Rollup merge of rust-lang#121703 - compiler-errors:new, r=lcnr

Add a way to add constructors for `rustc_type_ir` types

Introduces a module called `rustc_type_ir`, in which we can place traits which are named `Ty`/`Region`/`Const`/etc. which expose constructors for the `rustc_type_ir` types. This means we can construct things `Interner::Ty` with `Ty::new_x(...)`, which is needed to uplift the new trait solver into an interner-agnostic crate.

These traits are placed into a *separate* module because they're only intended to be used in interner-agnostic code, and they should mirror the constructors that are provided by the inherent constructor methods in `rustc_middle`.

Putting this up for vibe-check mostly. I haven't copied over any of the type constructors, except for one to create bound types for use in the canonicalizer.

r? lcnr

compiler/rustc_middle/src/ty/consts.rs

@@ -175,7 +175,20 @@ impl<'tcx> Const<'tcx> {
         let reported = tcx.dcx().span_delayed_bug(span, msg);
         Const::new_error(tcx, reported, ty)
     }
+}
 
+impl<'tcx> rustc_type_ir::new::Const<TyCtxt<'tcx>> for Const<'tcx> {
+    fn new_anon_bound(
+        tcx: TyCtxt<'tcx>,
+        debruijn: ty::DebruijnIndex,
+        var: ty::BoundVar,
+        ty: Ty<'tcx>,
+    ) -> Self {
+        Const::new_bound(tcx, debruijn, var, ty)
+    }
+}
+
+impl<'tcx> Const<'tcx> {
     /// Literals and const generic parameters are eagerly converted to a constant, everything else
     /// becomes `Unevaluated`.
     #[instrument(skip(tcx), level = "debug")]

compiler/rustc_middle/src/ty/context.rs

@@ -130,27 +130,6 @@ impl<'tcx> Interner for TyCtxt<'tcx> {
     fn mk_canonical_var_infos(self, infos: &[ty::CanonicalVarInfo<Self>]) -> Self::CanonicalVars {
         self.mk_canonical_var_infos(infos)
     }
-
-    fn mk_bound_ty(self, debruijn: ty::DebruijnIndex, var: ty::BoundVar) -> Self::Ty {
-        Ty::new_bound(self, debruijn, ty::BoundTy { var, kind: ty::BoundTyKind::Anon })
-    }
-
-    fn mk_bound_region(self, debruijn: ty::DebruijnIndex, var: ty::BoundVar) -> Self::Region {
-        Region::new_bound(
-            self,
-            debruijn,
-            ty::BoundRegion { var, kind: ty::BoundRegionKind::BrAnon },
-        )
-    }
-
-    fn mk_bound_const(
-        self,
-        debruijn: ty::DebruijnIndex,
-        var: ty::BoundVar,
-        ty: Self::Ty,
-    ) -> Self::Const {
-        Const::new_bound(self, debruijn, var, ty)
-    }
 }
 
 type InternedSet<'tcx, T> = ShardedHashMap<InternedInSet<'tcx, T>, ()>;

compiler/rustc_middle/src/ty/region.rs

@@ -136,6 +136,12 @@ impl<'tcx> Region<'tcx> {
     }
 }
 
+impl<'tcx> rustc_type_ir::new::Region<TyCtxt<'tcx>> for Region<'tcx> {
+    fn new_anon_bound(tcx: TyCtxt<'tcx>, debruijn: ty::DebruijnIndex, var: ty::BoundVar) -> Self {
+        Region::new_bound(tcx, debruijn, ty::BoundRegion { var, kind: ty::BoundRegionKind::BrAnon })
+    }
+}
+
 /// Region utilities
 impl<'tcx> Region<'tcx> {
     pub fn kind(self) -> RegionKind<'tcx> {

compiler/rustc_middle/src/ty/sty.rs

@@ -1426,7 +1426,8 @@ impl From<BoundVar> for BoundTy {
 
 /// Constructors for `Ty`
 impl<'tcx> Ty<'tcx> {
-    // Avoid this in favour of more specific `new_*` methods, where possible.
+    /// Avoid using this in favour of more specific `new_*` methods, where possible.
+    /// The more specific methods will often optimize their creation.
     #[allow(rustc::usage_of_ty_tykind)]
     #[inline]
     pub fn new(tcx: TyCtxt<'tcx>, st: TyKind<'tcx>) -> Ty<'tcx> {
@@ -1813,6 +1814,12 @@ impl<'tcx> Ty<'tcx> {
     }
 }
 
+impl<'tcx> rustc_type_ir::new::Ty<TyCtxt<'tcx>> for Ty<'tcx> {
+    fn new_anon_bound(tcx: TyCtxt<'tcx>, debruijn: ty::DebruijnIndex, var: ty::BoundVar) -> Self {
+        Ty::new_bound(tcx, debruijn, ty::BoundTy { var, kind: ty::BoundTyKind::Anon })
+    }
+}
+
 /// Type utilities
 impl<'tcx> Ty<'tcx> {
     #[inline(always)]

compiler/rustc_next_trait_solver/src/canonicalizer.rs

@@ -1,6 +1,7 @@
 use std::cmp::Ordering;
 
 use rustc_type_ir::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
+use rustc_type_ir::new::{Const, Region, Ty};
 use rustc_type_ir::visit::TypeVisitableExt;
 use rustc_type_ir::{
     self as ty, Canonical, CanonicalTyVarKind, CanonicalVarInfo, CanonicalVarKind, ConstTy,
@@ -293,7 +294,7 @@ impl<Infcx: InferCtxtLike<Interner = I>, I: Interner> TypeFolder<I>
             var
         });
 
-        self.interner().mk_bound_region(self.binder_index, var)
+        Region::new_anon_bound(self.interner(), self.binder_index, var)
     }
 
     fn fold_ty(&mut self, t: I::Ty) -> I::Ty
@@ -375,7 +376,7 @@ impl<Infcx: InferCtxtLike<Interner = I>, I: Interner> TypeFolder<I>
             }),
         );
 
-        self.interner().mk_bound_ty(self.binder_index, var)
+        Ty::new_anon_bound(self.interner(), self.binder_index, var)
     }
 
     fn fold_const(&mut self, c: I::Const) -> I::Const
@@ -435,6 +436,6 @@ impl<Infcx: InferCtxtLike<Interner = I>, I: Interner> TypeFolder<I>
             }),
         );
 
-        self.interner().mk_bound_const(self.binder_index, var, c.ty())
+        Const::new_anon_bound(self.interner(), self.binder_index, var, c.ty())
     }
 }

compiler/rustc_type_ir/src/interner.rs

@@ -4,8 +4,8 @@ use std::hash::Hash;
 
 use crate::visit::{Flags, TypeSuperVisitable, TypeVisitable};
 use crate::{
-    BoundVar, BoundVars, CanonicalVarInfo, ConstKind, DebruijnIndex, DebugWithInfcx, RegionKind,
-    TyKind, UniverseIndex,
+    new, BoundVar, BoundVars, CanonicalVarInfo, ConstKind, DebugWithInfcx, RegionKind, TyKind,
+    UniverseIndex,
 };
 
 pub trait Interner: Sized {
@@ -34,7 +34,8 @@ pub trait Interner: Sized {
         + Into<Self::GenericArg>
         + IntoKind<Kind = TyKind<Self>>
         + TypeSuperVisitable<Self>
-        + Flags;
+        + Flags
+        + new::Ty<Self>;
     type Tys: Copy + Debug + Hash + Ord + IntoIterator<Item = Self::Ty>;
     type AliasTy: Copy + DebugWithInfcx<Self> + Hash + Ord;
     type ParamTy: Copy + Debug + Hash + Ord;
@@ -56,7 +57,8 @@ pub trait Interner: Sized {
         + IntoKind<Kind = ConstKind<Self>>
         + ConstTy<Self>
         + TypeSuperVisitable<Self>
-        + Flags;
+        + Flags
+        + new::Const<Self>;
     type AliasConst: Copy + DebugWithInfcx<Self> + Hash + Ord;
     type PlaceholderConst: Copy + Debug + Hash + Ord + PlaceholderLike;
     type ParamConst: Copy + Debug + Hash + Ord;
@@ -71,7 +73,8 @@ pub trait Interner: Sized {
         + Ord
         + Into<Self::GenericArg>
         + IntoKind<Kind = RegionKind<Self>>
-        + Flags;
+        + Flags
+        + new::Region<Self>;
     type EarlyParamRegion: Copy + Debug + Hash + Ord;
     type LateParamRegion: Copy + Debug + Hash + Ord;
     type BoundRegion: Copy + Debug + Hash + Ord;
@@ -90,11 +93,6 @@ pub trait Interner: Sized {
     type ClosureKind: Copy + Debug + Hash + Eq;
 
     fn mk_canonical_var_infos(self, infos: &[CanonicalVarInfo<Self>]) -> Self::CanonicalVars;
-
-    // FIXME: We should not have all these constructors on `Interner`, but as functions on some trait.
-    fn mk_bound_ty(self, debruijn: DebruijnIndex, var: BoundVar) -> Self::Ty;
-    fn mk_bound_region(self, debruijn: DebruijnIndex, var: BoundVar) -> Self::Region;
-    fn mk_bound_const(self, debruijn: DebruijnIndex, var: BoundVar, ty: Self::Ty) -> Self::Const;
 }
 
 /// Common capabilities of placeholder kinds

compiler/rustc_type_ir/src/lib.rs

@@ -24,6 +24,7 @@ use std::sync::Arc as Lrc;
 #[cfg(feature = "nightly")]
 pub mod codec;
 pub mod fold;
+pub mod new;
 pub mod ty_info;
 pub mod ty_kind;
 pub mod visit;

compiler/rustc_type_ir/src/new.rs

@@ -0,0 +1,13 @@
+use crate::{BoundVar, DebruijnIndex, Interner};
+
+pub trait Ty<I: Interner<Ty = Self>> {
+    fn new_anon_bound(interner: I, debruijn: DebruijnIndex, var: BoundVar) -> Self;
+}
+
+pub trait Region<I: Interner<Region = Self>> {
+    fn new_anon_bound(interner: I, debruijn: DebruijnIndex, var: BoundVar) -> Self;
+}
+
+pub trait Const<I: Interner<Const = Self>> {
+    fn new_anon_bound(interner: I, debruijn: DebruijnIndex, var: BoundVar, ty: I::Ty) -> Self;
+}