do not relate Abi and Safety

and update some macros while we're at it

compiler/rustc_middle/src/ty/relate.rs

@@ -1,7 +1,5 @@
 use std::iter;
 
-use rustc_hir as hir;
-use rustc_target::spec::abi;
 pub use rustc_type_ir::relate::*;
 
 use crate::ty::error::{ExpectedFound, TypeError};
@@ -121,26 +119,6 @@ fn relate<R: TypeRelation<TyCtxt<'tcx>>>(
     }
 }
 
-impl<'tcx> Relate<TyCtxt<'tcx>> for hir::Safety {
-    fn relate<R: TypeRelation<TyCtxt<'tcx>>>(
-        _relation: &mut R,
-        a: hir::Safety,
-        b: hir::Safety,
-    ) -> RelateResult<'tcx, hir::Safety> {
-        if a != b { Err(TypeError::SafetyMismatch(ExpectedFound::new(true, a, b))) } else { Ok(a) }
-    }
-}
-
-impl<'tcx> Relate<TyCtxt<'tcx>> for abi::Abi {
-    fn relate<R: TypeRelation<TyCtxt<'tcx>>>(
-        _relation: &mut R,
-        a: abi::Abi,
-        b: abi::Abi,
-    ) -> RelateResult<'tcx, abi::Abi> {
-        if a == b { Ok(a) } else { Err(TypeError::AbiMismatch(ExpectedFound::new(true, a, b))) }
-    }
-}
-
 impl<'tcx> Relate<TyCtxt<'tcx>> for ty::GenericArgsRef<'tcx> {
     fn relate<R: TypeRelation<TyCtxt<'tcx>>>(
         relation: &mut R,

compiler/rustc_middle/src/ty/structural_impls.rs

@@ -264,8 +264,6 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 // interners).
 TrivialTypeTraversalAndLiftImpls! {
     ::rustc_hir::def_id::DefId,
-    ::rustc_hir::Safety,
-    ::rustc_target::spec::abi::Abi,
     crate::ty::ClosureKind,
     crate::ty::ParamConst,
     crate::ty::ParamTy,
@@ -276,6 +274,11 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
     rustc_target::abi::Size,
 }
 
+TrivialLiftImpls! {
+    ::rustc_hir::Safety,
+    ::rustc_target::spec::abi::Abi,
+}
+
 ///////////////////////////////////////////////////////////////////////////
 // Lift implementations
 

compiler/rustc_type_ir/src/error.rs

@@ -29,8 +29,8 @@ pub enum TypeError<I: Interner> {
     Mismatch,
     ConstnessMismatch(ExpectedFound<ty::BoundConstness>),
     PolarityMismatch(ExpectedFound<ty::PredicatePolarity>),
-    SafetyMismatch(ExpectedFound<I::Safety>),
+    SafetyMismatch(#[type_visitable(ignore)] ExpectedFound<I::Safety>),
-    AbiMismatch(ExpectedFound<I::Abi>),
+    AbiMismatch(#[type_visitable(ignore)] ExpectedFound<I::Abi>),
     Mutability,
     ArgumentMutability(usize),
     TupleSize(ExpectedFound<usize>),

compiler/rustc_type_ir/src/inherent.rs

@@ -208,14 +208,14 @@ pub trait Tys<I: Interner<Tys = Self>>:
     fn output(self) -> I::Ty;
 }
 
-pub trait Abi<I: Interner<Abi = Self>>: Copy + Debug + Hash + Eq + Relate<I> {
+pub trait Abi<I: Interner<Abi = Self>>: Copy + Debug + Hash + Eq {
     fn rust() -> Self;
 
     /// Whether this ABI is `extern "Rust"`.
     fn is_rust(self) -> bool;
 }
 
-pub trait Safety<I: Interner<Safety = Self>>: Copy + Debug + Hash + Eq + Relate<I> {
+pub trait Safety<I: Interner<Safety = Self>>: Copy + Debug + Hash + Eq {
     fn safe() -> Self;
 
     fn is_safe(self) -> bool;

compiler/rustc_type_ir/src/relate.rs

@@ -174,12 +174,17 @@ fn relate<R: TypeRelation<I>>(
                 ExpectedFound::new(true, a, b)
             }));
         }
-        let safety = relation.relate(a.safety, b.safety)?;
+
-        let abi = relation.relate(a.abi, b.abi)?;
+        if a.safety != b.safety {
+            return Err(TypeError::SafetyMismatch(ExpectedFound::new(true, a.safety, b.safety)));
+        }
+
+        if a.abi != b.abi {
+            return Err(TypeError::AbiMismatch(ExpectedFound::new(true, a.abi, b.abi)));
+        };
 
         let a_inputs = a.inputs();
         let b_inputs = b.inputs();
-
         if a_inputs.len() != b_inputs.len() {
             return Err(TypeError::ArgCount);
         }
@@ -212,8 +217,8 @@ fn relate<R: TypeRelation<I>>(
         Ok(ty::FnSig {
             inputs_and_output: cx.mk_type_list_from_iter(inputs_and_output)?,
             c_variadic: a.c_variadic,
-            safety,
+            safety: a.safety,
-            abi,
+            abi: a.abi,
         })
     }
 }

compiler/rustc_type_ir/src/ty_kind.rs

@@ -861,7 +861,11 @@ pub struct TypeAndMut<I: Interner> {
 pub struct FnSig<I: Interner> {
     pub inputs_and_output: I::Tys,
     pub c_variadic: bool,
+    #[type_visitable(ignore)]
+    #[type_foldable(identity)]
     pub safety: I::Safety,
+    #[type_visitable(ignore)]
+    #[type_foldable(identity)]
     pub abi: I::Abi,
 }
 

compiler/rustc_type_ir/src/ty_kind/closure.rs

@@ -372,8 +372,12 @@ pub struct CoroutineClosureSignature<I: Interner> {
     /// Always false
     pub c_variadic: bool,
     /// Always `Normal` (safe)
+    #[type_visitable(ignore)]
+    #[type_foldable(identity)]
     pub safety: I::Safety,
     /// Always `RustCall`
+    #[type_visitable(ignore)]
+    #[type_foldable(identity)]
     pub abi: I::Abi,
 }
 

compiler/rustc_type_ir_macros/src/lib.rs

@@ -1,18 +1,73 @@
-use quote::quote;
+use quote::{ToTokens, quote};
-use syn::parse_quote;
 use syn::visit_mut::VisitMut;
+use syn::{Attribute, parse_quote};
 use synstructure::decl_derive;
 
 decl_derive!(
-    [TypeFoldable_Generic] => type_foldable_derive
+    [TypeVisitable_Generic, attributes(type_visitable)] => type_visitable_derive
 );
 decl_derive!(
-    [TypeVisitable_Generic] => type_visitable_derive
+    [TypeFoldable_Generic, attributes(type_foldable)] => type_foldable_derive
 );
 decl_derive!(
     [Lift_Generic] => lift_derive
 );
 
+fn has_ignore_attr(attrs: &[Attribute], name: &'static str, meta: &'static str) -> bool {
+    let mut ignored = false;
+    attrs.iter().for_each(|attr| {
+        if !attr.path().is_ident(name) {
+            return;
+        }
+        let _ = attr.parse_nested_meta(|nested| {
+            if nested.path.is_ident(meta) {
+                ignored = true;
+            }
+            Ok(())
+        });
+    });
+
+    ignored
+}
+
+fn type_visitable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
+    if let syn::Data::Union(_) = s.ast().data {
+        panic!("cannot derive on union")
+    }
+
+    if !s.ast().generics.type_params().any(|ty| ty.ident == "I") {
+        s.add_impl_generic(parse_quote! { I });
+    }
+
+    s.filter(|bi| !has_ignore_attr(&bi.ast().attrs, "type_visitable", "ignore"));
+
+    s.add_where_predicate(parse_quote! { I: Interner });
+    s.add_bounds(synstructure::AddBounds::Fields);
+    let body_visit = s.each(|bind| {
+        quote! {
+            match ::rustc_ast_ir::visit::VisitorResult::branch(
+                ::rustc_type_ir::visit::TypeVisitable::visit_with(#bind, __visitor)
+            ) {
+                ::core::ops::ControlFlow::Continue(()) => {},
+                ::core::ops::ControlFlow::Break(r) => {
+                    return ::rustc_ast_ir::visit::VisitorResult::from_residual(r);
+                },
+            }
+        }
+    });
+    s.bind_with(|_| synstructure::BindStyle::Move);
+
+    s.bound_impl(quote!(::rustc_type_ir::visit::TypeVisitable<I>), quote! {
+        fn visit_with<__V: ::rustc_type_ir::visit::TypeVisitor<I>>(
+            &self,
+            __visitor: &mut __V
+        ) -> __V::Result {
+            match *self { #body_visit }
+            <__V::Result as ::rustc_ast_ir::visit::VisitorResult>::output()
+        }
+    })
+}
+
 fn type_foldable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
     if let syn::Data::Union(_) = s.ast().data {
         panic!("cannot derive on union")
@@ -29,12 +84,23 @@ fn type_foldable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::Toke
         let bindings = vi.bindings();
         vi.construct(|_, index| {
             let bind = &bindings[index];
-            quote! {
+
-                ::rustc_type_ir::fold::TypeFoldable::try_fold_with(#bind, __folder)?
+            // retain value of fields with #[type_foldable(identity)]
+            if has_ignore_attr(&bind.ast().attrs, "type_foldable", "identity") {
+                bind.to_token_stream()
+            } else {
+                quote! {
+                    ::rustc_type_ir::fold::TypeFoldable::try_fold_with(#bind, __folder)?
+                }
             }
         })
     });
 
+    // We filter fields which get ignored and don't require them to implement
+    // `TypeFoldable`. We do so after generating `body_fold` as we still need
+    // to generate code for them.
+    s.filter(|bi| !has_ignore_attr(&bi.ast().attrs, "type_foldable", "identity"));
+    s.add_bounds(synstructure::AddBounds::Fields);
     s.bound_impl(quote!(::rustc_type_ir::fold::TypeFoldable<I>), quote! {
         fn try_fold_with<__F: ::rustc_type_ir::fold::FallibleTypeFolder<I>>(
             self,
@@ -113,39 +179,3 @@ fn visit_type_path_mut(&mut self, i: &mut syn::TypePath) {
 
     ty
 }
-
-fn type_visitable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
-    if let syn::Data::Union(_) = s.ast().data {
-        panic!("cannot derive on union")
-    }
-
-    if !s.ast().generics.type_params().any(|ty| ty.ident == "I") {
-        s.add_impl_generic(parse_quote! { I });
-    }
-
-    s.add_where_predicate(parse_quote! { I: Interner });
-    s.add_bounds(synstructure::AddBounds::Fields);
-    let body_visit = s.each(|bind| {
-        quote! {
-            match ::rustc_ast_ir::visit::VisitorResult::branch(
-                ::rustc_type_ir::visit::TypeVisitable::visit_with(#bind, __visitor)
-            ) {
-                ::core::ops::ControlFlow::Continue(()) => {},
-                ::core::ops::ControlFlow::Break(r) => {
-                    return ::rustc_ast_ir::visit::VisitorResult::from_residual(r);
-                },
-            }
-        }
-    });
-    s.bind_with(|_| synstructure::BindStyle::Move);
-
-    s.bound_impl(quote!(::rustc_type_ir::visit::TypeVisitable<I>), quote! {
-        fn visit_with<__V: ::rustc_type_ir::visit::TypeVisitor<I>>(
-            &self,
-            __visitor: &mut __V
-        ) -> __V::Result {
-            match *self { #body_visit }
-            <__V::Result as ::rustc_ast_ir::visit::VisitorResult>::output()
-        }
-    })
-}