Refactor and re-use BindingAnnotation

25 files changed, 174 insertions, 223 deletions

diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs
index 3af6dee9e43..f05f58d63a3 100644
--- a/compiler/rustc_ast/src/ast.rs
+++ b/compiler/rustc_ast/src/ast.rs
@@ -594,7 +594,7 @@ 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(BindingMode::ByValue(Mutability::Not), ident, None) => {
+            PatKind::Ident(BindingAnnotation::NONE, ident, None) => {
                 TyKind::Path(None, Path::from_ident(*ident))
             }
             PatKind::Path(qself, path) => TyKind::Path(qself.clone(), path.clone()),
@@ -681,10 +681,43 @@ pub struct PatField {
     pub is_placeholder: bool,
 }
 
-#[derive(Clone, PartialEq, Encodable, Decodable, Debug, Copy)]
-pub enum BindingMode {
-    ByRef(Mutability),
-    ByValue(Mutability),
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+#[derive(Encodable, Decodable, HashStable_Generic)]
+pub enum ByRef {
+    Yes,
+    No,
+}
+
+impl From<bool> for ByRef {
+    fn from(b: bool) -> ByRef {
+        match b {
+            false => ByRef::No,
+            true => ByRef::Yes,
+        }
+    }
+}
+
+/// 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.
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+#[derive(Encodable, Decodable, HashStable_Generic)]
+pub struct BindingAnnotation(pub ByRef, pub Mutability);
+
+impl BindingAnnotation {
+    pub const NONE: Self = Self(ByRef::No, Mutability::Not);
+    pub const REF: Self = Self(ByRef::Yes, Mutability::Not);
+    pub const MUT: Self = Self(ByRef::No, Mutability::Mut);
+    pub const REF_MUT: Self = Self(ByRef::Yes, Mutability::Mut);
+
+    pub fn prefix_str(self) -> &'static str {
+        match self {
+            Self::NONE => "",
+            Self::REF => "ref ",
+            Self::MUT => "mut ",
+            Self::REF_MUT => "ref mut ",
+        }
+    }
 }
 
 #[derive(Clone, Encodable, Decodable, Debug)]
@@ -713,7 +746,7 @@ 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(BindingMode, Ident, Option<P<Pat>>),
+    Ident(BindingAnnotation, Ident, Option<P<Pat>>),
 
     /// A struct or struct variant pattern (e.g., `Variant {x, y, ..}`).
     /// The `bool` is `true` in the presence of a `..`.
@@ -2228,7 +2261,7 @@ pub type ExplicitSelf = Spanned<SelfKind>;
 impl Param {
     /// Attempts to cast parameter to `ExplicitSelf`.
     pub fn to_self(&self) -> Option<ExplicitSelf> {
-        if let PatKind::Ident(BindingMode::ByValue(mutbl), ident, _) = self.pat.kind {
+        if let PatKind::Ident(BindingAnnotation(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))),
@@ -2258,11 +2291,24 @@ impl Param {
     pub fn from_self(attrs: AttrVec, eself: ExplicitSelf, eself_ident: Ident) -> Param {
         let span = eself.span.to(eself_ident.span);
         let infer_ty = P(Ty { id: DUMMY_NODE_ID, kind: TyKind::ImplicitSelf, span, tokens: None });
-        let param = |mutbl, ty| Param {
+        let (mutbl, ty) = match eself.node {
+            SelfKind::Explicit(ty, mutbl) => (mutbl, ty),
+            SelfKind::Value(mutbl) => (mutbl, infer_ty),
+            SelfKind::Region(lt, mutbl) => (
+                Mutability::Not,
+                P(Ty {
+                    id: DUMMY_NODE_ID,
+                    kind: TyKind::Rptr(lt, MutTy { ty: infer_ty, mutbl }),
+                    span,
+                    tokens: None,
+                }),
+            ),
+        };
+        Param {
             attrs,
             pat: P(Pat {
                 id: DUMMY_NODE_ID,
-                kind: PatKind::Ident(BindingMode::ByValue(mutbl), eself_ident, None),
+                kind: PatKind::Ident(BindingAnnotation(ByRef::No, mutbl), eself_ident, None),
                 span,
                 tokens: None,
             }),
@@ -2270,19 +2316,6 @@ impl Param {
             ty,
             id: DUMMY_NODE_ID,
             is_placeholder: false,
-        };
-        match eself.node {
-            SelfKind::Explicit(ty, mutbl) => param(mutbl, ty),
-            SelfKind::Value(mutbl) => param(mutbl, infer_ty),
-            SelfKind::Region(lt, mutbl) => param(
-                Mutability::Not,
-                P(Ty {
-                    id: DUMMY_NODE_ID,
-                    kind: TyKind::Rptr(lt, MutTy { ty: infer_ty, mutbl }),
-                    span,
-                    tokens: None,
-                }),
-            ),
         }
     }
 }
diff --git a/compiler/rustc_ast_lowering/src/expr.rs b/compiler/rustc_ast_lowering/src/expr.rs
index 7df3520422c..7d3f839c922 100644
--- a/compiler/rustc_ast_lowering/src/expr.rs
+++ b/compiler/rustc_ast_lowering/src/expr.rs
@@ -577,7 +577,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         let (pat, task_context_hid) = self.pat_ident_binding_mode(
             span,
             Ident::with_dummy_span(sym::_task_context),
-            hir::BindingAnnotation::Mutable,
+            hir::BindingAnnotation::MUT,
         );
         let param = hir::Param {
             hir_id: self.next_id(),
@@ -671,7 +671,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         // 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(span, awaitee_ident, hir::BindingAnnotation::Mutable);
+            self.pat_ident_binding_mode(span, awaitee_ident, hir::BindingAnnotation::MUT);
 
         let task_context_ident = Ident::with_dummy_span(sym::_task_context);
 
@@ -1433,7 +1433,7 @@ 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::Mutable);
+            self.pat_ident_binding_mode(head_span, iter, hir::BindingAnnotation::MUT);
 
         // `match Iterator::next(&mut iter) { ... }`
         let match_expr = {
diff --git a/compiler/rustc_ast_lowering/src/item.rs b/compiler/rustc_ast_lowering/src/item.rs
index fd338ffc0c5..810ee6eb76d 100644
--- a/compiler/rustc_ast_lowering/src/item.rs
+++ b/compiler/rustc_ast_lowering/src/item.rs
@@ -1074,12 +1074,9 @@ 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::Unannotated | hir::BindingAnnotation::Mutable,
-                        _,
-                        ident,
-                        _,
-                    ) => (ident, true),
+                    hir::PatKind::Binding(hir::BindingAnnotation(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.
@@ -1144,7 +1141,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     let (move_pat, move_id) = this.pat_ident_binding_mode(
                         desugared_span,
                         ident,
-                        hir::BindingAnnotation::Mutable,
+                        hir::BindingAnnotation::MUT,
                     );
                     let move_expr = this.expr_ident(desugared_span, ident, new_parameter_id);
                     let move_stmt = this.stmt_let_pat(
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index 9a960356a85..62ea49e8df9 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -1696,10 +1696,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             output,
             c_variadic,
             implicit_self: decl.inputs.get(0).map_or(hir::ImplicitSelfKind::None, |arg| {
-                use BindingMode::{ByRef, ByValue};
                 let is_mutable_pat = matches!(
                     arg.pat.kind,
-                    PatKind::Ident(ByValue(Mutability::Mut) | ByRef(Mutability::Mut), ..)
+                    PatKind::Ident(hir::BindingAnnotation(_, Mutability::Mut), ..)
                 );
 
                 match arg.ty.kind {
@@ -2361,11 +2360,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     }
 
     fn pat_ident(&mut self, span: Span, ident: Ident) -> (&'hir hir::Pat<'hir>, hir::HirId) {
-        self.pat_ident_binding_mode(span, ident, hir::BindingAnnotation::Unannotated)
+        self.pat_ident_binding_mode(span, ident, hir::BindingAnnotation::NONE)
     }
 
     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)
+        self.pat_ident_binding_mode_mut(span, ident, hir::BindingAnnotation::NONE)
     }
 
     fn pat_ident_binding_mode(
diff --git a/compiler/rustc_ast_lowering/src/pat.rs b/compiler/rustc_ast_lowering/src/pat.rs
index 1efa19a3a82..c185a0d31bd 100644
--- a/compiler/rustc_ast_lowering/src/pat.rs
+++ b/compiler/rustc_ast_lowering/src/pat.rs
@@ -24,7 +24,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             let node = loop {
                 match pattern.kind {
                     PatKind::Wild => break hir::PatKind::Wild,
-                    PatKind::Ident(ref binding_mode, ident, ref sub) => {
+                    PatKind::Ident(binding_mode, ident, ref sub) => {
                         let lower_sub = |this: &mut Self| sub.as_ref().map(|s| this.lower_pat(&*s));
                         break self.lower_pat_ident(pattern, binding_mode, ident, lower_sub);
                     }
@@ -176,9 +176,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         let mut prev_rest_span = None;
 
         // Lowers `$bm $ident @ ..` to `$bm $ident @ _`.
-        let lower_rest_sub = |this: &mut Self, pat, bm, ident, sub| {
+        let lower_rest_sub = |this: &mut Self, pat, ann, ident, sub| {
             let lower_sub = |this: &mut Self| Some(this.pat_wild_with_node_id_of(sub));
-            let node = this.lower_pat_ident(pat, bm, ident, lower_sub);
+            let node = this.lower_pat_ident(pat, ann, ident, lower_sub);
             this.pat_with_node_id_of(pat, node)
         };
 
@@ -194,9 +194,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 }
                 // Found a sub-slice pattern `$binding_mode $ident @ ..`.
                 // Record, lower it to `$binding_mode $ident @ _`, and stop here.
-                PatKind::Ident(ref bm, ident, Some(ref sub)) if sub.is_rest() => {
+                PatKind::Ident(ann, ident, Some(ref sub)) if sub.is_rest() => {
                     prev_rest_span = Some(sub.span);
-                    slice = Some(self.arena.alloc(lower_rest_sub(self, pat, bm, ident, sub)));
+                    slice = Some(self.arena.alloc(lower_rest_sub(self, pat, ann, ident, sub)));
                     break;
                 }
                 // It was not a subslice pattern so lower it normally.
@@ -209,9 +209,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             // There was a previous subslice pattern; make sure we don't allow more.
             let rest_span = match pat.kind {
                 PatKind::Rest => Some(pat.span),
-                PatKind::Ident(ref bm, ident, Some(ref sub)) if sub.is_rest() => {
+                PatKind::Ident(ann, ident, Some(ref sub)) if sub.is_rest() => {
                     // #69103: Lower into `binding @ _` as above to avoid ICEs.
-                    after.push(lower_rest_sub(self, pat, bm, ident, sub));
+                    after.push(lower_rest_sub(self, pat, ann, ident, sub));
                     Some(sub.span)
                 }
                 _ => None,
@@ -235,7 +235,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     fn lower_pat_ident(
         &mut self,
         p: &Pat,
-        binding_mode: &BindingMode,
+        annotation: BindingAnnotation,
         ident: Ident,
         lower_sub: impl FnOnce(&mut Self) -> Option<&'hir hir::Pat<'hir>>,
     ) -> hir::PatKind<'hir> {
@@ -248,7 +248,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 };
 
                 hir::PatKind::Binding(
-                    self.lower_binding_mode(binding_mode),
+                    annotation,
                     self.lower_node_id(canonical_id),
                     self.lower_ident(ident),
                     lower_sub(self),
@@ -265,15 +265,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         }
     }
 
-    fn lower_binding_mode(&mut self, b: &BindingMode) -> hir::BindingAnnotation {
-        match *b {
-            BindingMode::ByValue(Mutability::Not) => hir::BindingAnnotation::Unannotated,
-            BindingMode::ByRef(Mutability::Not) => hir::BindingAnnotation::Ref,
-            BindingMode::ByValue(Mutability::Mut) => hir::BindingAnnotation::Mutable,
-            BindingMode::ByRef(Mutability::Mut) => hir::BindingAnnotation::RefMut,
-        }
-    }
-
     fn pat_wild_with_node_id_of(&mut self, p: &Pat) -> &'hir hir::Pat<'hir> {
         self.arena.alloc(self.pat_with_node_id_of(p, hir::PatKind::Wild))
     }
diff --git a/compiler/rustc_ast_passes/src/ast_validation.rs b/compiler/rustc_ast_passes/src/ast_validation.rs
index 23464bf0a5a..d6d8881a53a 100644
--- a/compiler/rustc_ast_passes/src/ast_validation.rs
+++ b/compiler/rustc_ast_passes/src/ast_validation.rs
@@ -281,8 +281,8 @@ 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(BindingMode::ByValue(Mutability::Not), _, None) | PatKind::Wild => {}
-                PatKind::Ident(BindingMode::ByValue(Mutability::Mut), ident, None) => {
+                PatKind::Ident(BindingAnnotation::NONE, _, None) | PatKind::Wild => {}
+                PatKind::Ident(BindingAnnotation::MUT, ident, None) => {
                     report_err(pat.span, Some(ident), true)
                 }
                 _ => report_err(pat.span, None, false),
diff --git a/compiler/rustc_ast_pretty/src/pprust/state.rs b/compiler/rustc_ast_pretty/src/pprust/state.rs
index 8749a13c5dd..ed5e7dace4b 100644
--- a/compiler/rustc_ast_pretty/src/pprust/state.rs
+++ b/compiler/rustc_ast_pretty/src/pprust/state.rs
@@ -11,8 +11,8 @@ use rustc_ast::tokenstream::{TokenStream, TokenTree};
 use rustc_ast::util::classify;
 use rustc_ast::util::comments::{gather_comments, Comment, CommentStyle};
 use rustc_ast::util::parser;
-use rustc_ast::{self as ast, BlockCheckMode, PatKind, RangeEnd, RangeSyntax};
-use rustc_ast::{attr, Term};
+use rustc_ast::{self as ast, BlockCheckMode, Mutability, PatKind, RangeEnd, RangeSyntax};
+use rustc_ast::{attr, BindingAnnotation, ByRef, Term};
 use rustc_ast::{GenericArg, MacArgs, MacArgsEq};
 use rustc_ast::{GenericBound, SelfKind, TraitBoundModifier};
 use rustc_ast::{InlineAsmOperand, InlineAsmRegOrRegClass};
@@ -1399,16 +1399,12 @@ impl<'a> State<'a> {
         is that it doesn't matter */
         match pat.kind {
             PatKind::Wild => self.word("_"),
-            PatKind::Ident(binding_mode, ident, ref sub) => {
-                match binding_mode {
-                    ast::BindingMode::ByRef(mutbl) => {
-                        self.word_nbsp("ref");
-                        self.print_mutability(mutbl, false);
-                    }
-                    ast::BindingMode::ByValue(ast::Mutability::Not) => {}
-                    ast::BindingMode::ByValue(ast::Mutability::Mut) => {
-                        self.word_nbsp("mut");
-                    }
+            PatKind::Ident(BindingAnnotation(by_ref, mutbl), ident, ref sub) => {
+                if by_ref == ByRef::Yes {
+                    self.word_nbsp("ref");
+                }
+                if mutbl == Mutability::Mut {
+                    self.word_nbsp("mut");
                 }
                 self.print_ident(ident);
                 if let Some(ref p) = *sub {
@@ -1487,12 +1483,10 @@ impl<'a> State<'a> {
             }
             PatKind::Ref(ref inner, mutbl) => {
                 self.word("&");
-                if mutbl == ast::Mutability::Mut {
+                if mutbl == Mutability::Mut {
                     self.word("mut ");
                 }
-                if let PatKind::Ident(ast::BindingMode::ByValue(ast::Mutability::Mut), ..) =
-                    inner.kind
-                {
+                if let PatKind::Ident(ast::BindingAnnotation::MUT, ..) = inner.kind {
                     self.popen();
                     self.print_pat(inner);
                     self.pclose();
diff --git a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
index dd9590016b9..e2db7f3ead1 100644
--- a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
@@ -367,7 +367,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
 
                 if let Some(Node::Pat(pat)) = self.infcx.tcx.hir().find(upvar_hir_id)
                     && let hir::PatKind::Binding(
-                        hir::BindingAnnotation::Unannotated,
+                        hir::BindingAnnotation::NONE,
                         _,
                         upvar_ident,
                         _,
diff --git a/compiler/rustc_builtin_macros/src/deriving/generic/mod.rs b/compiler/rustc_builtin_macros/src/deriving/generic/mod.rs
index adffebd3fd2..3cc160adb53 100644
--- a/compiler/rustc_builtin_macros/src/deriving/generic/mod.rs
+++ b/compiler/rustc_builtin_macros/src/deriving/generic/mod.rs
@@ -164,7 +164,9 @@ pub use SubstructureFields::*;
 
 use crate::deriving;
 use rustc_ast::ptr::P;
-use rustc_ast::{self as ast, EnumDef, Expr, Generics, PatKind};
+use rustc_ast::{
+    self as ast, BindingAnnotation, ByRef, EnumDef, Expr, Generics, Mutability, PatKind,
+};
 use rustc_ast::{GenericArg, GenericParamKind, VariantData};
 use rustc_attr as attr;
 use rustc_expand::base::{Annotatable, ExtCtxt};
@@ -1063,9 +1065,9 @@ impl<'a> MethodDef<'a> {
             let mut body = mk_body(cx, selflike_fields);
 
             let struct_path = cx.path(span, vec![Ident::new(kw::SelfUpper, type_ident.span)]);
-            let use_ref_pat = is_packed && !always_copy;
+            let by_ref = ByRef::from(is_packed && !always_copy);
             let patterns =
-                trait_.create_struct_patterns(cx, struct_path, struct_def, &prefixes, use_ref_pat);
+                trait_.create_struct_patterns(cx, struct_path, struct_def, &prefixes, by_ref);
 
             // Do the let-destructuring.
             let mut stmts: Vec<_> = iter::zip(selflike_args, patterns)
@@ -1247,13 +1249,13 @@ impl<'a> MethodDef<'a> {
 
                 let sp = variant.span.with_ctxt(trait_.span.ctxt());
                 let variant_path = cx.path(sp, vec![type_ident, variant.ident]);
-                let use_ref_pat = false; // because enums can't be repr(packed)
+                let by_ref = ByRef::No; // because enums can't be repr(packed)
                 let mut subpats: Vec<_> = trait_.create_struct_patterns(
                     cx,
                     variant_path,
                     &variant.data,
                     &prefixes,
-                    use_ref_pat,
+                    by_ref,
                 );
 
                 // `(VariantK, VariantK, ...)` or just `VariantK`.
@@ -1414,7 +1416,7 @@ impl<'a> TraitDef<'a> {
         struct_path: ast::Path,
         struct_def: &'a VariantData,
         prefixes: &[String],
-        use_ref_pat: bool,
+        by_ref: ByRef,
     ) -> Vec<P<ast::Pat>> {
         prefixes
             .iter()
@@ -1422,17 +1424,19 @@ impl<'a> TraitDef<'a> {
                 let pieces_iter =
                     struct_def.fields().iter().enumerate().map(|(i, struct_field)| {
                         let sp = struct_field.span.with_ctxt(self.span.ctxt());
-                        let binding_mode = if use_ref_pat {
-                            ast::BindingMode::ByRef(ast::Mutability::Not)
-                        } else {
-                            ast::BindingMode::ByValue(ast::Mutability::Not)
-                        };
                         let ident = self.mk_pattern_ident(prefix, i);
                         let path = ident.with_span_pos(sp);
                         (
                             sp,
                             struct_field.ident,
-                            cx.pat(path.span, PatKind::Ident(binding_mode, path, None)),
+                            cx.pat(
+                                path.span,
+                                PatKind::Ident(
+                                    BindingAnnotation(by_ref, Mutability::Not),
+                                    path,
+                                    None,
+                                ),
+                            ),
                         )
                     });
 
diff --git a/compiler/rustc_expand/src/build.rs b/compiler/rustc_expand/src/build.rs
index c4890b4a9c4..cf2c023c2f8 100644
--- a/compiler/rustc_expand/src/build.rs
+++ b/compiler/rustc_expand/src/build.rs
@@ -178,8 +178,7 @@ impl<'a> ExtCtxt<'a> {
         ex: P<ast::Expr>,
     ) -> ast::Stmt {
         let pat = if mutbl {
-            let binding_mode = ast::BindingMode::ByValue(ast::Mutability::Mut);
-            self.pat_ident_binding_mode(sp, ident, binding_mode)
+            self.pat_ident_binding_mode(sp, ident, ast::BindingAnnotation::MUT)
         } else {
             self.pat_ident(sp, ident)
         };
@@ -445,17 +444,16 @@ impl<'a> ExtCtxt<'a> {
         self.pat(span, PatKind::Lit(expr))
     }
     pub fn pat_ident(&self, span: Span, ident: Ident) -> P<ast::Pat> {
-        let binding_mode = ast::BindingMode::ByValue(ast::Mutability::Not);
-        self.pat_ident_binding_mode(span, ident, binding_mode)
+        self.pat_ident_binding_mode(span, ident, ast::BindingAnnotation::NONE)
     }
 
     pub fn pat_ident_binding_mode(
         &self,
         span: Span,
         ident: Ident,
-        bm: ast::BindingMode,
+        ann: ast::BindingAnnotation,
     ) -> P<ast::Pat> {
-        let pat = PatKind::Ident(bm, ident.with_span_pos(span), None);
+        let pat = PatKind::Ident(ann, ident.with_span_pos(span), None);
         self.pat(span, pat)
     }
     pub fn pat_path(&self, span: Span, path: ast::Path) -> P<ast::Pat> {
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index a069c49b0cc..34c4f0bc273 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/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::{BorrowKind, ImplPolarity, IsAuto};
+pub use rustc_ast::{BindingAnnotation, BorrowKind, ByRef, ImplPolarity, IsAuto};
 pub use rustc_ast::{CaptureBy, Movability, Mutability};
 use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
 use rustc_data_structures::fingerprint::Fingerprint;
@@ -1049,30 +1049,6 @@ pub struct PatField<'hir> {
     pub span: Span,
 }
 
-/// 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.
-#[derive(Copy, Clone, PartialEq, Encodable, Debug, HashStable_Generic)]
-pub enum BindingAnnotation {
-    /// No binding annotation given: this means that the final binding mode
-    /// will depend on whether we have skipped through a `&` reference
-    /// when matching. For example, the `x` in `Some(x)` will have binding
-    /// mode `None`; if you do `let Some(x) = &Some(22)`, it will
-    /// ultimately be inferred to be by-reference.
-    ///
-    /// Note that implicit reference skipping is not implemented yet (#42640).
-    Unannotated,
-
-    /// Annotated with `mut x` -- could be either ref or not, similar to `None`.
-    Mutable,
-
-    /// Annotated as `ref`, like `ref x`
-    Ref,
-
-    /// Annotated as `ref mut x`.
-    RefMut,
-}
-
 #[derive(Copy, Clone, PartialEq, Encodable, Debug, HashStable_Generic)]
 pub enum RangeEnd {
     Included,
diff --git a/compiler/rustc_hir/src/pat_util.rs b/compiler/rustc_hir/src/pat_util.rs
index 93112199b60..9baaf9390f2 100644
--- a/compiler/rustc_hir/src/pat_util.rs
+++ b/compiler/rustc_hir/src/pat_util.rs
@@ -1,6 +1,6 @@
 use crate::def::{CtorOf, DefKind, Res};
 use crate::def_id::DefId;
-use crate::hir::{self, HirId, PatKind};
+use crate::hir::{self, BindingAnnotation, ByRef, HirId, PatKind};
 use rustc_data_structures::fx::FxHashSet;
 use rustc_span::hygiene::DesugaringKind;
 use rustc_span::symbol::Ident;
@@ -93,12 +93,7 @@ impl hir::Pat<'_> {
 
     pub fn simple_ident(&self) -> Option<Ident> {
         match self.kind {
-            PatKind::Binding(
-                hir::BindingAnnotation::Unannotated | hir::BindingAnnotation::Mutable,
-                _,
-                ident,
-                None,
-            ) => Some(ident),
+            PatKind::Binding(BindingAnnotation(ByRef::No, _), _, ident, None) => Some(ident),
             _ => None,
         }
     }
@@ -135,11 +130,11 @@ impl hir::Pat<'_> {
     pub fn contains_explicit_ref_binding(&self) -> Option<hir::Mutability> {
         let mut result = None;
         self.each_binding(|annotation, _, _, _| match annotation {
-            hir::BindingAnnotation::Ref => match result {
+            hir::BindingAnnotation::REF => match result {
                 None | Some(hir::Mutability::Not) => result = Some(hir::Mutability::Not),
                 _ => {}
             },
-            hir::BindingAnnotation::RefMut => result = Some(hir::Mutability::Mut),
+            hir::BindingAnnotation::REF_MUT => result = Some(hir::Mutability::Mut),
             _ => {}
         });
         result
diff --git a/compiler/rustc_hir_pretty/src/lib.rs b/compiler/rustc_hir_pretty/src/lib.rs
index 42663da8a3f..bb83b371ae8 100644
--- a/compiler/rustc_hir_pretty/src/lib.rs
+++ b/compiler/rustc_hir_pretty/src/lib.rs
@@ -9,7 +9,9 @@ use rustc_ast_pretty::pp::{self, Breaks};
 use rustc_ast_pretty::pprust::{Comments, PrintState};
 use rustc_hir as hir;
 use rustc_hir::LifetimeParamKind;
-use rustc_hir::{GenericArg, GenericParam, GenericParamKind, Node, Term};
+use rustc_hir::{
+    BindingAnnotation, ByRef, GenericArg, GenericParam, GenericParamKind, Mutability, Node, Term,
+};
 use rustc_hir::{GenericBound, PatKind, RangeEnd, TraitBoundModifier};
 use rustc_span::source_map::SourceMap;
 use rustc_span::symbol::{kw, Ident, IdentPrinter, Symbol};
@@ -1758,20 +1760,12 @@ impl<'a> State<'a> {
         // is that it doesn't matter
         match pat.kind {
             PatKind::Wild => self.word("_"),
-            PatKind::Binding(binding_mode, _, ident, sub) => {
-                match binding_mode {
-                    hir::BindingAnnotation::Ref => {
-                        self.word_nbsp("ref");
-                        self.print_mutability(hir::Mutability::Not, false);
-                    }
-                    hir::BindingAnnotation::RefMut => {
-                        self.word_nbsp("ref");
-                        self.print_mutability(hir::Mutability::Mut, false);
-                    }
-                    hir::BindingAnnotation::Unannotated => {}
-                    hir::BindingAnnotation::Mutable => {
-                        self.word_nbsp("mut");
-                    }
+            PatKind::Binding(BindingAnnotation(by_ref, mutbl), _, ident, sub) => {
+                if by_ref == ByRef::Yes {
+                    self.word_nbsp("ref");
+                }
+                if mutbl == Mutability::Mut {
+                    self.word_nbsp("mut");
                 }
                 self.print_ident(ident);
                 if let Some(p) = sub {
diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index 4e9c209a584..6bd5ca7b606 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -259,17 +259,8 @@ impl<'tcx> LateLintPass<'tcx> for NonShorthandFieldPatterns {
                         == Some(cx.tcx.field_index(fieldpat.hir_id, cx.typeck_results()))
                     {
                         cx.struct_span_lint(NON_SHORTHAND_FIELD_PATTERNS, fieldpat.span, |lint| {
-                            let binding = match binding_annot {
-                                hir::BindingAnnotation::Unannotated => None,
-                                hir::BindingAnnotation::Mutable => Some("mut"),
-                                hir::BindingAnnotation::Ref => Some("ref"),
-                                hir::BindingAnnotation::RefMut => Some("ref mut"),
-                            };
-                            let suggested_ident = if let Some(binding) = binding {
-                                format!("{} {}", binding, ident)
-                            } else {
-                                ident.to_string()
-                            };
+                            let suggested_ident =
+                                format!("{}{}", binding_annot.prefix_str(), ident);
                             lint.build(fluent::lint::builtin_non_shorthand_field_patterns)
                                 .set_arg("ident", ident.clone())
                                 .span_suggestion(
diff --git a/compiler/rustc_lint/src/unused.rs b/compiler/rustc_lint/src/unused.rs
index 1f4e5b48091..9a7d722c05a 100644
--- a/compiler/rustc_lint/src/unused.rs
+++ b/compiler/rustc_lint/src/unused.rs
@@ -751,7 +751,7 @@ impl UnusedParens {
         avoid_or: bool,
         avoid_mut: bool,
     ) {
-        use ast::{BindingMode, Mutability, PatKind};
+        use ast::{BindingAnnotation, PatKind};
 
         if let PatKind::Paren(inner) = &value.kind {
             match inner.kind {
@@ -763,7 +763,9 @@ impl UnusedParens {
                 // Avoid `p0 | .. | pn` if we should.
                 PatKind::Or(..) if avoid_or => return,
                 // Avoid `mut x` and `mut x @ p` if we should:
-                PatKind::Ident(BindingMode::ByValue(Mutability::Mut), ..) if avoid_mut => return,
+                PatKind::Ident(BindingAnnotation::MUT, ..) if avoid_mut => {
+                    return;
+                }
                 // Otherwise proceed with linting.
                 _ => {}
             }
diff --git a/compiler/rustc_middle/src/ty/binding.rs b/compiler/rustc_middle/src/ty/binding.rs
index 3d65429f2e5..a5b05a4f9b5 100644
--- a/compiler/rustc_middle/src/ty/binding.rs
+++ b/compiler/rustc_middle/src/ty/binding.rs
@@ -1,6 +1,4 @@
-use rustc_hir::BindingAnnotation;
-use rustc_hir::BindingAnnotation::*;
-use rustc_hir::Mutability;
+use rustc_hir::{BindingAnnotation, ByRef, Mutability};
 
 #[derive(Clone, PartialEq, TyEncodable, TyDecodable, Debug, Copy, HashStable)]
 pub enum BindingMode {
@@ -11,12 +9,10 @@ pub enum BindingMode {
 TrivialTypeTraversalAndLiftImpls! { BindingMode, }
 
 impl BindingMode {
-    pub fn convert(ba: BindingAnnotation) -> BindingMode {
-        match ba {
-            Unannotated => BindingMode::BindByValue(Mutability::Not),
-            Mutable => BindingMode::BindByValue(Mutability::Mut),
-            Ref => BindingMode::BindByReference(Mutability::Not),
-            RefMut => BindingMode::BindByReference(Mutability::Mut),
+    pub fn convert(BindingAnnotation(by_ref, mutbl): BindingAnnotation) -> BindingMode {
+        match by_ref {
+            ByRef::No => BindingMode::BindByValue(mutbl),
+            ByRef::Yes => BindingMode::BindByReference(mutbl),
         }
     }
 }
diff --git a/compiler/rustc_parse/src/parser/diagnostics.rs b/compiler/rustc_parse/src/parser/diagnostics.rs
index dd806e2130e..9b5dd09372c 100644
--- a/compiler/rustc_parse/src/parser/diagnostics.rs
+++ b/compiler/rustc_parse/src/parser/diagnostics.rs
@@ -10,9 +10,9 @@ use rustc_ast::ptr::P;
 use rustc_ast::token::{self, Delimiter, Lit, LitKind, TokenKind};
 use rustc_ast::util::parser::AssocOp;
 use rustc_ast::{
-    AngleBracketedArg, AngleBracketedArgs, AnonConst, AttrVec, BinOpKind, BindingMode, Block,
-    BlockCheckMode, Expr, ExprKind, GenericArg, Generics, Item, ItemKind, Mutability, Param, Pat,
-    PatKind, Path, PathSegment, QSelf, Ty, TyKind,
+    AngleBracketedArg, AngleBracketedArgs, AnonConst, AttrVec, BinOpKind, BindingAnnotation, Block,
+    BlockCheckMode, Expr, ExprKind, GenericArg, Generics, Item, ItemKind, Param, Pat, PatKind,
+    Path, PathSegment, QSelf, Ty, TyKind,
 };
 use rustc_ast_pretty::pprust;
 use rustc_data_structures::fx::FxHashSet;
@@ -37,7 +37,7 @@ const TURBOFISH_SUGGESTION_STR: &str =
 pub(super) fn dummy_arg(ident: Ident) -> Param {
     let pat = P(Pat {
         id: ast::DUMMY_NODE_ID,
-        kind: PatKind::Ident(BindingMode::ByValue(Mutability::Not), ident, None),
+        kind: PatKind::Ident(BindingAnnotation::NONE, ident, None),
         span: ident.span,
         tokens: None,
     });
@@ -2961,7 +2961,7 @@ impl<'a> Parser<'a> {
                                 }
                                 _ => {}
                             },
-                            PatKind::Ident(BindingMode::ByValue(Mutability::Not), ident, None) => {
+                            PatKind::Ident(BindingAnnotation::NONE, ident, None) => {
                                 match &first_pat.kind {
                                     PatKind::Ident(_, old_ident, _) => {
                                         let path = PatKind::Path(
diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs
index 5b75d1d5f22..dbdd85ea8e8 100644
--- a/compiler/rustc_parse/src/parser/item.rs
+++ b/compiler/rustc_parse/src/parser/item.rs
@@ -8,7 +8,7 @@ use rustc_ast::token::{self, Delimiter, TokenKind};
 use rustc_ast::tokenstream::{DelimSpan, TokenStream, TokenTree};
 use rustc_ast::{self as ast, AttrVec, Attribute, DUMMY_NODE_ID};
 use rustc_ast::{Async, Const, Defaultness, IsAuto, Mutability, Unsafe, UseTree, UseTreeKind};
-use rustc_ast::{BindingMode, Block, FnDecl, FnSig, Param, SelfKind};
+use rustc_ast::{BindingAnnotation, Block, FnDecl, FnSig, Param, SelfKind};
 use rustc_ast::{EnumDef, FieldDef, Generics, TraitRef, Ty, TyKind, Variant, VariantData};
 use rustc_ast::{FnHeader, ForeignItem, Path, PathSegment, Visibility, VisibilityKind};
 use rustc_ast::{MacArgs, MacCall, MacDelimiter};
@@ -2322,7 +2322,7 @@ impl<'a> Parser<'a> {
                 match ty {
                     Ok(ty) => {
                         let ident = Ident::new(kw::Empty, this.prev_token.span);
-                        let bm = BindingMode::ByValue(Mutability::Not);
+                        let bm = BindingAnnotation::NONE;
                         let pat = this.mk_pat_ident(ty.span, bm, ident);
                         (pat, ty)
                     }
diff --git a/compiler/rustc_parse/src/parser/pat.rs b/compiler/rustc_parse/src/parser/pat.rs
index 8b3200d45fc..88bd57d37cb 100644
--- a/compiler/rustc_parse/src/parser/pat.rs
+++ b/compiler/rustc_parse/src/parser/pat.rs
@@ -4,8 +4,8 @@ use rustc_ast::mut_visit::{noop_visit_pat, MutVisitor};
 use rustc_ast::ptr::P;
 use rustc_ast::token::{self, Delimiter};
 use rustc_ast::{
-    self as ast, AttrVec, BindingMode, Expr, ExprKind, MacCall, Mutability, Pat, PatField, PatKind,
-    Path, QSelf, RangeEnd, RangeSyntax,
+    self as ast, AttrVec, BindingAnnotation, ByRef, Expr, ExprKind, MacCall, Mutability, Pat,
+    PatField, PatKind, Path, QSelf, RangeEnd, RangeSyntax,
 };
 use rustc_ast_pretty::pprust;
 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder, ErrorGuaranteed, PResult};
@@ -353,7 +353,7 @@ impl<'a> Parser<'a> {
         } else if self.eat_keyword(kw::Ref) {
             // Parse ref ident @ pat / ref mut ident @ pat
             let mutbl = self.parse_mutability();
-            self.parse_pat_ident(BindingMode::ByRef(mutbl))?
+            self.parse_pat_ident(BindingAnnotation(ByRef::Yes, mutbl))?
         } else if self.eat_keyword(kw::Box) {
             self.parse_pat_box()?
         } else if self.check_inline_const(0) {
@@ -369,7 +369,7 @@ impl<'a> Parser<'a> {
             // Parse `ident @ pat`
             // This can give false positives and parse nullary enums,
             // they are dealt with later in resolve.
-            self.parse_pat_ident(BindingMode::ByValue(Mutability::Not))?
+            self.parse_pat_ident(BindingAnnotation::NONE)?
         } else if self.is_start_of_pat_with_path() {
             // Parse pattern starting with a path
             let (qself, path) = if self.eat_lt() {
@@ -578,7 +578,8 @@ impl<'a> Parser<'a> {
         let mut pat = self.parse_pat_no_top_alt(Some("identifier"))?;
 
         // If we don't have `mut $ident (@ pat)?`, error.
-        if let PatKind::Ident(BindingMode::ByValue(m @ Mutability::Not), ..) = &mut pat.kind {
+        if let PatKind::Ident(BindingAnnotation(ByRef::No, m @ Mutability::Not), ..) = &mut pat.kind
+        {
             // Don't recurse into the subpattern.
             // `mut` on the outer binding doesn't affect the inner bindings.
             *m = Mutability::Mut;
@@ -604,7 +605,7 @@ impl<'a> Parser<'a> {
             )
             .emit();
 
-        self.parse_pat_ident(BindingMode::ByRef(Mutability::Mut))
+        self.parse_pat_ident(BindingAnnotation::REF_MUT)
     }
 
     /// Turn all by-value immutable bindings in a pattern into mutable bindings.
@@ -613,7 +614,8 @@ impl<'a> Parser<'a> {
         struct AddMut(bool);
         impl MutVisitor for AddMut {
             fn visit_pat(&mut self, pat: &mut P<Pat>) {
-                if let PatKind::Ident(BindingMode::ByValue(m @ Mutability::Not), ..) = &mut pat.kind
+                if let PatKind::Ident(BindingAnnotation(ByRef::No, m @ Mutability::Not), ..) =
+                    &mut pat.kind
                 {
                     self.0 = true;
                     *m = Mutability::Mut;
@@ -838,7 +840,7 @@ impl<'a> Parser<'a> {
     /// Parses `ident` or `ident @ pat`.
     /// Used by the copy foo and ref foo patterns to give a good
     /// error message when parsing mistakes like `ref foo(a, b)`.
-    fn parse_pat_ident(&mut self, binding_mode: BindingMode) -> PResult<'a, PatKind> {
+    fn parse_pat_ident(&mut self, binding_annotation: BindingAnnotation) -> PResult<'a, PatKind> {
         let ident = self.parse_ident()?;
         let sub = if self.eat(&token::At) {
             Some(self.parse_pat_no_top_alt(Some("binding pattern"))?)
@@ -856,7 +858,7 @@ impl<'a> Parser<'a> {
                 .struct_span_err(self.prev_token.span, "expected identifier, found enum pattern"));
         }
 
-        Ok(PatKind::Ident(binding_mode, ident, sub))
+        Ok(PatKind::Ident(binding_annotation, ident, sub))
     }
 
     /// Parse a struct ("record") pattern (e.g. `Foo { ... }` or `Foo::Bar { ... }`).
@@ -936,11 +938,7 @@ impl<'a> Parser<'a> {
                 None
             };
 
-            Ok(PatKind::Ident(
-                BindingMode::ByValue(Mutability::Not),
-                Ident::new(kw::Box, box_span),
-                sub,
-            ))
+            Ok(PatKind::Ident(BindingAnnotation::NONE, Ident::new(kw::Box, box_span), sub))
         } else {
             let pat = self.parse_pat_with_range_pat(false, None)?;
             self.sess.gated_spans.gate(sym::box_patterns, box_span.to(self.prev_token.span));
@@ -1117,14 +1115,12 @@ impl<'a> Parser<'a> {
             let fieldname = self.parse_field_name()?;
             hi = self.prev_token.span;
 
-            let bind_type = match (is_ref, is_mut) {
-                (true, true) => BindingMode::ByRef(Mutability::Mut),
-                (true, false) => BindingMode::ByRef(Mutability::Not),
-                (false, true) => BindingMode::ByValue(Mutability::Mut),
-                (false, false) => BindingMode::ByValue(Mutability::Not),
+            let mutability = match is_mut {
+                false => Mutability::Not,
+                true => Mutability::Mut,
             };
-
-            let fieldpat = self.mk_pat_ident(boxed_span.to(hi), bind_type, fieldname);
+            let ann = BindingAnnotation(ByRef::from(is_ref), mutability);
+            let fieldpat = self.mk_pat_ident(boxed_span.to(hi), ann, fieldname);
             let subpat =
                 if is_box { self.mk_pat(lo.to(hi), PatKind::Box(fieldpat)) } else { fieldpat };
             (subpat, fieldname, true)
@@ -1141,8 +1137,8 @@ impl<'a> Parser<'a> {
         })
     }
 
-    pub(super) fn mk_pat_ident(&self, span: Span, bm: BindingMode, ident: Ident) -> P<Pat> {
-        self.mk_pat(span, PatKind::Ident(bm, ident, None))
+    pub(super) fn mk_pat_ident(&self, span: Span, ann: BindingAnnotation, ident: Ident) -> P<Pat> {
+        self.mk_pat(span, PatKind::Ident(ann, ident, None))
     }
 
     pub(super) fn mk_pat(&self, span: Span, kind: PatKind) -> P<Pat> {
diff --git a/compiler/rustc_passes/src/naked_functions.rs b/compiler/rustc_passes/src/naked_functions.rs
index 296b6ed5d99..607973446fc 100644
--- a/compiler/rustc_passes/src/naked_functions.rs
+++ b/compiler/rustc_passes/src/naked_functions.rs
@@ -76,7 +76,7 @@ fn check_no_patterns(tcx: TyCtxt<'_>, params: &[hir::Param<'_>]) {
     for param in params {
         match param.pat.kind {
             hir::PatKind::Wild
-            | hir::PatKind::Binding(hir::BindingAnnotation::Unannotated, _, _, None) => {}
+            | hir::PatKind::Binding(hir::BindingAnnotation::NONE, _, _, None) => {}
             _ => {
                 tcx.sess
                     .struct_span_err(
diff --git a/compiler/rustc_resolve/src/late.rs b/compiler/rustc_resolve/src/late.rs
index dbe4d691f04..b37feb15890 100644
--- a/compiler/rustc_resolve/src/late.rs
+++ b/compiler/rustc_resolve/src/late.rs
@@ -20,7 +20,7 @@ use rustc_errors::DiagnosticId;
 use rustc_hir::def::Namespace::{self, *};
 use rustc_hir::def::{self, CtorKind, DefKind, LifetimeRes, PartialRes, PerNS};
 use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID};
-use rustc_hir::{PrimTy, TraitCandidate};
+use rustc_hir::{BindingAnnotation, PrimTy, TraitCandidate};
 use rustc_middle::middle::resolve_lifetime::Set1;
 use rustc_middle::ty::DefIdTree;
 use rustc_middle::{bug, span_bug};
@@ -50,7 +50,7 @@ use diagnostics::{
 #[derive(Copy, Clone, Debug)]
 struct BindingInfo {
     span: Span,
-    binding_mode: BindingMode,
+    annotation: BindingAnnotation,
 }
 
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
@@ -2865,10 +2865,10 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
 
         pat.walk(&mut |pat| {
             match pat.kind {
-                PatKind::Ident(binding_mode, ident, ref sub_pat)
+                PatKind::Ident(annotation, ident, ref sub_pat)
                     if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
                 {
-                    binding_map.insert(ident, BindingInfo { span: ident.span, binding_mode });
+                    binding_map.insert(ident, BindingInfo { span: ident.span, annotation });
                 }
                 PatKind::Or(ref ps) => {
                     // Check the consistency of this or-pattern and
@@ -2925,7 +2925,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
                         binding_error.target.insert(pat_outer.span);
                     }
                     Some(binding_outer) => {
-                        if binding_outer.binding_mode != binding_inner.binding_mode {
+                        if binding_outer.annotation != binding_inner.annotation {
                             // The binding modes in the outer and inner bindings differ.
                             inconsistent_vars
                                 .entry(name)
@@ -3146,14 +3146,14 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
     fn try_resolve_as_non_binding(
         &mut self,
         pat_src: PatternSource,
-        bm: BindingMode,
+        ann: BindingAnnotation,
         ident: Ident,
         has_sub: bool,
     ) -> Option<Res> {
         // An immutable (no `mut`) by-value (no `ref`) binding pattern without
         // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
         // also be interpreted as a path to e.g. a constant, variant, etc.
-        let is_syntactic_ambiguity = !has_sub && bm == BindingMode::ByValue(Mutability::Not);
+        let is_syntactic_ambiguity = !has_sub && ann == BindingAnnotation::NONE;
 
         let ls_binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS)?;
         let (res, binding) = match ls_binding {
diff --git a/compiler/rustc_save_analysis/src/lib.rs b/compiler/rustc_save_analysis/src/lib.rs
index 16af5338510..eae1f083107 100644
--- a/compiler/rustc_save_analysis/src/lib.rs
+++ b/compiler/rustc_save_analysis/src/lib.rs
@@ -865,23 +865,12 @@ impl<'l> Visitor<'l> for PathCollector<'l> {
             hir::PatKind::TupleStruct(ref path, ..) | hir::PatKind::Path(ref path) => {
                 self.collected_paths.push((p.hir_id, path));
             }
-            hir::PatKind::Binding(bm, _, ident, _) => {
+            hir::PatKind::Binding(hir::BindingAnnotation(_, mutbl), _, ident, _) => {
                 debug!(
                     "PathCollector, visit ident in pat {}: {:?} {:?}",
                     ident, p.span, ident.span
                 );
-                let immut = match bm {
-                    // Even if the ref is mut, you can't change the ref, only
-                    // the data pointed at, so showing the initialising expression
-                    // is still worthwhile.
-                    hir::BindingAnnotation::Unannotated | hir::BindingAnnotation::Ref => {
-                        hir::Mutability::Not
-                    }
-                    hir::BindingAnnotation::Mutable | hir::BindingAnnotation::RefMut => {
-                        hir::Mutability::Mut
-                    }
-                };
-                self.collected_idents.push((p.hir_id, ident, immut));
+                self.collected_idents.push((p.hir_id, ident, mutbl));
             }
             _ => {}
         }
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
index 02adae5bde1..b012073f771 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -774,7 +774,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
             // Get the local name of this closure. This can be inaccurate because
             // of the possibility of reassignment, but this should be good enough.
             match &kind {
-                hir::PatKind::Binding(hir::BindingAnnotation::Unannotated, _, ident, None) => {
+                hir::PatKind::Binding(hir::BindingAnnotation::NONE, _, ident, None) => {
                     Some(ident.name)
                 }
                 _ => {
diff --git a/compiler/rustc_typeck/src/check/pat.rs b/compiler/rustc_typeck/src/check/pat.rs
index 6dcc364bb50..9096fc442d4 100644
--- a/compiler/rustc_typeck/src/check/pat.rs
+++ b/compiler/rustc_typeck/src/check/pat.rs
@@ -569,7 +569,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     ) -> Ty<'tcx> {
         // Determine the binding mode...
         let bm = match ba {
-            hir::BindingAnnotation::Unannotated => def_bm,
+            hir::BindingAnnotation::NONE => def_bm,
             _ => BindingMode::convert(ba),
         };
         // ...and store it in a side table:
@@ -655,7 +655,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         ba: hir::BindingAnnotation,
     ) {
         match (expected.kind(), actual.kind(), ba) {
-            (ty::Ref(_, inner_ty, _), _, hir::BindingAnnotation::Unannotated)
+            (ty::Ref(_, inner_ty, _), _, hir::BindingAnnotation::NONE)
                 if self.can_eq(self.param_env, *inner_ty, actual).is_ok() =>
             {
                 err.span_suggestion_verbose(
@@ -665,7 +665,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     Applicability::MaybeIncorrect,
                 );
             }
-            (_, ty::Ref(_, inner_ty, _), hir::BindingAnnotation::Ref)
+            (_, ty::Ref(_, inner_ty, _), hir::BindingAnnotation::REF)
                 if self.can_eq(self.param_env, expected, *inner_ty).is_ok() =>
             {
                 err.span_suggestion_verbose(
diff --git a/compiler/rustc_typeck/src/check/region.rs b/compiler/rustc_typeck/src/check/region.rs
index 0081e9049ee..b779713482e 100644
--- a/compiler/rustc_typeck/src/check/region.rs
+++ b/compiler/rustc_typeck/src/check/region.rs
@@ -587,8 +587,7 @@ fn resolve_local<'tcx>(
         // & expression, and its lifetime would be extended to the end of the block (due
         // to a different rule, not the below code).
         match pat.kind {
-            PatKind::Binding(hir::BindingAnnotation::Ref, ..)
-            | PatKind::Binding(hir::BindingAnnotation::RefMut, ..) => true,
+            PatKind::Binding(hir::BindingAnnotation(hir::ByRef::Yes, _), ..) => true,
 
             PatKind::Struct(_, ref field_pats, _) => {
                 field_pats.iter().any(|fp| is_binding_pat(&fp.pat))
@@ -607,10 +606,7 @@ fn resolve_local<'tcx>(
             PatKind::Box(ref subpat) => is_binding_pat(&subpat),
 
             PatKind::Ref(_, _)
-            | PatKind::Binding(
-                hir::BindingAnnotation::Unannotated | hir::BindingAnnotation::Mutable,
-                ..,
-            )
+            | PatKind::Binding(hir::BindingAnnotation(hir::ByRef::No, _), ..)
             | PatKind::Wild
             | PatKind::Path(_)
             | PatKind::Lit(_)