use the type name instead of Self in constructor paths again

compiler/rustc_builtin_macros/src/deriving/clone.rs

@@ -147,7 +147,7 @@ fn cs_clone_simple(
             &[sym::clone, sym::AssertParamIsCopy],
         );
     } else {
-        match substr {
+        match substr.fields {
             StaticStruct(vdata, ..) => {
                 process_variant(vdata);
             }
@@ -169,18 +169,17 @@ fn cs_clone(cx: &ExtCtxt<'_>, trait_span: Span, substr: Substructure<'_>) -> Blo
         cx.expr_call_global(field.span, fn_path.clone(), args)
     };
 
-    let self_ident = Ident::new(kw::SelfUpper, trait_span);
     let ctor_path;
     let all_fields;
     let vdata;
-    match substr {
+    match substr.fields {
         Struct(vdata_, af) => {
-            ctor_path = cx.path(trait_span, vec![self_ident]);
+            ctor_path = cx.path(trait_span, vec![substr.type_ident]);
             all_fields = af;
             vdata = vdata_;
         }
         EnumMatching(.., variant, af) => {
-            ctor_path = cx.path(trait_span, vec![self_ident, variant.ident]);
+            ctor_path = cx.path(trait_span, vec![substr.type_ident, variant.ident]);
             all_fields = af;
             vdata = &variant.data;
         }

compiler/rustc_builtin_macros/src/deriving/debug.rs

@@ -68,7 +68,7 @@ fn show_substructure(
         return BlockOrExpr::new_expr(cx.expr_ok(span, cx.expr_tuple(span, ThinVec::new())));
     }
 
-    let (ident, vdata, fields) = match substr {
+    let (ident, vdata, fields) = match substr.fields {
         Struct(vdata, fields) => (type_ident, vdata, fields),
         EnumMatching(v, fields) => (v.ident, &v.data, fields),
         AllFieldlessEnum(enum_def) => return show_fieldless_enum(cx, span, enum_def, type_ident),

compiler/rustc_builtin_macros/src/deriving/default.rs

@@ -37,9 +37,9 @@ pub(crate) fn expand_deriving_default(
             attributes: thin_vec![cx.attr_word(sym::inline, span)],
             fieldless_variants_strategy: FieldlessVariantsStrategy::Default,
             combine_substructure: combine_substructure(|cx, trait_span, substr| {
-                match substr {
+                match substr.fields {
                     StaticStruct(variant_data) => {
-                        default_struct_substructure(cx, trait_span, variant_data)
+                        default_struct_substructure(cx, trait_span, variant_data, substr.type_ident)
                     }
                     StaticEnum(enum_def) => {
                         default_enum_substructure(cx, trait_span, enum_def, item.span)
@@ -67,15 +67,16 @@ fn default_struct_substructure(
     cx: &ExtCtxt<'_>,
     trait_span: Span,
     variant_data: &VariantData,
+    type_ident: Ident,
 ) -> BlockOrExpr {
     let expr = match variant_data {
-        VariantData::Unit(_) => cx.expr_ident(trait_span, Ident::new(kw::SelfUpper, trait_span)),
+        VariantData::Unit(_) => cx.expr_ident(trait_span, type_ident),
         VariantData::Tuple(fields, _) => {
             let exprs = fields
                 .iter()
                 .map(|field| default_call(cx, field.span.with_ctxt(trait_span.ctxt())))
                 .collect();
-            cx.expr_call_ident(trait_span, Ident::new(kw::SelfUpper, trait_span), exprs)
+            cx.expr_call_ident(trait_span, type_ident, exprs)
         }
         VariantData::Struct { fields, .. } => {
             let default_fields = fields
@@ -95,7 +96,7 @@ fn default_struct_substructure(
                     cx.field_imm(span, field.ident.unwrap(), value)
                 })
                 .collect();
-            cx.expr_struct_ident(trait_span, Ident::new(kw::SelfUpper, trait_span), default_fields)
+            cx.expr_struct_ident(trait_span, type_ident, default_fields)
         }
     };
     BlockOrExpr::new_expr(expr)

compiler/rustc_builtin_macros/src/deriving/eq.rs

@@ -72,7 +72,7 @@ fn cs_total_eq_assert(cx: &ExtCtxt<'_>, trait_span: Span, substr: Substructure<'
         }
     };
 
-    match substr {
+    match substr.fields {
         StaticStruct(vdata, ..) => {
             process_variant(vdata);
         }

compiler/rustc_builtin_macros/src/deriving/from.rs

@@ -88,7 +88,7 @@ pub(crate) fn expand_deriving_from(
                 };
 
                 let self_kw = Ident::new(kw::SelfUpper, span);
-                let expr: Box<ast::Expr> = match substructure {
+                let expr: Box<ast::Expr> = match substructure.fields {
                     StaticStruct(variant) => match variant {
                         // Self { field: value }
                         VariantData::Struct { .. } => cx.expr_struct_ident(

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

@@ -177,7 +177,7 @@
 use std::ops::Not;
 use std::vec;
 
-pub(crate) use Substructure::*;
+pub(crate) use SubstructureFields::*;
 pub(crate) use rustc_ast as ast;
 use rustc_ast::token::{IdentKind, LitKind, Token, TokenKind};
 use rustc_ast::tokenstream::{DelimSpan, Spacing, TokenTree};
@@ -281,8 +281,16 @@ pub(crate) struct FieldInfo {
     pub maybe_scalar: bool,
 }
 
+pub(crate) struct Substructure<'a> {
+    pub fields: SubstructureFields<'a>,
+    // FIXME: this is currently required to avoid issues with attribute macros after derives,
+    // such as https://github.com/rust-lang/rust/issues/163800.
+    // Ideally we would just use `Self` instead.
+    pub type_ident: Ident,
+}
+
 /// A summary of the possible sets of fields.
-pub(crate) enum Substructure<'a> {
+pub(crate) enum SubstructureFields<'a> {
     /// A non-static method where `Self` is a struct.
     Struct(&'a ast::VariantData, Vec<FieldInfo>),
 
@@ -474,9 +482,15 @@ impl<'a> TraitDef<'a> {
                 let fields = struct_def.fields().iter();
                 let methods = self.methods.iter().filter_map(|method_def| {
                     let body = if from_scratch || method_def.is_static() {
-                        method_def.call_substructure_method(cx, span, StaticStruct(struct_def))
+                        method_def.call_substructure_method(
+                            cx,
+                            span,
+                            StaticStruct(struct_def),
+                            *ident,
+                        )
                     } else {
-                        method_def.expand_struct_method_body(cx, span, struct_def, is_packed)
+                        method_def
+                            .expand_struct_method_body(cx, span, struct_def, is_packed, *ident)
                     };
 
                     method_def.create_method(cx, span, body)
@@ -494,9 +508,9 @@ impl<'a> TraitDef<'a> {
                 let fields = enum_def.variants.iter().flat_map(|variant| variant.data.fields());
                 let methods = self.methods.iter().filter_map(|method_def| {
                     let body = if from_scratch || method_def.is_static() {
-                        method_def.call_substructure_method(cx, span, StaticEnum(enum_def))
+                        method_def.call_substructure_method(cx, span, StaticEnum(enum_def), *ident)
                     } else {
-                        method_def.expand_enum_method_body(cx, span, enum_def)
+                        method_def.expand_enum_method_body(cx, span, enum_def, *ident)
                     };
 
                     method_def.create_method(cx, span, body)
@@ -778,9 +792,10 @@ impl<'a> MethodDef<'a> {
         &self,
         cx: &ExtCtxt<'_>,
         span: Span,
-        substructure: Substructure<'_>,
+        fields: SubstructureFields<'_>,
+        type_ident: Ident,
     ) -> BlockOrExpr {
-        (self.combine_substructure)(cx, span, substructure)
+        (self.combine_substructure)(cx, span, Substructure { fields, type_ident })
     }
 
     fn is_static(&self) -> bool {
@@ -906,12 +921,13 @@ impl<'a> MethodDef<'a> {
         span: Span,
         struct_def: &'b VariantData,
         is_packed: bool,
+        type_ident: Ident,
     ) -> BlockOrExpr {
         let selflike_args = self.get_selflike_args(cx, span);
 
         let selflike_fields =
             create_struct_field_access_fields(span, cx, &selflike_args, struct_def, is_packed);
-        self.call_substructure_method(cx, span, Struct(struct_def, selflike_fields))
+        self.call_substructure_method(cx, span, Struct(struct_def, selflike_fields), type_ident)
     }
 
     /// ```
@@ -954,6 +970,7 @@ impl<'a> MethodDef<'a> {
         cx: &ExtCtxt<'_>,
         span: Span,
         enum_def: &'b EnumDef,
+        type_ident: Ident,
     ) -> BlockOrExpr {
         let variants = &enum_def.variants;
 
@@ -989,17 +1006,32 @@ impl<'a> MethodDef<'a> {
                         // If the type is fieldless and the trait uses the discriminant and
                         // there are multiple variants, we need just an operation on
                         // the discriminant(s).
-                        return self.call_substructure_method(cx, span, EnumDiscr(None));
+                        return self.call_substructure_method(
+                            cx,
+                            span,
+                            EnumDiscr(None),
+                            type_ident,
+                        );
                     }
                     FieldlessVariantsStrategy::SpecializeIfAllVariantsFieldless => {
-                        return self.call_substructure_method(cx, span, AllFieldlessEnum(enum_def));
+                        return self.call_substructure_method(
+                            cx,
+                            span,
+                            AllFieldlessEnum(enum_def),
+                            type_ident,
+                        );
                     }
                     FieldlessVariantsStrategy::Default => (),
                 }
             } else if let [variant] = variants.as_slice() {
                 // If there is a single variant, we don't need an operation on
                 // the discriminant(s). Just use the most degenerate result.
-                return self.call_substructure_method(cx, span, EnumMatching(variant, Vec::new()));
+                return self.call_substructure_method(
+                    cx,
+                    span,
+                    EnumMatching(variant, Vec::new()),
+                    type_ident,
+                );
             }
         }
 
@@ -1039,8 +1071,9 @@ impl<'a> MethodDef<'a> {
                 // Self arg, assuming all are instances of VariantK.
                 // Build up code associated with such a case.
                 let substructure = EnumMatching(variant, fields);
-                let arm_expr =
-                    self.call_substructure_method(cx, span, substructure).into_expr(cx, span);
+                let arm_expr = self
+                    .call_substructure_method(cx, span, substructure, type_ident)
+                    .into_expr(cx, span);
 
                 cx.arm(span, single_pat, arm_expr)
             })
@@ -1052,8 +1085,13 @@ impl<'a> MethodDef<'a> {
             Some(v) if unify_fieldless_variants => {
                 // We need a default case that handles all the fieldless variants.
                 Some(
-                    self.call_substructure_method(cx, span, EnumMatching(v, Vec::new()))
-                        .into_expr(cx, span),
+                    self.call_substructure_method(
+                        cx,
+                        span,
+                        EnumMatching(v, Vec::new()),
+                        type_ident,
+                    )
+                    .into_expr(cx, span),
                 )
             }
             _ if variants.len() > 1 && selflike_args.len() > 1 => {
@@ -1090,7 +1128,12 @@ impl<'a> MethodDef<'a> {
         // is enough.
         if unify_fieldless_variants && variants.len() > 1 {
             // Combine a discriminant check with the match.
-            self.call_substructure_method(cx, span, EnumDiscr(Some(get_match_expr(selflike_args))))
+            self.call_substructure_method(
+                cx,
+                span,
+                EnumDiscr(Some(get_match_expr(selflike_args))),
+                type_ident,
+            )
         } else {
             BlockOrExpr(ThinVec::new(), Some(get_match_expr(selflike_args)))
         }

compiler/rustc_builtin_macros/src/deriving/hash.rs

@@ -65,7 +65,7 @@ fn hash_substructure(cx: &ExtCtxt<'_>, span: Span, substr: Substructure<'_>) ->
         cx.stmt_expr(expr)
     };
 
-    let (stmts, match_expr) = match substr {
+    let (stmts, match_expr) = match substr.fields {
         Struct(_, fields) | EnumMatching(.., fields) => {
             let stmts =
                 fields.into_iter().map(|field| call_hash(field.span, field.self_expr)).collect();

compiler/rustc_builtin_macros/src/deriving/partial_eq.rs

@@ -119,7 +119,7 @@ fn get_substructure_equality_expr(
     span: Span,
     substructure: Substructure<'_>,
 ) -> BlockOrExpr {
-    BlockOrExpr::new_expr(match substructure {
+    BlockOrExpr::new_expr(match substructure.fields {
         EnumMatching(.., fields) | Struct(.., fields) => {
             let combine = move |acc, field: &FieldInfo| {
                 let rhs = field

compiler/rustc_builtin_macros/src/deriving/partial_ord.rs

@@ -202,7 +202,7 @@ pub(crate) fn cmp_body(
         }
     };
 
-    match substructure {
+    match substructure.fields {
         EnumMatching(.., all_fields) | Struct(_, all_fields) => {
             let op = |old, field: FieldInfo| {
                 // The basic case: a field expression for one or more selflike args. E.g.

tests/ui/derives/attr-macro-changes-type-kind.rs

@@ -0,0 +1,15 @@
+//! Regression test for https://github.com/rust-lang/rust/issues/163800,
+//! where the generated code always referred to `Self`, which was invalid
+//! when an attribute macro rewrites the type to an enum.
+
+//@ check-pass
+//@ proc-macro: struct-to-enum.rs
+
+extern crate struct_to_enum;
+use struct_to_enum::*;
+
+#[derive(Clone, Copy, Default, Hash, PartialEq, Eq, PartialOrd, Ord, Debug)]
+#[struct_to_enum::phantom]
+struct Spooky<T>;
+
+fn main() {}

tests/ui/derives/auxiliary/struct-to-enum.rs

@@ -0,0 +1,18 @@
+extern crate proc_macro;
+use proc_macro::TokenStream;
+
+#[proc_macro_attribute]
+pub fn phantom(_: TokenStream, _: TokenStream) -> TokenStream {
+    "
+mod __value_Spooky {
+    pub use super::Spooky::Spooky;
+}
+pub enum Spooky<T> {
+    __Phantom(std::marker::PhantomData<T>),
+    Spooky,
+}
+pub use self::__value_Spooky::*;
+    "
+    .parse()
+    .unwrap()
+}