Rollup merge of #124047 - Jules-Bertholet:match-ergonomics-cleanups, …

…r=Nadrieril

Match ergonomics 2024: miscellaneous code cleanups

- Store `ByRef` instead of `BindingAnnotation` in `PatInfo`
- Rename `BindingAnnotation` to `BindingMode`

r? ``@Nadrieril``

cc #123076

``@rustbot`` label A-patterns

compiler/rustc_ast/src/ast.rs

@@ -568,7 +568,7 @@ impl Pat {
             // In a type expression `_` is an inference variable.
             PatKind::Wild => TyKind::Infer,
             // An IDENT pattern with no binding mode would be valid as path to a type. E.g. `u32`.
-            PatKind::Ident(BindingAnnotation::NONE, ident, None) => {
+            PatKind::Ident(BindingMode::NONE, ident, None) => {
                 TyKind::Path(None, Path::from_ident(*ident))
             }
             PatKind::Path(qself, path) => TyKind::Path(qself.clone(), path.clone()),
@@ -675,7 +675,7 @@ impl Pat {
     pub fn descr(&self) -> Option<String> {
         match &self.kind {
             PatKind::Wild => Some("_".to_string()),
-            PatKind::Ident(BindingAnnotation::NONE, ident, None) => Some(format!("{ident}")),
+            PatKind::Ident(BindingMode::NONE, ident, None) => Some(format!("{ident}")),
             PatKind::Ref(pat, mutbl) => pat.descr().map(|d| format!("&{}{d}", mutbl.prefix_str())),
             _ => None,
         }
@@ -707,14 +707,25 @@ pub enum ByRef {
     No,
 }
 
-/// Explicit binding annotations given in the HIR for a binding. Note
-/// that this is not the final binding *mode* that we infer after type
-/// inference.
+impl ByRef {
+    pub fn cap_ref_mutability(mut self, mutbl: Mutability) -> Self {
+        if let ByRef::Yes(old_mutbl) = &mut self {
+            *old_mutbl = cmp::min(*old_mutbl, mutbl);
+        }
+        self
+    }
+}
+
+/// The mode of a binding (`mut`, `ref mut`, etc).
+/// Used for both the explicit binding annotations given in the HIR for a binding
+/// and the final binding mode that we infer after type inference/match ergonomics.
+/// `.0` is the by-reference mode (`ref`, `ref mut`, or by value),
+/// `.1` is the mutability of the binding.
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 #[derive(Encodable, Decodable, HashStable_Generic)]
-pub struct BindingAnnotation(pub ByRef, pub Mutability);
+pub struct BindingMode(pub ByRef, pub Mutability);
 
-impl BindingAnnotation {
+impl BindingMode {
     pub const NONE: Self = Self(ByRef::No, Mutability::Not);
     pub const REF: Self = Self(ByRef::Yes(Mutability::Not), Mutability::Not);
     pub const MUT: Self = Self(ByRef::No, Mutability::Mut);
@@ -732,13 +743,6 @@ impl BindingAnnotation {
             Self::MUT_REF_MUT => "mut ref mut ",
         }
     }
-
-    pub fn cap_ref_mutability(mut self, mutbl: Mutability) -> Self {
-        if let ByRef::Yes(old_mutbl) = &mut self.0 {
-            *old_mutbl = cmp::min(*old_mutbl, mutbl);
-        }
-        self
-    }
 }
 
 #[derive(Clone, Encodable, Decodable, Debug)]
@@ -769,7 +773,7 @@ pub enum PatKind {
     /// or a unit struct/variant pattern, or a const pattern (in the last two cases the third
     /// field must be `None`). Disambiguation cannot be done with parser alone, so it happens
     /// during name resolution.
-    Ident(BindingAnnotation, Ident, Option<P<Pat>>),
+    Ident(BindingMode, Ident, Option<P<Pat>>),
 
     /// A struct or struct variant pattern (e.g., `Variant {x, y, ..}`).
     Struct(Option<P<QSelf>>, Path, ThinVec<PatField>, PatFieldsRest),
@@ -2382,7 +2386,7 @@ pub type ExplicitSelf = Spanned<SelfKind>;
 impl Param {
     /// Attempts to cast parameter to `ExplicitSelf`.
     pub fn to_self(&self) -> Option<ExplicitSelf> {
-        if let PatKind::Ident(BindingAnnotation(ByRef::No, mutbl), ident, _) = self.pat.kind {
+        if let PatKind::Ident(BindingMode(ByRef::No, mutbl), ident, _) = self.pat.kind {
             if ident.name == kw::SelfLower {
                 return match self.ty.kind {
                     TyKind::ImplicitSelf => Some(respan(self.pat.span, SelfKind::Value(mutbl))),
@@ -2434,7 +2438,7 @@ impl Param {
             attrs,
             pat: P(Pat {
                 id: DUMMY_NODE_ID,
-                kind: PatKind::Ident(BindingAnnotation(ByRef::No, mutbl), eself_ident, None),
+                kind: PatKind::Ident(BindingMode(ByRef::No, mutbl), eself_ident, None),
                 span,
                 tokens: None,
             }),

compiler/rustc_ast_lowering/src/delegation.rs

@@ -178,7 +178,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         let pat_id = self.lower_node_id(pat_node_id);
         let pat = self.arena.alloc(hir::Pat {
             hir_id: pat_id,
-            kind: hir::PatKind::Binding(hir::BindingAnnotation::NONE, pat_id, Ident::empty(), None),
+            kind: hir::PatKind::Binding(hir::BindingMode::NONE, pat_id, Ident::empty(), None),
             span: ty.span,
             default_binding_modes: false,
         });

compiler/rustc_ast_lowering/src/expr.rs

@@ -643,7 +643,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 let (pat, task_context_hid) = self.pat_ident_binding_mode(
                     span,
                     Ident::with_dummy_span(sym::_task_context),
-                    hir::BindingAnnotation::MUT,
+                    hir::BindingMode::MUT,
                 );
                 let param = hir::Param {
                     hir_id: self.next_id(),
@@ -805,11 +805,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
         // debuggers and debugger extensions expect it to be called `__awaitee`. They use
         // this name to identify what is being awaited by a suspended async functions.
         let awaitee_ident = Ident::with_dummy_span(sym::__awaitee);
-        let (awaitee_pat, awaitee_pat_hid) = self.pat_ident_binding_mode(
-            gen_future_span,
-            awaitee_ident,
-            hir::BindingAnnotation::MUT,
-        );
+        let (awaitee_pat, awaitee_pat_hid) =
+            self.pat_ident_binding_mode(gen_future_span, awaitee_ident, hir::BindingMode::MUT);
 
         let task_context_ident = Ident::with_dummy_span(sym::_task_context);
 
@@ -1648,7 +1645,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         // `mut iter`
         let iter = Ident::with_dummy_span(sym::iter);
         let (iter_pat, iter_pat_nid) =
-            self.pat_ident_binding_mode(head_span, iter, hir::BindingAnnotation::MUT);
+            self.pat_ident_binding_mode(head_span, iter, hir::BindingMode::MUT);
 
         let match_expr = {
             let iter = self.expr_ident(head_span, iter, iter_pat_nid);

compiler/rustc_ast_lowering/src/item.rs

@@ -1179,9 +1179,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             // Check if this is a binding pattern, if so, we can optimize and avoid adding a
             // `let <pat> = __argN;` statement. In this case, we do not rename the parameter.
             let (ident, is_simple_parameter) = match parameter.pat.kind {
-                hir::PatKind::Binding(hir::BindingAnnotation(ByRef::No, _), _, ident, _) => {
-                    (ident, true)
-                }
+                hir::PatKind::Binding(hir::BindingMode(ByRef::No, _), _, ident, _) => (ident, true),
                 // For `ref mut` or wildcard arguments, we can't reuse the binding, but
                 // we can keep the same name for the parameter.
                 // This lets rustdoc render it correctly in documentation.
@@ -1244,7 +1242,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 // because the user may have specified a `ref mut` binding in the next
                 // statement.
                 let (move_pat, move_id) =
-                    self.pat_ident_binding_mode(desugared_span, ident, hir::BindingAnnotation::MUT);
+                    self.pat_ident_binding_mode(desugared_span, ident, hir::BindingMode::MUT);
                 let move_expr = self.expr_ident(desugared_span, ident, new_parameter_id);
                 let move_stmt = self.stmt_let_pat(
                     None,

compiler/rustc_ast_lowering/src/lib.rs

@@ -1895,7 +1895,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             implicit_self: decl.inputs.get(0).map_or(hir::ImplicitSelfKind::None, |arg| {
                 let is_mutable_pat = matches!(
                     arg.pat.kind,
-                    PatKind::Ident(hir::BindingAnnotation(_, Mutability::Mut), ..)
+                    PatKind::Ident(hir::BindingMode(_, Mutability::Mut), ..)
                 );
 
                 match &arg.ty.kind {
@@ -2478,18 +2478,18 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     }
 
     fn pat_ident(&mut self, span: Span, ident: Ident) -> (&'hir hir::Pat<'hir>, HirId) {
-        self.pat_ident_binding_mode(span, ident, hir::BindingAnnotation::NONE)
+        self.pat_ident_binding_mode(span, ident, hir::BindingMode::NONE)
     }
 
     fn pat_ident_mut(&mut self, span: Span, ident: Ident) -> (hir::Pat<'hir>, HirId) {
-        self.pat_ident_binding_mode_mut(span, ident, hir::BindingAnnotation::NONE)
+        self.pat_ident_binding_mode_mut(span, ident, hir::BindingMode::NONE)
     }
 
     fn pat_ident_binding_mode(
         &mut self,
         span: Span,
         ident: Ident,
-        bm: hir::BindingAnnotation,
+        bm: hir::BindingMode,
     ) -> (&'hir hir::Pat<'hir>, HirId) {
         let (pat, hir_id) = self.pat_ident_binding_mode_mut(span, ident, bm);
         (self.arena.alloc(pat), hir_id)
@@ -2499,7 +2499,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         &mut self,
         span: Span,
         ident: Ident,
-        bm: hir::BindingAnnotation,
+        bm: hir::BindingMode,
     ) -> (hir::Pat<'hir>, HirId) {
         let hir_id = self.next_id();
 

compiler/rustc_ast_lowering/src/pat.rs

@@ -243,7 +243,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     fn lower_pat_ident(
         &mut self,
         p: &Pat,
-        annotation: BindingAnnotation,
+        annotation: BindingMode,
         ident: Ident,
         lower_sub: impl FnOnce(&mut Self) -> Option<&'hir hir::Pat<'hir>>,
     ) -> hir::PatKind<'hir> {

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -276,8 +276,8 @@ impl<'a> AstValidator<'a> {
     fn check_decl_no_pat(decl: &FnDecl, mut report_err: impl FnMut(Span, Option<Ident>, bool)) {
         for Param { pat, .. } in &decl.inputs {
             match pat.kind {
-                PatKind::Ident(BindingAnnotation::NONE, _, None) | PatKind::Wild => {}
-                PatKind::Ident(BindingAnnotation::MUT, ident, None) => {
+                PatKind::Ident(BindingMode::NONE, _, None) | PatKind::Wild => {}
+                PatKind::Ident(BindingMode::MUT, ident, None) => {
                     report_err(pat.span, Some(ident), true)
                 }
                 _ => report_err(pat.span, None, false),

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -17,7 +17,7 @@ use rustc_ast::util::classify;
 use rustc_ast::util::comments::{Comment, CommentStyle};
 use rustc_ast::util::parser;
 use rustc_ast::{self as ast, AttrArgs, AttrArgsEq, BlockCheckMode, PatKind};
-use rustc_ast::{attr, BindingAnnotation, ByRef, DelimArgs, RangeEnd, RangeSyntax, Term};
+use rustc_ast::{attr, BindingMode, ByRef, DelimArgs, RangeEnd, RangeSyntax, Term};
 use rustc_ast::{GenericArg, GenericBound, SelfKind};
 use rustc_ast::{InlineAsmOperand, InlineAsmRegOrRegClass};
 use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
@@ -1558,7 +1558,7 @@ impl<'a> State<'a> {
         match &pat.kind {
             PatKind::Wild => self.word("_"),
             PatKind::Never => self.word("!"),
-            PatKind::Ident(BindingAnnotation(by_ref, mutbl), ident, sub) => {
+            PatKind::Ident(BindingMode(by_ref, mutbl), ident, sub) => {
                 if mutbl.is_mut() {
                     self.word_nbsp("mut");
                 }
@@ -1654,7 +1654,7 @@ impl<'a> State<'a> {
                 if mutbl.is_mut() {
                     self.word("mut ");
                 }
-                if let PatKind::Ident(ast::BindingAnnotation::MUT, ..) = inner.kind {
+                if let PatKind::Ident(ast::BindingMode::MUT, ..) = inner.kind {
                     self.popen();
                     self.print_pat(inner);
                     self.pclose();

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -377,7 +377,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 if p.span == self.expr_span {
                     self.pat = Some(p);
                 }
-                if let hir::PatKind::Binding(hir::BindingAnnotation::NONE, _, i, sub) = p.kind {
+                if let hir::PatKind::Binding(hir::BindingMode::NONE, _, i, sub) = p.kind {
                     if i.span == self.expr_span || p.span == self.expr_span {
                         self.pat = Some(p);
                     }

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -5,7 +5,7 @@ use core::ops::ControlFlow;
 use hir::{ExprKind, Param};
 use rustc_errors::{Applicability, Diag};
 use rustc_hir::intravisit::Visitor;
-use rustc_hir::{self as hir, BindingAnnotation, ByRef, Node};
+use rustc_hir::{self as hir, BindingMode, ByRef, Node};
 use rustc_infer::traits;
 use rustc_middle::mir::{Mutability, Place, PlaceRef, ProjectionElem};
 use rustc_middle::ty::{self, InstanceDef, ToPredicate, Ty, TyCtxt};
@@ -303,7 +303,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                 {
                     match *decl.local_info() {
                         LocalInfo::User(BindingForm::Var(mir::VarBindingForm {
-                            binding_mode: BindingAnnotation(ByRef::No, Mutability::Not),
+                            binding_mode: BindingMode(ByRef::No, Mutability::Not),
                             opt_ty_info: Some(sp),
                             opt_match_place: _,
                             pat_span: _,
@@ -398,7 +398,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                 let upvar_hir_id = captured_place.get_root_variable();
 
                 if let Node::Pat(pat) = self.infcx.tcx.hir_node(upvar_hir_id)
-                    && let hir::PatKind::Binding(hir::BindingAnnotation::NONE, _, upvar_ident, _) =
+                    && let hir::PatKind::Binding(hir::BindingMode::NONE, _, upvar_ident, _) =
                         pat.kind
                 {
                     if upvar_ident.name == kw::SelfLower {
@@ -729,7 +729,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         debug!("local_decl: {:?}", local_decl);
         let pat_span = match *local_decl.local_info() {
             LocalInfo::User(BindingForm::Var(mir::VarBindingForm {
-                binding_mode: BindingAnnotation(ByRef::No, Mutability::Not),
+                binding_mode: BindingMode(ByRef::No, Mutability::Not),
                 opt_ty_info: _,
                 opt_match_place: _,
                 pat_span,
@@ -1086,7 +1086,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
             }
 
             LocalInfo::User(mir::BindingForm::Var(mir::VarBindingForm {
-                binding_mode: BindingAnnotation(ByRef::No, _),
+                binding_mode: BindingMode(ByRef::No, _),
                 opt_ty_info,
                 ..
             })) => {
@@ -1154,7 +1154,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
             }
 
             LocalInfo::User(mir::BindingForm::Var(mir::VarBindingForm {
-                binding_mode: BindingAnnotation(ByRef::Yes(_), _),
+                binding_mode: BindingMode(ByRef::Yes(_), _),
                 ..
             })) => {
                 let pattern_span: Span = local_decl.source_info.span;
@@ -1356,7 +1356,7 @@ pub fn mut_borrow_of_mutable_ref(local_decl: &LocalDecl<'_>, local_name: Option<
     match *local_decl.local_info() {
         // Check if mutably borrowing a mutable reference.
         LocalInfo::User(mir::BindingForm::Var(mir::VarBindingForm {
-            binding_mode: BindingAnnotation(ByRef::No, Mutability::Not),
+            binding_mode: BindingMode(ByRef::No, Mutability::Not),
             ..
         })) => matches!(local_decl.ty.kind(), ty::Ref(_, _, hir::Mutability::Mut)),
         LocalInfo::User(mir::BindingForm::ImplicitSelf(kind)) => {

compiler/rustc_builtin_macros/src/deriving/generic/mod.rs

@@ -180,7 +180,7 @@ pub use SubstructureFields::*;
 use crate::{deriving, errors};
 use rustc_ast::ptr::P;
 use rustc_ast::{
-    self as ast, BindingAnnotation, ByRef, EnumDef, Expr, GenericArg, GenericParamKind, Generics,
+    self as ast, BindingMode, ByRef, EnumDef, Expr, GenericArg, GenericParamKind, Generics,
     Mutability, PatKind, TyKind, VariantData,
 };
 use rustc_attr as attr;
@@ -1479,11 +1479,7 @@ impl<'a> TraitDef<'a> {
                             struct_field.ident,
                             cx.pat(
                                 path.span,
-                                PatKind::Ident(
-                                    BindingAnnotation(by_ref, Mutability::Not),
-                                    path,
-                                    None,
-                                ),
+                                PatKind::Ident(BindingMode(by_ref, Mutability::Not), path, None),
                             ),
                         )
                     });

compiler/rustc_expand/src/build.rs

@@ -202,7 +202,7 @@ impl<'a> ExtCtxt<'a> {
         ex: P<ast::Expr>,
     ) -> ast::Stmt {
         let pat = if mutbl {
-            self.pat_ident_binding_mode(sp, ident, ast::BindingAnnotation::MUT)
+            self.pat_ident_binding_mode(sp, ident, ast::BindingMode::MUT)
         } else {
             self.pat_ident(sp, ident)
         };
@@ -490,14 +490,14 @@ impl<'a> ExtCtxt<'a> {
         self.pat(span, PatKind::Lit(expr))
     }
     pub fn pat_ident(&self, span: Span, ident: Ident) -> P<ast::Pat> {
-        self.pat_ident_binding_mode(span, ident, ast::BindingAnnotation::NONE)
+        self.pat_ident_binding_mode(span, ident, ast::BindingMode::NONE)
     }
 
     pub fn pat_ident_binding_mode(
         &self,
         span: Span,
         ident: Ident,
-        ann: ast::BindingAnnotation,
+        ann: ast::BindingMode,
     ) -> P<ast::Pat> {
         let pat = PatKind::Ident(ann, ident.with_span_pos(span), None);
         self.pat(span, pat)

compiler/rustc_hir/src/hir.rs

@@ -7,7 +7,7 @@ use crate::LangItem;
 use rustc_ast as ast;
 use rustc_ast::util::parser::ExprPrecedence;
 use rustc_ast::{Attribute, FloatTy, IntTy, Label, LitKind, TraitObjectSyntax, UintTy};
-pub use rustc_ast::{BinOp, BinOpKind, BindingAnnotation, BorrowKind, ByRef, CaptureBy};
+pub use rustc_ast::{BinOp, BinOpKind, BindingMode, BorrowKind, ByRef, CaptureBy};
 pub use rustc_ast::{ImplPolarity, IsAuto, Movability, Mutability, UnOp};
 use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
 use rustc_data_structures::fingerprint::Fingerprint;
@@ -1151,7 +1151,7 @@ pub enum PatKind<'hir> {
     /// The `HirId` is the canonical ID for the variable being bound,
     /// (e.g., in `Ok(x) | Err(x)`, both `x` use the same canonical ID),
     /// which is the pattern ID of the first `x`.
-    Binding(BindingAnnotation, HirId, Ident, Option<&'hir Pat<'hir>>),
+    Binding(BindingMode, HirId, Ident, Option<&'hir Pat<'hir>>),
 
     /// A struct or struct variant pattern (e.g., `Variant {x, y, ..}`).
     /// The `bool` is `true` in the presence of a `..`.