Auto merge of #83188 - petrochenkov:field, r=lcnr

ast/hir: Rename field-related structures

I always forget what `ast::Field` and `ast::StructField` mean despite working with AST for long time, so this PR changes the naming to less confusing and more consistent.

- `StructField` -> `FieldDef` ("field definition")
- `Field` -> `ExprField` ("expression field", not "field expression")
- `FieldPat` -> `PatField` ("pattern field", not "field pattern")

Various visiting and other methods working with the fields are renamed correspondingly too.

The second commit reduces the size of `ExprKind` by boxing fields of `ExprKind::Struct` in preparation for https://github.com/rust-lang/rust/pull/80080.

4 files changed, 66 insertions, 56 deletions

diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs
index 005ac8e4521..ee7367d408d 100644
--- a/compiler/rustc_ast/src/ast.rs
+++ b/compiler/rustc_ast/src/ast.rs
@@ -655,7 +655,7 @@ impl Pat {
 /// are treated the same as `x: x, y: ref y, z: ref mut z`,
 /// except when `is_shorthand` is true.
 #[derive(Clone, Encodable, Decodable, Debug)]
-pub struct FieldPat {
+pub struct PatField {
     /// The identifier for the field.
     pub ident: Ident,
     /// The pattern the field is destructured to.
@@ -700,7 +700,7 @@ pub enum PatKind {
 
     /// A struct or struct variant pattern (e.g., `Variant {x, y, ..}`).
     /// The `bool` is `true` in the presence of a `..`.
-    Struct(Path, Vec<FieldPat>, /* recovered */ bool),
+    Struct(Path, Vec<PatField>, /* recovered */ bool),
 
     /// A tuple struct/variant pattern (`Variant(x, y, .., z)`).
     TupleStruct(Path, Vec<P<Pat>>),
@@ -1035,9 +1035,9 @@ pub struct Arm {
     pub is_placeholder: bool,
 }
 
-/// Access of a named (e.g., `obj.foo`) or unnamed (e.g., `obj.0`) struct field.
+/// A single field in a struct expression, e.g. `x: value` and `y` in `Foo { x: value, y }`.
 #[derive(Clone, Encodable, Decodable, Debug)]
-pub struct Field {
+pub struct ExprField {
     pub attrs: AttrVec,
     pub id: NodeId,
     pub span: Span,
@@ -1082,7 +1082,7 @@ pub struct Expr {
 
 // `Expr` is used a lot. Make sure it doesn't unintentionally get bigger.
 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-rustc_data_structures::static_assert_size!(Expr, 120);
+rustc_data_structures::static_assert_size!(Expr, 104);
 
 impl Expr {
     /// Returns `true` if this expression would be valid somewhere that expects a value;
@@ -1253,6 +1253,13 @@ pub enum StructRest {
 }
 
 #[derive(Clone, Encodable, Decodable, Debug)]
+pub struct StructExpr {
+    pub path: Path,
+    pub fields: Vec<ExprField>,
+    pub rest: StructRest,
+}
+
+#[derive(Clone, Encodable, Decodable, Debug)]
 pub enum ExprKind {
     /// A `box x` expression.
     Box(P<Expr>),
@@ -1377,7 +1384,7 @@ pub enum ExprKind {
     /// A struct literal expression.
     ///
     /// E.g., `Foo {x: 1, y: 2}`, or `Foo {x: 1, .. rest}`.
-    Struct(Path, Vec<Field>, StructRest),
+    Struct(P<StructExpr>),
 
     /// An array literal constructed from one repeated element.
     ///
@@ -2527,11 +2534,11 @@ impl VisibilityKind {
     }
 }
 
-/// Field of a struct.
+/// Field definition in a struct, variant or union.
 ///
 /// E.g., `bar: usize` as in `struct Foo { bar: usize }`.
 #[derive(Clone, Encodable, Decodable, Debug)]
-pub struct StructField {
+pub struct FieldDef {
     pub attrs: Vec<Attribute>,
     pub id: NodeId,
     pub span: Span,
@@ -2548,11 +2555,11 @@ pub enum VariantData {
     /// Struct variant.
     ///
     /// E.g., `Bar { .. }` as in `enum Foo { Bar { .. } }`.
-    Struct(Vec<StructField>, bool),
+    Struct(Vec<FieldDef>, bool),
     /// Tuple variant.
     ///
     /// E.g., `Bar(..)` as in `enum Foo { Bar(..) }`.
-    Tuple(Vec<StructField>, NodeId),
+    Tuple(Vec<FieldDef>, NodeId),
     /// Unit variant.
     ///
     /// E.g., `Bar = ..` as in `enum Foo { Bar = .. }`.
@@ -2561,7 +2568,7 @@ pub enum VariantData {
 
 impl VariantData {
     /// Return the fields of this variant.
-    pub fn fields(&self) -> &[StructField] {
+    pub fn fields(&self) -> &[FieldDef] {
         match *self {
             VariantData::Struct(ref fields, ..) | VariantData::Tuple(ref fields, _) => fields,
             _ => &[],
diff --git a/compiler/rustc_ast/src/ast_like.rs b/compiler/rustc_ast/src/ast_like.rs
index a71f2ac9815..63bc7c49a99 100644
--- a/compiler/rustc_ast/src/ast_like.rs
+++ b/compiler/rustc_ast/src/ast_like.rs
@@ -1,6 +1,6 @@
 use super::ptr::P;
 use super::tokenstream::LazyTokenStream;
-use super::{Arm, Field, FieldPat, GenericParam, Param, StructField, Variant};
+use super::{Arm, ExprField, FieldDef, GenericParam, Param, PatField, Variant};
 use super::{AssocItem, Expr, ForeignItem, Item, Local};
 use super::{AttrItem, AttrKind, Block, Pat, Path, Ty, Visibility};
 use super::{AttrVec, Attribute, Stmt, StmtKind};
@@ -187,8 +187,7 @@ derive_has_tokens_and_attrs! {
 // These ast nodes only support inert attributes, so they don't
 // store tokens (since nothing can observe them)
 derive_has_attrs_no_tokens! {
-    StructField, Arm,
-    Field, FieldPat, Variant, Param, GenericParam
+    FieldDef, Arm, ExprField, PatField, Variant, Param, GenericParam
 }
 
 // These AST nodes don't support attributes, but can
diff --git a/compiler/rustc_ast/src/mut_visit.rs b/compiler/rustc_ast/src/mut_visit.rs
index c286738811c..f426f2c7fec 100644
--- a/compiler/rustc_ast/src/mut_visit.rs
+++ b/compiler/rustc_ast/src/mut_visit.rs
@@ -102,8 +102,8 @@ pub trait MutVisitor: Sized {
         noop_visit_fn_header(header, self);
     }
 
-    fn flat_map_struct_field(&mut self, sf: StructField) -> SmallVec<[StructField; 1]> {
-        noop_flat_map_struct_field(sf, self)
+    fn flat_map_field_def(&mut self, fd: FieldDef) -> SmallVec<[FieldDef; 1]> {
+        noop_flat_map_field_def(fd, self)
     }
 
     fn visit_item_kind(&mut self, i: &mut ItemKind) {
@@ -254,8 +254,8 @@ pub trait MutVisitor: Sized {
         noop_visit_mt(mt, self);
     }
 
-    fn flat_map_field(&mut self, f: Field) -> SmallVec<[Field; 1]> {
-        noop_flat_map_field(f, self)
+    fn flat_map_expr_field(&mut self, f: ExprField) -> SmallVec<[ExprField; 1]> {
+        noop_flat_map_expr_field(f, self)
     }
 
     fn visit_where_clause(&mut self, where_clause: &mut WhereClause) {
@@ -278,8 +278,8 @@ pub trait MutVisitor: Sized {
         // Do nothing.
     }
 
-    fn flat_map_field_pattern(&mut self, fp: FieldPat) -> SmallVec<[FieldPat; 1]> {
-        noop_flat_map_field_pattern(fp, self)
+    fn flat_map_pat_field(&mut self, fp: PatField) -> SmallVec<[PatField; 1]> {
+        noop_flat_map_pat_field(fp, self)
     }
 }
 
@@ -385,11 +385,11 @@ pub fn visit_delim_span<T: MutVisitor>(dspan: &mut DelimSpan, vis: &mut T) {
     vis.visit_span(&mut dspan.close);
 }
 
-pub fn noop_flat_map_field_pattern<T: MutVisitor>(
-    mut fp: FieldPat,
+pub fn noop_flat_map_pat_field<T: MutVisitor>(
+    mut fp: PatField,
     vis: &mut T,
-) -> SmallVec<[FieldPat; 1]> {
-    let FieldPat { attrs, id, ident, is_placeholder: _, is_shorthand: _, pat, span } = &mut fp;
+) -> SmallVec<[PatField; 1]> {
+    let PatField { attrs, id, ident, is_placeholder: _, is_shorthand: _, pat, span } = &mut fp;
     vis.visit_id(id);
     vis.visit_ident(ident);
     vis.visit_pat(pat);
@@ -842,10 +842,10 @@ pub fn noop_visit_where_predicate<T: MutVisitor>(pred: &mut WherePredicate, vis:
 pub fn noop_visit_variant_data<T: MutVisitor>(vdata: &mut VariantData, vis: &mut T) {
     match vdata {
         VariantData::Struct(fields, ..) => {
-            fields.flat_map_in_place(|field| vis.flat_map_struct_field(field));
+            fields.flat_map_in_place(|field| vis.flat_map_field_def(field));
         }
         VariantData::Tuple(fields, id) => {
-            fields.flat_map_in_place(|field| vis.flat_map_struct_field(field));
+            fields.flat_map_in_place(|field| vis.flat_map_field_def(field));
             vis.visit_id(id);
         }
         VariantData::Unit(id) => vis.visit_id(id),
@@ -864,22 +864,25 @@ pub fn noop_visit_poly_trait_ref<T: MutVisitor>(p: &mut PolyTraitRef, vis: &mut
     vis.visit_span(span);
 }
 
-pub fn noop_flat_map_struct_field<T: MutVisitor>(
-    mut sf: StructField,
+pub fn noop_flat_map_field_def<T: MutVisitor>(
+    mut fd: FieldDef,
     visitor: &mut T,
-) -> SmallVec<[StructField; 1]> {
-    let StructField { span, ident, vis, id, ty, attrs, is_placeholder: _ } = &mut sf;
+) -> SmallVec<[FieldDef; 1]> {
+    let FieldDef { span, ident, vis, id, ty, attrs, is_placeholder: _ } = &mut fd;
     visitor.visit_span(span);
     visit_opt(ident, |ident| visitor.visit_ident(ident));
     visitor.visit_vis(vis);
     visitor.visit_id(id);
     visitor.visit_ty(ty);
     visit_attrs(attrs, visitor);
-    smallvec![sf]
+    smallvec![fd]
 }
 
-pub fn noop_flat_map_field<T: MutVisitor>(mut f: Field, vis: &mut T) -> SmallVec<[Field; 1]> {
-    let Field { ident, expr, span, is_shorthand: _, attrs, id, is_placeholder: _ } = &mut f;
+pub fn noop_flat_map_expr_field<T: MutVisitor>(
+    mut f: ExprField,
+    vis: &mut T,
+) -> SmallVec<[ExprField; 1]> {
+    let ExprField { ident, expr, span, is_shorthand: _, attrs, id, is_placeholder: _ } = &mut f;
     vis.visit_ident(ident);
     vis.visit_expr(expr);
     vis.visit_id(id);
@@ -1102,7 +1105,7 @@ pub fn noop_visit_pat<T: MutVisitor>(pat: &mut P<Pat>, vis: &mut T) {
         }
         PatKind::Struct(path, fields, _etc) => {
             vis.visit_path(path);
-            fields.flat_map_in_place(|field| vis.flat_map_field_pattern(field));
+            fields.flat_map_in_place(|field| vis.flat_map_pat_field(field));
         }
         PatKind::Box(inner) => vis.visit_pat(inner),
         PatKind::Ref(inner, _mutbl) => vis.visit_pat(inner),
@@ -1283,10 +1286,11 @@ pub fn noop_visit_expr<T: MutVisitor>(
             visit_vec(inputs, |(_c, expr)| vis.visit_expr(expr));
         }
         ExprKind::MacCall(mac) => vis.visit_mac_call(mac),
-        ExprKind::Struct(path, fields, expr) => {
+        ExprKind::Struct(se) => {
+            let StructExpr { path, fields, rest } = se.deref_mut();
             vis.visit_path(path);
-            fields.flat_map_in_place(|field| vis.flat_map_field(field));
-            match expr {
+            fields.flat_map_in_place(|field| vis.flat_map_expr_field(field));
+            match rest {
                 StructRest::Base(expr) => vis.visit_expr(expr),
                 StructRest::Rest(_span) => {}
                 StructRest::None => {}
diff --git a/compiler/rustc_ast/src/visit.rs b/compiler/rustc_ast/src/visit.rs
index 32b9dd46bae..b1ad29e4ad8 100644
--- a/compiler/rustc_ast/src/visit.rs
+++ b/compiler/rustc_ast/src/visit.rs
@@ -151,8 +151,8 @@ pub trait Visitor<'ast>: Sized {
     fn visit_variant_data(&mut self, s: &'ast VariantData) {
         walk_struct_def(self, s)
     }
-    fn visit_struct_field(&mut self, s: &'ast StructField) {
-        walk_struct_field(self, s)
+    fn visit_field_def(&mut self, s: &'ast FieldDef) {
+        walk_field_def(self, s)
     }
     fn visit_enum_def(
         &mut self,
@@ -208,11 +208,11 @@ pub trait Visitor<'ast>: Sized {
     fn visit_fn_header(&mut self, _header: &'ast FnHeader) {
         // Nothing to do
     }
-    fn visit_field(&mut self, f: &'ast Field) {
-        walk_field(self, f)
+    fn visit_expr_field(&mut self, f: &'ast ExprField) {
+        walk_expr_field(self, f)
     }
-    fn visit_field_pattern(&mut self, fp: &'ast FieldPat) {
-        walk_field_pattern(self, fp)
+    fn visit_pat_field(&mut self, fp: &'ast PatField) {
+        walk_pat_field(self, fp)
     }
 }
 
@@ -364,13 +364,13 @@ where
     walk_list!(visitor, visit_attribute, &variant.attrs);
 }
 
-pub fn walk_field<'a, V: Visitor<'a>>(visitor: &mut V, f: &'a Field) {
+pub fn walk_expr_field<'a, V: Visitor<'a>>(visitor: &mut V, f: &'a ExprField) {
     visitor.visit_expr(&f.expr);
     visitor.visit_ident(f.ident);
     walk_list!(visitor, visit_attribute, f.attrs.iter());
 }
 
-pub fn walk_field_pattern<'a, V: Visitor<'a>>(visitor: &mut V, fp: &'a FieldPat) {
+pub fn walk_pat_field<'a, V: Visitor<'a>>(visitor: &mut V, fp: &'a PatField) {
     visitor.visit_ident(fp.ident);
     visitor.visit_pat(&fp.pat);
     walk_list!(visitor, visit_attribute, fp.attrs.iter());
@@ -509,7 +509,7 @@ pub fn walk_pat<'a, V: Visitor<'a>>(visitor: &mut V, pattern: &'a Pat) {
         }
         PatKind::Struct(ref path, ref fields, _) => {
             visitor.visit_path(path, pattern.id);
-            walk_list!(visitor, visit_field_pattern, fields);
+            walk_list!(visitor, visit_pat_field, fields);
         }
         PatKind::Box(ref subpattern)
         | PatKind::Ref(ref subpattern, _)
@@ -668,16 +668,16 @@ pub fn walk_assoc_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a AssocItem,
 }
 
 pub fn walk_struct_def<'a, V: Visitor<'a>>(visitor: &mut V, struct_definition: &'a VariantData) {
-    walk_list!(visitor, visit_struct_field, struct_definition.fields());
+    walk_list!(visitor, visit_field_def, struct_definition.fields());
 }
 
-pub fn walk_struct_field<'a, V: Visitor<'a>>(visitor: &mut V, struct_field: &'a StructField) {
-    visitor.visit_vis(&struct_field.vis);
-    if let Some(ident) = struct_field.ident {
+pub fn walk_field_def<'a, V: Visitor<'a>>(visitor: &mut V, field: &'a FieldDef) {
+    visitor.visit_vis(&field.vis);
+    if let Some(ident) = field.ident {
         visitor.visit_ident(ident);
     }
-    visitor.visit_ty(&struct_field.ty);
-    walk_list!(visitor, visit_attribute, &struct_field.attrs);
+    visitor.visit_ty(&field.ty);
+    walk_list!(visitor, visit_attribute, &field.attrs);
 }
 
 pub fn walk_block<'a, V: Visitor<'a>>(visitor: &mut V, block: &'a Block) {
@@ -721,10 +721,10 @@ pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) {
             visitor.visit_expr(element);
             visitor.visit_anon_const(count)
         }
-        ExprKind::Struct(ref path, ref fields, ref optional_base) => {
-            visitor.visit_path(path, expression.id);
-            walk_list!(visitor, visit_field, fields);
-            match optional_base {
+        ExprKind::Struct(ref se) => {
+            visitor.visit_path(&se.path, expression.id);
+            walk_list!(visitor, visit_expr_field, &se.fields);
+            match &se.rest {
                 StructRest::Base(expr) => visitor.visit_expr(expr),
                 StructRest::Rest(_span) => {}
                 StructRest::None => {}