Auto merge of rust-lang#132046 - lcnr:trivial-type-visitable, r=<try>

'improve' type traversal

questionable :3

r? `@ghost`

compiler/rustc_infer/src/infer/canonical/query_response.rs

@@ -15,8 +15,10 @@ use rustc_index::{Idx, IndexVec};
 use rustc_middle::arena::ArenaAllocatable;
 use rustc_middle::mir::ConstraintCategory;
 use rustc_middle::ty::fold::TypeFoldable;
+use rustc_middle::ty::traverse::AlwaysTraversable;
 use rustc_middle::ty::{self, BoundVar, GenericArg, GenericArgKind, Ty, TyCtxt};
 use rustc_middle::{bug, span_bug};
+use rustc_type_ir::traverse::OptTryFoldWith;
 use tracing::{debug, instrument};
 
 use crate::infer::canonical::instantiate::{CanonicalExt, instantiate_value};
@@ -60,7 +62,7 @@ impl<'tcx> InferCtxt<'tcx> {
  fulfill_cx: &mut dyn TraitEngine<'tcx, ScrubbedTraitError<'tcx>>,
  ) -> Result<CanonicalQueryResponse<'tcx, T>, NoSolution>
  where
- T: Debug + TypeFoldable<TyCtxt<'tcx>>,
+ T: OptTryFoldWith<TyCtxt<'tcx>>,
  Canonical<'tcx, QueryResponse<'tcx, T>>: ArenaAllocatable<'tcx>,
  {
  let query_response = self.make_query_response(inference_vars, answer, fulfill_cx)?;
@@ -107,7 +109,7 @@ impl<'tcx> InferCtxt<'tcx> {
  fulfill_cx: &mut dyn TraitEngine<'tcx, ScrubbedTraitError<'tcx>>,
  ) -> Result<QueryResponse<'tcx, T>, NoSolution>
  where
- T: Debug + TypeFoldable<TyCtxt<'tcx>>,
+ T: OptTryFoldWith<TyCtxt<'tcx>>,
  {
  let tcx = self.tcx;
 
@@ -243,7 +245,7 @@ impl<'tcx> InferCtxt<'tcx> {
  output_query_region_constraints: &mut QueryRegionConstraints<'tcx>,
  ) -> InferResult<'tcx, R>
  where
- R: Debug + TypeFoldable<TyCtxt<'tcx>>,
+ R: OptTryFoldWith<TyCtxt<'tcx>>,
  {
  let InferOk { value: result_args, mut obligations } = self
  .query_response_instantiation_guess(
@@ -326,8 +328,11 @@ impl<'tcx> InferCtxt<'tcx> {
  .map(|p_c| instantiate_value(self.tcx, &result_args, p_c.clone())),
  );
 
- let user_result: R =
- query_response.instantiate_projected(self.tcx, &result_args, |q_r| q_r.value.clone());
+ let user_result: R = query_response
+ .instantiate_projected(self.tcx, &result_args, |q_r| {
+ AlwaysTraversable(q_r.value.clone())
+ })
+ .0;
 
  Ok(InferOk { value: user_result, obligations })
  }
@@ -396,7 +401,7 @@ impl<'tcx> InferCtxt<'tcx> {
  query_response: &Canonical<'tcx, QueryResponse<'tcx, R>>,
  ) -> InferResult<'tcx, CanonicalVarValues<'tcx>>
  where
- R: Debug + TypeFoldable<TyCtxt<'tcx>>,
+ R: OptTryFoldWith<TyCtxt<'tcx>>,
  {
  // For each new universe created in the query result that did
  // not appear in the original query, create a local

compiler/rustc_infer/src/traits/structural_impls.rs

@@ -4,6 +4,7 @@ use rustc_ast_ir::try_visit;
 use rustc_middle::ty::fold::{FallibleTypeFolder, TypeFoldable};
 use rustc_middle::ty::visit::{TypeVisitable, TypeVisitor};
 use rustc_middle::ty::{self, TyCtxt};
+use rustc_type_ir::traverse::{ImportantTypeTraversal, TypeTraversable};
 
 use crate::traits;
 use crate::traits::project::Normalized;
@@ -55,6 +56,11 @@ impl<'tcx, O: TypeFoldable<TyCtxt<'tcx>>> TypeFoldable<TyCtxt<'tcx>>
  }
 }
 
+impl<'tcx, O: TypeVisitable<TyCtxt<'tcx>>> TypeTraversable<TyCtxt<'tcx>>
+ for traits::Obligation<'tcx, O>
+{
+ type Kind = ImportantTypeTraversal;
+}
 impl<'tcx, O: TypeVisitable<TyCtxt<'tcx>>> TypeVisitable<TyCtxt<'tcx>>
  for traits::Obligation<'tcx, O>
 {

compiler/rustc_macros/src/lib.rs

@@ -17,6 +17,7 @@ mod diagnostics;
 mod extension;
 mod hash_stable;
 mod lift;
+mod noop_type_traversable;
 mod query;
 mod serialize;
 mod symbols;
@@ -81,27 +82,9 @@ decl_derive!([TyDecodable] => serialize::type_decodable_derive);
 decl_derive!([TyEncodable] => serialize::type_encodable_derive);
 decl_derive!([MetadataDecodable] => serialize::meta_decodable_derive);
 decl_derive!([MetadataEncodable] => serialize::meta_encodable_derive);
-decl_derive!(
- [TypeFoldable, attributes(type_foldable)] =>
- /// Derives `TypeFoldable` for the annotated `struct` or `enum` (`union` is not supported).
- ///
- /// The fold will produce a value of the same struct or enum variant as the input, with
- /// each field respectively folded using the `TypeFoldable` implementation for its type.
- /// However, if a field of a struct or an enum variant is annotated with
- /// `#[type_foldable(identity)]` then that field will retain its incumbent value (and its
- /// type is not required to implement `TypeFoldable`).
- type_foldable::type_foldable_derive
-);
-decl_derive!(
- [TypeVisitable, attributes(type_visitable)] =>
- /// Derives `TypeVisitable` for the annotated `struct` or `enum` (`union` is not supported).
- ///
- /// Each field of the struct or enum variant will be visited in definition order, using the
- /// `TypeVisitable` implementation for its type. However, if a field of a struct or an enum
- /// variant is annotated with `#[type_visitable(ignore)]` then that field will not be
- /// visited (and its type is not required to implement `TypeVisitable`).
- type_visitable::type_visitable_derive
-);
+decl_derive!([NoopTypeTraversable] => noop_type_traversable::noop_type_traversable_derive);
+decl_derive!([TypeVisitable] => type_visitable::type_visitable_derive);
+decl_derive!([TypeFoldable] => type_foldable::type_foldable_derive);
 decl_derive!([Lift, attributes(lift)] => lift::lift_derive);
 decl_derive!(
  [Diagnostic, attributes(

compiler/rustc_macros/src/noop_type_traversable.rs

@@ -0,0 +1,39 @@
+use quote::quote;
+use syn::parse_quote;
+
+pub(super) fn noop_type_traversable_derive(
+ mut s: synstructure::Structure<'_>,
+) -> proc_macro2::TokenStream {
+ if let syn::Data::Union(_) = s.ast().data {
+ panic!("cannot derive on union")
+ }
+
+ s.underscore_const(true);
+
+ if !s.ast().generics.lifetimes().any(|lt| lt.lifetime.ident == "tcx") {
+ s.add_impl_generic(parse_quote! { 'tcx });
+ }
+
+ s.add_bounds(synstructure::AddBounds::None);
+ let mut where_clauses = None;
+ s.add_trait_bounds(
+ &parse_quote!(
+ ::rustc_middle::ty::traverse::TypeTraversable<
+ ::rustc_middle::ty::TyCtxt<'tcx>,
+ Kind = ::rustc_middle::ty::traverse::NoopTypeTraversal,
+ >
+ ),
+ &mut where_clauses,
+ synstructure::AddBounds::Fields,
+ );
+ for pred in where_clauses.into_iter().flat_map(|c| c.predicates) {
+ s.add_where_predicate(pred);
+ }
+
+ s.bound_impl(
+ quote!(::rustc_middle::ty::traverse::TypeTraversable<::rustc_middle::ty::TyCtxt<'tcx>>),
+ quote! {
+ type Kind = ::rustc_middle::ty::traverse::NoopTypeTraversal;
+ },
+ )
+}

compiler/rustc_macros/src/type_foldable.rs

@@ -1,4 +1,4 @@
-use quote::{ToTokens, quote};
+use quote::quote;
 use syn::parse_quote;
 
 pub(super) fn type_foldable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
@@ -12,34 +12,25 @@ pub(super) fn type_foldable_derive(mut s: synstructure::Structure<'_>) -> proc_m
  s.add_impl_generic(parse_quote! { 'tcx });
  }
 
- s.add_bounds(synstructure::AddBounds::Generics);
+ s.add_bounds(synstructure::AddBounds::None);
+ let mut where_clauses = None;
+ s.add_trait_bounds(
+ &parse_quote!(::rustc_type_ir::traverse::OptTryFoldWith<::rustc_middle::ty::TyCtxt<'tcx>>),
+ &mut where_clauses,
+ synstructure::AddBounds::Fields,
+ );
+ s.add_where_predicate(parse_quote! { Self: std::fmt::Debug + Clone });
+ for pred in where_clauses.into_iter().flat_map(|c| c.predicates) {
+ s.add_where_predicate(pred);
+ }
+
  s.bind_with(|_| synstructure::BindStyle::Move);
  let body_fold = s.each_variant(|vi| {
  let bindings = vi.bindings();
  vi.construct(|_, index| {
  let bind = &bindings[index];
-
- let mut fixed = false;
-
- // retain value of fields with #[type_foldable(identity)]
- bind.ast().attrs.iter().for_each(|x| {
- if !x.path().is_ident("type_foldable") {
- return;
- }
- let _ = x.parse_nested_meta(|nested| {
- if nested.path.is_ident("identity") {
- fixed = true;
- }
- Ok(())
- });
- });
-
- if fixed {
- bind.to_token_stream()
- } else {
- quote! {
- ::rustc_middle::ty::fold::TypeFoldable::try_fold_with(#bind, __folder)?
- }
+ quote! {
+ ::rustc_middle::ty::traverse::OptTryFoldWith::mk_try_fold_with()(#bind, __folder)?
  }
  })
  });

compiler/rustc_macros/src/type_visitable.rs

@@ -10,34 +10,30 @@ pub(super) fn type_visitable_derive(
 
  s.underscore_const(true);
 
- // ignore fields with #[type_visitable(ignore)]
- s.filter(|bi| {
- let mut ignored = false;
-
- bi.ast().attrs.iter().for_each(|attr| {
- if !attr.path().is_ident("type_visitable") {
- return;
- }
- let _ = attr.parse_nested_meta(|nested| {
- if nested.path.is_ident("ignore") {
- ignored = true;
- }
- Ok(())
- });
- });
-
- !ignored
- });
-
  if !s.ast().generics.lifetimes().any(|lt| lt.lifetime.ident == "tcx") {
  s.add_impl_generic(parse_quote! { 'tcx });
  }
 
- s.add_bounds(synstructure::AddBounds::Generics);
+ s.add_bounds(synstructure::AddBounds::None);
+ let mut where_clauses = None;
+ s.add_trait_bounds(
+ &parse_quote!(
+ ::rustc_middle::ty::traverse::OptVisitWith::<::rustc_middle::ty::TyCtxt<'tcx>>
+ ),
+ &mut where_clauses,
+ synstructure::AddBounds::Fields,
+ );
+ s.add_where_predicate(parse_quote! { Self: std::fmt::Debug + Clone });
+ for pred in where_clauses.into_iter().flat_map(|c| c.predicates) {
+ s.add_where_predicate(pred);
+ }
+
+ let impl_traversable_s = s.clone();
+
  let body_visit = s.each(|bind| {
  quote! {
  match ::rustc_ast_ir::visit::VisitorResult::branch(
- ::rustc_middle::ty::visit::TypeVisitable::visit_with(#bind, __visitor)
+ ::rustc_middle::ty::traverse::OptVisitWith::mk_visit_with()(#bind, __visitor)
  ) {
  ::core::ops::ControlFlow::Continue(()) => {},
  ::core::ops::ControlFlow::Break(r) => {
@@ -48,7 +44,7 @@ pub(super) fn type_visitable_derive(
  });
  s.bind_with(|_| synstructure::BindStyle::Move);
 
- s.bound_impl(
+ let visitable_impl = s.bound_impl(
  quote!(::rustc_middle::ty::visit::TypeVisitable<::rustc_middle::ty::TyCtxt<'tcx>>),
  quote! {
  fn visit_with<__V: ::rustc_middle::ty::visit::TypeVisitor<::rustc_middle::ty::TyCtxt<'tcx>>>(
@@ -59,5 +55,17 @@ pub(super) fn type_visitable_derive(
  <__V::Result as ::rustc_ast_ir::visit::VisitorResult>::output()
  }
  },
- )
+ );
+
+ let traversable_impl = impl_traversable_s.bound_impl(
+ quote!(::rustc_middle::ty::traverse::TypeTraversable<::rustc_middle::ty::TyCtxt<'tcx>>),
+ quote! {
+ type Kind = ::rustc_middle::ty::traverse::ImportantTypeTraversal;
+ },
+ );
+
+ quote! {
+ #visitable_impl
+ #traversable_impl
+ }
 }

compiler/rustc_middle/src/hir/place.rs

@@ -1,12 +1,14 @@
 use rustc_hir::HirId;
-use rustc_macros::{HashStable, TyDecodable, TyEncodable, TypeFoldable, TypeVisitable};
+use rustc_macros::{
+ HashStable, NoopTypeTraversable, TyDecodable, TyEncodable, TypeFoldable, TypeVisitable,
+};
 use rustc_target::abi::{FieldIdx, VariantIdx};
 
 use crate::ty;
 use crate::ty::Ty;
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable, HashStable)]
-#[derive(TypeFoldable, TypeVisitable)]
+#[derive(NoopTypeTraversable)]
 pub enum PlaceBase {
  /// A temporary variable.
  Rvalue,
@@ -19,7 +21,7 @@ pub enum PlaceBase {
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable, HashStable)]
-#[derive(TypeFoldable, TypeVisitable)]
+#[derive(NoopTypeTraversable)]
 pub enum ProjectionKind {
  /// A dereference of a pointer, reference or `Box<T>` of the given type.
  Deref,

compiler/rustc_middle/src/macros.rs

@@ -73,32 +73,8 @@ macro_rules! TrivialLiftImpls {
 macro_rules! TrivialTypeTraversalImpls {
  ($($ty:ty),+ $(,)?) => {
  $(
- impl<'tcx> $crate::ty::fold::TypeFoldable<$crate::ty::TyCtxt<'tcx>> for $ty {
- fn try_fold_with<F: $crate::ty::fold::FallibleTypeFolder<$crate::ty::TyCtxt<'tcx>>>(
- self,
- _: &mut F,
- ) -> ::std::result::Result<Self, F::Error> {
- Ok(self)
- }
-
- #[inline]
- fn fold_with<F: $crate::ty::fold::TypeFolder<$crate::ty::TyCtxt<'tcx>>>(
- self,
- _: &mut F,
- ) -> Self {
- self
- }
- }
-
- impl<'tcx> $crate::ty::visit::TypeVisitable<$crate::ty::TyCtxt<'tcx>> for $ty {
- #[inline]
- fn visit_with<F: $crate::ty::visit::TypeVisitor<$crate::ty::TyCtxt<'tcx>>>(
- &self,
- _: &mut F)
- -> F::Result
- {
- <F::Result as ::rustc_ast_ir::visit::VisitorResult>::output()
- }
+ impl<'tcx> $crate::ty::traverse::TypeTraversable<$crate::ty::TyCtxt<'tcx>> for $ty {
+ type Kind = $crate::ty::traverse::NoopTypeTraversal;
  }
  )+
  };

compiler/rustc_middle/src/mir/query.rs

@@ -57,8 +57,6 @@ pub struct CoroutineLayout<'tcx> {
  /// Which saved locals are storage-live at the same time. Locals that do not
  /// have conflicts with each other are allowed to overlap in the computed
  /// layout.
- #[type_foldable(identity)]
- #[type_visitable(ignore)]
  pub storage_conflicts: BitMatrix<CoroutineSavedLocal, CoroutineSavedLocal>,
 }