Remove anon struct and union types

Author: compiler-errors

compiler/rustc_ast/src/ast.rs

@@ -2167,10 +2167,6 @@ pub enum TyKind {
     Never,
     /// A tuple (`(A, B, C, D,...)`).
     Tup(ThinVec<P<Ty>>),
-    /// An anonymous struct type i.e. `struct { foo: Type }`.
-    AnonStruct(NodeId, ThinVec<FieldDef>),
-    /// An anonymous union type i.e. `union { bar: Type }`.
-    AnonUnion(NodeId, ThinVec<FieldDef>),
     /// A path (`module::module::...::Type`), optionally
     /// "qualified", e.g., `<Vec<T> as SomeTrait>::SomeType`.
     ///
@@ -2227,10 +2223,6 @@ impl TyKind {
             None
         }
     }
-
-    pub fn is_anon_adt(&self) -> bool {
-        matches!(self, TyKind::AnonStruct(..) | TyKind::AnonUnion(..))
-    }
 }
 
 /// Syntax used to declare a trait object.

compiler/rustc_ast/src/mut_visit.rs

@@ -519,10 +519,6 @@ pub fn walk_ty<T: MutVisitor>(vis: &mut T, ty: &mut P<Ty>) {
             visit_vec(bounds, |bound| vis.visit_param_bound(bound, BoundKind::Impl));
         }
         TyKind::MacCall(mac) => vis.visit_mac_call(mac),
-        TyKind::AnonStruct(id, fields) | TyKind::AnonUnion(id, fields) => {
-            vis.visit_id(id);
-            fields.flat_map_in_place(|field| vis.flat_map_field_def(field));
-        }
     }
     visit_lazy_tts(vis, tokens);
     vis.visit_span(span);

compiler/rustc_ast/src/util/classify.rs

@@ -287,12 +287,6 @@ fn type_trailing_braced_mac_call(mut ty: &ast::Ty) -> Option<&ast::MacCall> {
             | ast::TyKind::Pat(..)
             | ast::TyKind::Dummy
             | ast::TyKind::Err(..) => break None,
-
-            // These end in brace, but cannot occur in a let-else statement.
-            // They are only parsed as fields of a data structure. For the
-            // purpose of denying trailing braces in the expression of a
-            // let-else, we can disregard these.
-            ast::TyKind::AnonStruct(..) | ast::TyKind::AnonUnion(..) => break None,
         }
     }
 }

compiler/rustc_ast/src/visit.rs

@@ -535,9 +535,6 @@ pub fn walk_ty<'a, V: Visitor<'a>>(visitor: &mut V, typ: &'a Ty) -> V::Result {
         TyKind::Err(_guar) => {}
         TyKind::MacCall(mac) => try_visit!(visitor.visit_mac_call(mac)),
         TyKind::Never | TyKind::CVarArgs => {}
-        TyKind::AnonStruct(_id, ref fields) | TyKind::AnonUnion(_id, ref fields) => {
-            walk_list!(visitor, visit_field_def, fields);
-        }
     }
     V::Result::output()
 }

compiler/rustc_ast_lowering/src/lib.rs

@@ -1264,46 +1264,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         let kind = match &t.kind {
             TyKind::Infer => hir::TyKind::Infer,
             TyKind::Err(guar) => hir::TyKind::Err(*guar),
-            // Lower the anonymous structs or unions in a nested lowering context.
-            //
-            // ```
-            // struct Foo {
-            //     _: union {
-            // //     ^__________________  <-- within the nested lowering context,
-            //         /* fields */ //   |     we lower all fields defined into an
-            //     } //                  |     owner node of struct or union item
-            // //  ^_____________________|
-            // }
-            // ```
-            TyKind::AnonStruct(node_id, fields) | TyKind::AnonUnion(node_id, fields) => {
-                // Here its `def_id` is created in `build_reduced_graph`.
-                let def_id = self.local_def_id(*node_id);
-                debug!(?def_id);
-                let owner_id = hir::OwnerId { def_id };
-                self.with_hir_id_owner(*node_id, |this| {
-                    let fields = this.arena.alloc_from_iter(
-                        fields.iter().enumerate().map(|f| this.lower_field_def(f)),
-                    );
-                    let span = t.span;
-                    let variant_data =
-                        hir::VariantData::Struct { fields, recovered: ast::Recovered::No };
-                    // FIXME: capture the generics from the outer adt.
-                    let generics = hir::Generics::empty();
-                    let kind = match t.kind {
-                        TyKind::AnonStruct(..) => hir::ItemKind::Struct(variant_data, generics),
-                        TyKind::AnonUnion(..) => hir::ItemKind::Union(variant_data, generics),
-                        _ => unreachable!(),
-                    };
-                    hir::OwnerNode::Item(this.arena.alloc(hir::Item {
-                        ident: Ident::new(kw::Empty, span),
-                        owner_id,
-                        kind,
-                        span: this.lower_span(span),
-                        vis_span: this.lower_span(span.shrink_to_lo()),
-                    }))
-                });
-                hir::TyKind::AnonAdt(hir::ItemId { owner_id })
-            }
             TyKind::Slice(ty) => hir::TyKind::Slice(self.lower_ty(ty, itctx)),
             TyKind::Ptr(mt) => hir::TyKind::Ptr(self.lower_mt(mt, itctx)),
             TyKind::Ref(region, mt) => {

compiler/rustc_ast_passes/messages.ftl

@@ -1,7 +1,3 @@
-ast_passes_anon_struct_or_union_not_allowed =
-    anonymous {$struct_or_union}s are not allowed outside of unnamed struct or union fields
-    .label = anonymous {$struct_or_union} declared here
-
 ast_passes_assoc_const_without_body =
     associated constant in `impl` without body
     .suggestion = provide a definition for the constant

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -244,9 +244,6 @@ impl<'a> AstValidator<'a> {
                     }
                 }
             }
-            TyKind::AnonStruct(_, ref fields) | TyKind::AnonUnion(_, ref fields) => {
-                walk_list!(self, visit_struct_field_def, fields)
-            }
             _ => visit::walk_ty(self, t),
         }
     }
@@ -293,15 +290,6 @@ impl<'a> AstValidator<'a> {
         }
     }
 
-    fn deny_anon_struct_or_union(&self, ty: &Ty) {
-        let struct_or_union = match &ty.kind {
-            TyKind::AnonStruct(..) => "struct",
-            TyKind::AnonUnion(..) => "union",
-            _ => return,
-        };
-        self.dcx().emit_err(errors::AnonStructOrUnionNotAllowed { struct_or_union, span: ty.span });
-    }
-
     fn check_trait_fn_not_const(&self, constness: Const, parent: &TraitOrTraitImpl) {
         let Const::Yes(span) = constness else {
             return;
@@ -865,14 +853,9 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
 
     fn visit_ty(&mut self, ty: &'a Ty) {
         self.visit_ty_common(ty);
-        self.deny_anon_struct_or_union(ty);
         self.walk_ty(ty)
     }
 
-    fn visit_field_def(&mut self, field: &'a FieldDef) {
-        visit::walk_field_def(self, field)
-    }
-
     fn visit_item(&mut self, item: &'a Item) {
         if item.attrs.iter().any(|attr| attr.is_proc_macro_attr()) {
             self.has_proc_macro_decls = true;

compiler/rustc_ast_passes/src/errors.rs

@@ -814,15 +814,6 @@ pub(crate) struct NegativeBoundWithParentheticalNotation {
     pub span: Span,
 }
 
-#[derive(Diagnostic)]
-#[diag(ast_passes_anon_struct_or_union_not_allowed)]
-pub(crate) struct AnonStructOrUnionNotAllowed {
-    #[primary_span]
-    #[label]
-    pub span: Span,
-    pub struct_or_union: &'static str,
-}
-
 #[derive(Diagnostic)]
 #[diag(ast_passes_match_arm_with_no_body)]
 pub(crate) struct MatchArmWithNoBody {

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -1174,14 +1174,6 @@ impl<'a> State<'a> {
                 }
                 self.pclose();
             }
-            ast::TyKind::AnonStruct(_, fields) => {
-                self.head("struct");
-                self.print_record_struct_body(fields, ty.span);
-            }
-            ast::TyKind::AnonUnion(_, fields) => {
-                self.head("union");
-                self.print_record_struct_body(fields, ty.span);
-            }
             ast::TyKind::Paren(typ) => {
                 self.popen();
                 self.print_type(typ);

compiler/rustc_builtin_macros/src/deriving/clone.rs

@@ -113,7 +113,7 @@ fn cs_clone_simple(
                 // Already produced an assertion for this type.
                 // Anonymous structs or unions must be eliminated as they cannot be
                 // type parameters.
-            } else if !field.ty.kind.is_anon_adt() {
+            } else {
                 // let _: AssertParamIsClone<FieldTy>;
                 super::assert_ty_bounds(cx, &mut stmts, field.ty.clone(), field.span, &[
                     sym::clone,