Rollup merge of #140878 - nnethercote:two-expand-cleanups, r=compiler-errors

Two expand-related cleanups

Minor improvements I found while looking at this code. Best reviewed one commit at a time.

r? `@BoxyUwU`

5 files changed, 45 insertions, 71 deletions

diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs
index 114b9835b98..4ace80a7344 100644
--- a/compiler/rustc_ast/src/ast.rs
+++ b/compiler/rustc_ast/src/ast.rs
@@ -308,7 +308,6 @@ impl ParenthesizedArgs {
     }
 }
 
-use crate::AstDeref;
 pub use crate::node_id::{CRATE_NODE_ID, DUMMY_NODE_ID, NodeId};
 
 /// Modifiers on a trait bound like `~const`, `?` and `!`.
@@ -2349,7 +2348,7 @@ impl Ty {
     pub fn is_maybe_parenthesised_infer(&self) -> bool {
         match &self.kind {
             TyKind::Infer => true,
-            TyKind::Paren(inner) => inner.ast_deref().is_maybe_parenthesised_infer(),
+            TyKind::Paren(inner) => inner.is_maybe_parenthesised_infer(),
             _ => false,
         }
     }
diff --git a/compiler/rustc_ast/src/ast_traits.rs b/compiler/rustc_ast/src/ast_traits.rs
index 7f98e7ba8a6..21de7ff7719 100644
--- a/compiler/rustc_ast/src/ast_traits.rs
+++ b/compiler/rustc_ast/src/ast_traits.rs
@@ -13,34 +13,6 @@ use crate::{
     Ty, Variant, Visibility, WherePredicate,
 };
 
-/// A utility trait to reduce boilerplate.
-/// Standard `Deref(Mut)` cannot be reused due to coherence.
-pub trait AstDeref {
-    type Target;
-    fn ast_deref(&self) -> &Self::Target;
-    fn ast_deref_mut(&mut self) -> &mut Self::Target;
-}
-
-macro_rules! impl_not_ast_deref {
-    ($($T:ty),+ $(,)?) => {
-        $(
-            impl !AstDeref for $T {}
-        )+
-    };
-}
-
-impl_not_ast_deref!(AssocItem, Expr, ForeignItem, Item, Stmt);
-
-impl<T> AstDeref for P<T> {
-    type Target = T;
-    fn ast_deref(&self) -> &Self::Target {
-        self
-    }
-    fn ast_deref_mut(&mut self) -> &mut Self::Target {
-        self
-    }
-}
-
 /// A trait for AST nodes having an ID.
 pub trait HasNodeId {
     fn node_id(&self) -> NodeId;
@@ -81,12 +53,12 @@ impl_has_node_id!(
     WherePredicate,
 );
 
-impl<T: AstDeref<Target: HasNodeId>> HasNodeId for T {
+impl<T: HasNodeId> HasNodeId for P<T> {
     fn node_id(&self) -> NodeId {
-        self.ast_deref().node_id()
+        (**self).node_id()
     }
     fn node_id_mut(&mut self) -> &mut NodeId {
-        self.ast_deref_mut().node_id_mut()
+        (**self).node_id_mut()
     }
 }
 
@@ -138,21 +110,21 @@ impl_has_tokens_none!(
     WherePredicate
 );
 
-impl<T: AstDeref<Target: HasTokens>> HasTokens for T {
+impl<T: HasTokens> HasTokens for Option<T> {
     fn tokens(&self) -> Option<&LazyAttrTokenStream> {
-        self.ast_deref().tokens()
+        self.as_ref().and_then(|inner| inner.tokens())
     }
     fn tokens_mut(&mut self) -> Option<&mut Option<LazyAttrTokenStream>> {
-        self.ast_deref_mut().tokens_mut()
+        self.as_mut().and_then(|inner| inner.tokens_mut())
     }
 }
 
-impl<T: HasTokens> HasTokens for Option<T> {
+impl<T: HasTokens> HasTokens for P<T> {
     fn tokens(&self) -> Option<&LazyAttrTokenStream> {
-        self.as_ref().and_then(|inner| inner.tokens())
+        (**self).tokens()
     }
     fn tokens_mut(&mut self) -> Option<&mut Option<LazyAttrTokenStream>> {
-        self.as_mut().and_then(|inner| inner.tokens_mut())
+        (**self).tokens_mut()
     }
 }
 
@@ -273,13 +245,13 @@ impl_has_attrs!(
 );
 impl_has_attrs_none!(Attribute, AttrItem, Block, Pat, Path, Ty, Visibility);
 
-impl<T: AstDeref<Target: HasAttrs>> HasAttrs for T {
-    const SUPPORTS_CUSTOM_INNER_ATTRS: bool = T::Target::SUPPORTS_CUSTOM_INNER_ATTRS;
+impl<T: HasAttrs> HasAttrs for P<T> {
+    const SUPPORTS_CUSTOM_INNER_ATTRS: bool = T::SUPPORTS_CUSTOM_INNER_ATTRS;
     fn attrs(&self) -> &[Attribute] {
-        self.ast_deref().attrs()
+        (**self).attrs()
     }
     fn visit_attrs(&mut self, f: impl FnOnce(&mut AttrVec)) {
-        self.ast_deref_mut().visit_attrs(f)
+        (**self).visit_attrs(f);
     }
 }
 
@@ -343,13 +315,22 @@ impl<Wrapped, Tag> AstNodeWrapper<Wrapped, Tag> {
     }
 }
 
-impl<Wrapped, Tag> AstDeref for AstNodeWrapper<Wrapped, Tag> {
-    type Target = Wrapped;
-    fn ast_deref(&self) -> &Self::Target {
-        &self.wrapped
+impl<Wrapped: HasNodeId, Tag> HasNodeId for AstNodeWrapper<Wrapped, Tag> {
+    fn node_id(&self) -> NodeId {
+        self.wrapped.node_id()
+    }
+    fn node_id_mut(&mut self) -> &mut NodeId {
+        self.wrapped.node_id_mut()
+    }
+}
+
+impl<Wrapped: HasAttrs, Tag> HasAttrs for AstNodeWrapper<Wrapped, Tag> {
+    const SUPPORTS_CUSTOM_INNER_ATTRS: bool = Wrapped::SUPPORTS_CUSTOM_INNER_ATTRS;
+    fn attrs(&self) -> &[Attribute] {
+        self.wrapped.attrs()
     }
-    fn ast_deref_mut(&mut self) -> &mut Self::Target {
-        &mut self.wrapped
+    fn visit_attrs(&mut self, f: impl FnOnce(&mut AttrVec)) {
+        self.wrapped.visit_attrs(f);
     }
 }
 
diff --git a/compiler/rustc_ast/src/lib.rs b/compiler/rustc_ast/src/lib.rs
index e572ec99dab..c08622cac86 100644
--- a/compiler/rustc_ast/src/lib.rs
+++ b/compiler/rustc_ast/src/lib.rs
@@ -46,7 +46,7 @@ pub mod tokenstream;
 pub mod visit;
 
 pub use self::ast::*;
-pub use self::ast_traits::{AstDeref, AstNodeWrapper, HasAttrs, HasNodeId, HasTokens};
+pub use self::ast_traits::{AstNodeWrapper, HasAttrs, HasNodeId, HasTokens};
 
 /// Requirements for a `StableHashingContext` to be used in this crate.
 /// This is a hack to allow using the `HashStable_Generic` derive macro
diff --git a/compiler/rustc_builtin_macros/src/env.rs b/compiler/rustc_builtin_macros/src/env.rs
index 0913dc91a53..f3ac932e1b7 100644
--- a/compiler/rustc_builtin_macros/src/env.rs
+++ b/compiler/rustc_builtin_macros/src/env.rs
@@ -8,7 +8,7 @@ use std::env::VarError;
 
 use rustc_ast::token::{self, LitKind};
 use rustc_ast::tokenstream::TokenStream;
-use rustc_ast::{AstDeref, ExprKind, GenericArg, Mutability};
+use rustc_ast::{ExprKind, GenericArg, Mutability};
 use rustc_expand::base::{DummyResult, ExpandResult, ExtCtxt, MacEager, MacroExpanderResult};
 use rustc_span::{Ident, Span, Symbol, kw, sym};
 use thin_vec::thin_vec;
@@ -148,13 +148,13 @@ pub(crate) fn expand_env<'cx>(
                         cx.dcx().emit_err(errors::EnvNotDefined::CargoEnvVar {
                             span,
                             var: *symbol,
-                            var_expr: var_expr.ast_deref(),
+                            var_expr: &var_expr,
                         })
                     } else {
                         cx.dcx().emit_err(errors::EnvNotDefined::CustomEnvVar {
                             span,
                             var: *symbol,
-                            var_expr: var_expr.ast_deref(),
+                            var_expr: &var_expr,
                         })
                     }
                 }
diff --git a/compiler/rustc_expand/src/expand.rs b/compiler/rustc_expand/src/expand.rs
index d4853d1357f..81d4d59ee04 100644
--- a/compiler/rustc_expand/src/expand.rs
+++ b/compiler/rustc_expand/src/expand.rs
@@ -1,4 +1,3 @@
-use std::ops::Deref;
 use std::path::PathBuf;
 use std::rc::Rc;
 use std::sync::Arc;
@@ -1117,7 +1116,6 @@ enum AddSemicolon {
 /// of functionality used by `InvocationCollector`.
 trait InvocationCollectorNode: HasAttrs + HasNodeId + Sized {
     type OutputTy = SmallVec<[Self; 1]>;
-    type AttrsTy: Deref<Target = [ast::Attribute]> = ast::AttrVec;
     type ItemKind = ItemKind;
     const KIND: AstFragmentKind;
     fn to_annotatable(self) -> Annotatable;
@@ -1134,7 +1132,7 @@ trait InvocationCollectorNode: HasAttrs + HasNodeId + Sized {
     fn is_mac_call(&self) -> bool {
         false
     }
-    fn take_mac_call(self) -> (P<ast::MacCall>, Self::AttrsTy, AddSemicolon) {
+    fn take_mac_call(self) -> (P<ast::MacCall>, ast::AttrVec, AddSemicolon) {
         unreachable!()
     }
     fn delegation(&self) -> Option<(&ast::DelegationMac, &ast::Item<Self::ItemKind>)> {
@@ -1189,7 +1187,7 @@ impl InvocationCollectorNode for P<ast::Item> {
     fn is_mac_call(&self) -> bool {
         matches!(self.kind, ItemKind::MacCall(..))
     }
-    fn take_mac_call(self) -> (P<ast::MacCall>, Self::AttrsTy, AddSemicolon) {
+    fn take_mac_call(self) -> (P<ast::MacCall>, ast::AttrVec, AddSemicolon) {
         let node = self.into_inner();
         match node.kind {
             ItemKind::MacCall(mac) => (mac, node.attrs, AddSemicolon::No),
@@ -1345,7 +1343,7 @@ impl InvocationCollectorNode for AstNodeWrapper<P<ast::AssocItem>, TraitItemTag>
     fn is_mac_call(&self) -> bool {
         matches!(self.wrapped.kind, AssocItemKind::MacCall(..))
     }
-    fn take_mac_call(self) -> (P<ast::MacCall>, Self::AttrsTy, AddSemicolon) {
+    fn take_mac_call(self) -> (P<ast::MacCall>, ast::AttrVec, AddSemicolon) {
         let item = self.wrapped.into_inner();
         match item.kind {
             AssocItemKind::MacCall(mac) => (mac, item.attrs, AddSemicolon::No),
@@ -1386,7 +1384,7 @@ impl InvocationCollectorNode for AstNodeWrapper<P<ast::AssocItem>, ImplItemTag>
     fn is_mac_call(&self) -> bool {
         matches!(self.wrapped.kind, AssocItemKind::MacCall(..))
     }
-    fn take_mac_call(self) -> (P<ast::MacCall>, Self::AttrsTy, AddSemicolon) {
+    fn take_mac_call(self) -> (P<ast::MacCall>, ast::AttrVec, AddSemicolon) {
         let item = self.wrapped.into_inner();
         match item.kind {
             AssocItemKind::MacCall(mac) => (mac, item.attrs, AddSemicolon::No),
@@ -1427,7 +1425,7 @@ impl InvocationCollectorNode for AstNodeWrapper<P<ast::AssocItem>, TraitImplItem
     fn is_mac_call(&self) -> bool {
         matches!(self.wrapped.kind, AssocItemKind::MacCall(..))
     }
-    fn take_mac_call(self) -> (P<ast::MacCall>, Self::AttrsTy, AddSemicolon) {
+    fn take_mac_call(self) -> (P<ast::MacCall>, ast::AttrVec, AddSemicolon) {
         let item = self.wrapped.into_inner();
         match item.kind {
             AssocItemKind::MacCall(mac) => (mac, item.attrs, AddSemicolon::No),
@@ -1465,7 +1463,7 @@ impl InvocationCollectorNode for P<ast::ForeignItem> {
     fn is_mac_call(&self) -> bool {
         matches!(self.kind, ForeignItemKind::MacCall(..))
     }
-    fn take_mac_call(self) -> (P<ast::MacCall>, Self::AttrsTy, AddSemicolon) {
+    fn take_mac_call(self) -> (P<ast::MacCall>, ast::AttrVec, AddSemicolon) {
         let node = self.into_inner();
         match node.kind {
             ForeignItemKind::MacCall(mac) => (mac, node.attrs, AddSemicolon::No),
@@ -1579,7 +1577,6 @@ impl InvocationCollectorNode for ast::Arm {
 }
 
 impl InvocationCollectorNode for ast::Stmt {
-    type AttrsTy = ast::AttrVec;
     const KIND: AstFragmentKind = AstFragmentKind::Stmts;
     fn to_annotatable(self) -> Annotatable {
         Annotatable::Stmt(P(self))
@@ -1599,7 +1596,7 @@ impl InvocationCollectorNode for ast::Stmt {
             StmtKind::Let(..) | StmtKind::Empty => false,
         }
     }
-    fn take_mac_call(self) -> (P<ast::MacCall>, Self::AttrsTy, AddSemicolon) {
+    fn take_mac_call(self) -> (P<ast::MacCall>, ast::AttrVec, AddSemicolon) {
         // We pull macro invocations (both attributes and fn-like macro calls) out of their
         // `StmtKind`s and treat them as statement macro invocations, not as items or expressions.
         let (add_semicolon, mac, attrs) = match self.kind {
@@ -1693,7 +1690,7 @@ impl InvocationCollectorNode for P<ast::Ty> {
     fn is_mac_call(&self) -> bool {
         matches!(self.kind, ast::TyKind::MacCall(..))
     }
-    fn take_mac_call(self) -> (P<ast::MacCall>, Self::AttrsTy, AddSemicolon) {
+    fn take_mac_call(self) -> (P<ast::MacCall>, ast::AttrVec, AddSemicolon) {
         let node = self.into_inner();
         match node.kind {
             TyKind::MacCall(mac) => (mac, AttrVec::new(), AddSemicolon::No),
@@ -1717,7 +1714,7 @@ impl InvocationCollectorNode for P<ast::Pat> {
     fn is_mac_call(&self) -> bool {
         matches!(self.kind, PatKind::MacCall(..))
     }
-    fn take_mac_call(self) -> (P<ast::MacCall>, Self::AttrsTy, AddSemicolon) {
+    fn take_mac_call(self) -> (P<ast::MacCall>, ast::AttrVec, AddSemicolon) {
         let node = self.into_inner();
         match node.kind {
             PatKind::MacCall(mac) => (mac, AttrVec::new(), AddSemicolon::No),
@@ -1728,7 +1725,6 @@ impl InvocationCollectorNode for P<ast::Pat> {
 
 impl InvocationCollectorNode for P<ast::Expr> {
     type OutputTy = P<ast::Expr>;
-    type AttrsTy = ast::AttrVec;
     const KIND: AstFragmentKind = AstFragmentKind::Expr;
     fn to_annotatable(self) -> Annotatable {
         Annotatable::Expr(self)
@@ -1745,7 +1741,7 @@ impl InvocationCollectorNode for P<ast::Expr> {
     fn is_mac_call(&self) -> bool {
         matches!(self.kind, ExprKind::MacCall(..))
     }
-    fn take_mac_call(self) -> (P<ast::MacCall>, Self::AttrsTy, AddSemicolon) {
+    fn take_mac_call(self) -> (P<ast::MacCall>, ast::AttrVec, AddSemicolon) {
         let node = self.into_inner();
         match node.kind {
             ExprKind::MacCall(mac) => (mac, node.attrs, AddSemicolon::No),
@@ -1757,7 +1753,6 @@ impl InvocationCollectorNode for P<ast::Expr> {
 struct OptExprTag;
 impl InvocationCollectorNode for AstNodeWrapper<P<ast::Expr>, OptExprTag> {
     type OutputTy = Option<P<ast::Expr>>;
-    type AttrsTy = ast::AttrVec;
     const KIND: AstFragmentKind = AstFragmentKind::OptExpr;
     fn to_annotatable(self) -> Annotatable {
         Annotatable::Expr(self.wrapped)
@@ -1772,7 +1767,7 @@ impl InvocationCollectorNode for AstNodeWrapper<P<ast::Expr>, OptExprTag> {
     fn is_mac_call(&self) -> bool {
         matches!(self.wrapped.kind, ast::ExprKind::MacCall(..))
     }
-    fn take_mac_call(self) -> (P<ast::MacCall>, Self::AttrsTy, AddSemicolon) {
+    fn take_mac_call(self) -> (P<ast::MacCall>, ast::AttrVec, AddSemicolon) {
         let node = self.wrapped.into_inner();
         match node.kind {
             ExprKind::MacCall(mac) => (mac, node.attrs, AddSemicolon::No),
@@ -1794,7 +1789,6 @@ impl DummyAstNode for MethodReceiverTag {
 }
 impl InvocationCollectorNode for AstNodeWrapper<P<ast::Expr>, MethodReceiverTag> {
     type OutputTy = Self;
-    type AttrsTy = ast::AttrVec;
     const KIND: AstFragmentKind = AstFragmentKind::MethodReceiverExpr;
     fn descr() -> &'static str {
         "an expression"
@@ -1811,7 +1805,7 @@ impl InvocationCollectorNode for AstNodeWrapper<P<ast::Expr>, MethodReceiverTag>
     fn is_mac_call(&self) -> bool {
         matches!(self.wrapped.kind, ast::ExprKind::MacCall(..))
     }
-    fn take_mac_call(self) -> (P<ast::MacCall>, Self::AttrsTy, AddSemicolon) {
+    fn take_mac_call(self) -> (P<ast::MacCall>, ast::AttrVec, AddSemicolon) {
         let node = self.wrapped.into_inner();
         match node.kind {
             ExprKind::MacCall(mac) => (mac, node.attrs, AddSemicolon::No),