, pat) in iter {
@@ -149,7 +153,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 // ...but there was one again, so error.
                 self.ban_extra_rest_pat(pat.span, rest.unwrap().1, ctx);
             } else {
-                elems.push(self.lower_pat(pat));
+                elems.push(self.lower_pat_mut(pat));
             }
         }
 
@@ -189,11 +193,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 // Record, lower it to `$binding_mode $ident @ _`, and stop here.
                 PatKind::Ident(ref bm, ident, Some(ref sub)) if sub.is_rest() => {
                     prev_rest_span = Some(sub.span);
-                    slice = Some(lower_rest_sub(self, pat, bm, ident, sub));
+                    slice = Some(self.arena.alloc(lower_rest_sub(self, pat, bm, ident, sub)));
                     break;
                 }
                 // It was not a subslice pattern so lower it normally.
-                _ => before.push(self.lower_pat(pat)),
+                _ => before.push(self.lower_pat_mut(pat)),
             }
         }
 
@@ -214,7 +218,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 self.ban_extra_rest_pat(rest_span, prev_rest_span.unwrap(), "slice");
             } else {
                 // Lower the pattern normally.
-                after.push(self.lower_pat(pat));
+                after.push(self.lower_pat_mut(pat));
             }
         }
 
@@ -268,17 +272,17 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     }
 
     fn pat_wild_with_node_id_of(&mut self, p: &Pat) -> &'hir hir::Pat<'hir> {
-        self.pat_with_node_id_of(p, hir::PatKind::Wild)
+        self.arena.alloc(self.pat_with_node_id_of(p, hir::PatKind::Wild))
     }
 
     /// Construct a `Pat` with the `HirId` of `p.id` lowered.
-    fn pat_with_node_id_of(&mut self, p: &Pat, kind: hir::PatKind<'hir>) -> &'hir hir::Pat<'hir> {
-        self.arena.alloc(hir::Pat {
+    fn pat_with_node_id_of(&mut self, p: &Pat, kind: hir::PatKind<'hir>) -> hir::Pat<'hir> {
+        hir::Pat {
             hir_id: self.lower_node_id(p.id),
             kind,
             span: p.span,
             default_binding_modes: true,
-        })
+        }
     }
 
     /// Emit a friendly error for extra `..` patterns in a tuple/tuple struct/slice pattern.

Diff for: compiler/rustc_hir/src/hir.rs

@@ -808,13 +808,13 @@ impl<'hir> Pat<'hir> {
         }
 
         use PatKind::*;
-        match &self.kind {
+        match self.kind {
             Wild | Lit(_) | Range(..) | Binding(.., None) | Path(_) => true,
             Box(s) | Ref(s, _) | Binding(.., Some(s)) => s.walk_short_(it),
             Struct(_, fields, _) => fields.iter().all(|field| field.pat.walk_short_(it)),
             TupleStruct(_, s, _) | Tuple(s, _) | Or(s) => s.iter().all(|p| p.walk_short_(it)),
             Slice(before, slice, after) => {
-                before.iter().chain(slice.iter()).chain(after.iter()).all(|p| p.walk_short_(it))
+                before.iter().chain(slice).chain(after.iter()).all(|p| p.walk_short_(it))
             }
         }
     }
@@ -836,13 +836,13 @@ impl<'hir> Pat<'hir> {
         }
 
         use PatKind::*;
-        match &self.kind {
+        match self.kind {
             Wild | Lit(_) | Range(..) | Binding(.., None) | Path(_) => {}
             Box(s) | Ref(s, _) | Binding(.., Some(s)) => s.walk_(it),
             Struct(_, fields, _) => fields.iter().for_each(|field| field.pat.walk_(it)),
             TupleStruct(_, s, _) | Tuple(s, _) | Or(s) => s.iter().for_each(|p| p.walk_(it)),
             Slice(before, slice, after) => {
-                before.iter().chain(slice.iter()).chain(after.iter()).for_each(|p| p.walk_(it))
+                before.iter().chain(slice).chain(after.iter()).for_each(|p| p.walk_(it))
             }
         }
     }
@@ -940,19 +940,19 @@ pub enum PatKind<'hir> {
     /// A tuple struct/variant pattern `Variant(x, y, .., z)`.
     /// If the `..` pattern fragment is present, then `Option<usize>` denotes its position.
     /// `0 <= position <= subpats.len()`
-    TupleStruct(QPath<'hir>, &'hir [&'hir Pat<'hir>], Option<usize>),
+    TupleStruct(QPath<'hir>, &'hir [Pat<'hir>], Option<usize>),
 
     /// An or-pattern `A | B | C`.
     /// Invariant: `pats.len() >= 2`.
-    Or(&'hir [&'hir Pat<'hir>]),
+    Or(&'hir [Pat<'hir>]),
 
     /// A path pattern for an unit struct/variant or a (maybe-associated) constant.
     Path(QPath<'hir>),
 
     /// A tuple pattern (e.g., `(a, b)`).
     /// If the `..` pattern fragment is present, then `Option<usize>` denotes its position.
     /// `0 <= position <= subpats.len()`
-    Tuple(&'hir [&'hir Pat<'hir>], Option<usize>),
+    Tuple(&'hir [Pat<'hir>], Option<usize>),
 
     /// A `box` pattern.
     Box(&'hir Pat<'hir>),
@@ -975,7 +975,7 @@ pub enum PatKind<'hir> {
     /// ```
     /// PatKind::Slice([Binding(a), Binding(b)], Some(Wild), [Binding(c), Binding(d)])
     /// ```
-    Slice(&'hir [&'hir Pat<'hir>], Option<&'hir Pat<'hir>>, &'hir [&'hir Pat<'hir>]),
+    Slice(&'hir [Pat<'hir>], Option<&'hir Pat<'hir>>, &'hir [Pat<'hir>]),
 }
 
 #[derive(Copy, Clone, PartialEq, Encodable, Debug, HashStable_Generic)]

Diff for: compiler/rustc_mir_build/src/thir/pattern/mod.rs

@@ -325,7 +325,7 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
 
     fn lower_tuple_subpats(
         &mut self,
-        pats: &'tcx [&'tcx hir::Pat<'tcx>],
+        pats: &'tcx [hir::Pat<'tcx>],
         expected_len: usize,
         gap_pos: Option<usize>,
     ) -> Vec<FieldPat<'tcx>> {
@@ -338,7 +338,7 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
             .collect()
     }
 
-    fn lower_patterns(&mut self, pats: &'tcx [&'tcx hir::Pat<'tcx>]) -> Vec<Pat<'tcx>> {
+    fn lower_patterns(&mut self, pats: &'tcx [hir::Pat<'tcx>]) -> Vec<Pat<'tcx>> {
         pats.iter().map(|p| self.lower_pattern(p)).collect()
     }
 
@@ -350,9 +350,9 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
         &mut self,
         span: Span,
         ty: Ty<'tcx>,
-        prefix: &'tcx [&'tcx hir::Pat<'tcx>],
+        prefix: &'tcx [hir::Pat<'tcx>],
         slice: &'tcx Option<&'tcx hir::Pat<'tcx>>,
-        suffix: &'tcx [&'tcx hir::Pat<'tcx>],
+        suffix: &'tcx [hir::Pat<'tcx>],
     ) -> PatKind<'tcx> {
         let prefix = self.lower_patterns(prefix);
         let slice = self.lower_opt_pattern(slice);

Diff for: compiler/rustc_typeck/src/check/pat.rs

@@ -864,7 +864,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         &self,
         pat: &'tcx Pat<'tcx>,
         qpath: &'tcx hir::QPath<'tcx>,
-        subpats: &'tcx [&'tcx Pat<'tcx>],
+        subpats: &'tcx [Pat<'tcx>],
         ddpos: Option<usize>,
         expected: Ty<'tcx>,
         def_bm: BindingMode,
@@ -982,7 +982,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         pat_span: Span,
         res: Res,
         qpath: &hir::QPath<'_>,
-        subpats: &'tcx [&'tcx Pat<'tcx>],
+        subpats: &'tcx [Pat<'tcx>],
         fields: &'tcx [ty::FieldDef],
         expected: Ty<'tcx>,
         had_err: bool,
@@ -1112,7 +1112,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     fn check_pat_tuple(
         &self,
         span: Span,
-        elements: &'tcx [&'tcx Pat<'tcx>],
+        elements: &'tcx [Pat<'tcx>],
         ddpos: Option<usize>,
         expected: Ty<'tcx>,
         def_bm: BindingMode,
@@ -1746,9 +1746,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     fn check_pat_slice(
         &self,
         span: Span,
-        before: &'tcx [&'tcx Pat<'tcx>],
+        before: &'tcx [Pat<'tcx>],
         slice: Option<&'tcx Pat<'tcx>>,
-        after: &'tcx [&'tcx Pat<'tcx>],
+        after: &'tcx [Pat<'tcx>],
         expected: Ty<'tcx>,
         def_bm: BindingMode,
         ti: TopInfo<'tcx>,

Diff for: src/librustdoc/clean/utils.rs

@@ -260,17 +260,12 @@ crate fn name_from_pat(p: &hir::Pat<'_>) -> Symbol {
         PatKind::Wild | PatKind::Struct(..) => return kw::Underscore,
         PatKind::Binding(_, _, ident, _) => return ident.name,
         PatKind::TupleStruct(ref p, ..) | PatKind::Path(ref p) => qpath_to_string(p),
-        PatKind::Or(ref pats) => pats
-            .iter()
-            .map(|p| name_from_pat(&**p).to_string())
-            .collect::<Vec<String>>()
-            .join(" | "),
+        PatKind::Or(ref pats) => {
+            pats.iter().map(|p| name_from_pat(p).to_string()).collect::<Vec<String>>().join(" | ")
+        }
         PatKind::Tuple(ref elts, _) => format!(
             "({})",
-            elts.iter()
-                .map(|p| name_from_pat(&**p).to_string())
-                .collect::<Vec<String>>()
-                .join(", ")
+            elts.iter().map(|p| name_from_pat(p).to_string()).collect::<Vec<String>>().join(", ")
         ),
         PatKind::Box(ref p) => return name_from_pat(&**p),
         PatKind::Ref(ref p, _) => return name_from_pat(&**p),
@@ -282,9 +277,9 @@ crate fn name_from_pat(p: &hir::Pat<'_>) -> Symbol {
         }
         PatKind::Range(..) => return kw::Underscore,
         PatKind::Slice(ref begin, ref mid, ref end) => {
-            let begin = begin.iter().map(|p| name_from_pat(&**p).to_string());
+            let begin = begin.iter().map(|p| name_from_pat(p).to_string());
             let mid = mid.as_ref().map(|p| format!("..{}", name_from_pat(&**p))).into_iter();
-            let end = end.iter().map(|p| name_from_pat(&**p).to_string());
+            let end = end.iter().map(|p| name_from_pat(p).to_string());
             format!("[{}]", begin.chain(mid).chain(end).collect::<Vec<_>>().join(", "))
         }
     })

Diff for: src/tools/clippy/clippy_lints/src/manual_unwrap_or.rs

@@ -61,13 +61,13 @@ fn lint_manual_unwrap_or<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
             if let Some((idx, or_arm)) = arms.iter().enumerate().find(|(_, arm)| {
                 match arm.pat.kind {
                     PatKind::Path(ref qpath) => is_lang_ctor(cx, qpath, OptionNone),
-                    PatKind::TupleStruct(ref qpath, &[pat], _) =>
+                    PatKind::TupleStruct(ref qpath, [pat], _) =>
                         matches!(pat.kind, PatKind::Wild) && is_lang_ctor(cx, qpath, ResultErr),
                     _ => false,
                 }
             });
             let unwrap_arm = &arms[1 - idx];
-            if let PatKind::TupleStruct(ref qpath, &[unwrap_pat], _) = unwrap_arm.pat.kind;
+            if let PatKind::TupleStruct(ref qpath, [unwrap_pat], _) = unwrap_arm.pat.kind;
             if is_lang_ctor(cx, qpath, OptionSome) || is_lang_ctor(cx, qpath, ResultOk);
             if let PatKind::Binding(_, binding_hir_id, ..) = unwrap_pat.kind;
             if path_to_local_id(unwrap_arm.body, binding_hir_id);

Diff for: src/tools/clippy/clippy_lints/src/matches.rs

@@ -625,7 +625,7 @@ impl<'tcx> LateLintPass<'tcx> for Matches {
             if let PatKind::TupleStruct(
                 QPath::Resolved(None, variant_name), args, _) = arms[0].pat.kind;
             if args.len() == 1;
-            if let PatKind::Binding(_, arg, ..) = strip_pat_refs(args[0]).kind;
+            if let PatKind::Binding(_, arg, ..) = strip_pat_refs(&args[0]).kind;
             let body = remove_blocks(arms[0].body);
             if path_to_local_id(body, arg);