Fix some TODOs

compiler/rustc_infer/src/infer/mod.rs

@@ -368,6 +368,14 @@ impl<'tcx> ty::InferCtxtLike for InferCtxt<'tcx> {
         }
     }
 
+    fn root_ty_var(&self, var: TyVid) -> TyVid {
+        self.root_var(var)
+    }
+
+    fn root_const_var(&self, var: ConstVid) -> ConstVid {
+        self.root_const_var(var)
+    }
+
     fn opportunistic_resolve_ty_var(&self, vid: TyVid) -> Ty<'tcx> {
         match self.probe_ty_var(vid) {
             Ok(ty) => ty,

compiler/rustc_middle/src/ty/context.rs

@@ -324,12 +324,20 @@ impl<'tcx> Interner for TyCtxt<'tcx> {
 }
 
 impl<'tcx> rustc_type_ir::inherent::Abi<TyCtxt<'tcx>> for abi::Abi {
+    fn rust() -> Self {
+        abi::Abi::Rust
+    }
+
     fn is_rust(self) -> bool {
         matches!(self, abi::Abi::Rust)
     }
 }
 
 impl<'tcx> rustc_type_ir::inherent::Safety<TyCtxt<'tcx>> for hir::Safety {
+    fn safe() -> Self {
+        hir::Safety::Safe
+    }
+
     fn is_safe(self) -> bool {
         matches!(self, hir::Safety::Safe)
     }

compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs

@@ -18,6 +18,7 @@ use rustc_span::DUMMY_SP;
 use rustc_type_ir::fold::TypeSuperFoldable;
 use rustc_type_ir::inherent::*;
 use rustc_type_ir::relate::Relate;
+use rustc_type_ir::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitor};
 use rustc_type_ir::{self as ir, CanonicalVarValues, Interner};
 use rustc_type_ir_macros::{Lift_Generic, TypeFoldable_Generic, TypeVisitable_Generic};
 use std::ops::ControlFlow;
@@ -634,7 +635,6 @@ impl<Infcx: InferCtxtLike<Interner = I>, I: Interner> EvalCtxt<'_, Infcx> {
         }
     }
 
-    /* TODO:
     /// Is the projection predicate is of the form `exists<T> <Ty as Trait>::Assoc = T`.
     ///
     /// This is the case if the `term` does not occur in any other part of the predicate
@@ -685,8 +685,8 @@ impl<Infcx: InferCtxtLike<Interner = I>, I: Interner> EvalCtxt<'_, Infcx> {
                 match t.kind() {
                     ir::Infer(ir::TyVar(vid)) => {
                         if let ir::TermKind::Ty(term) = self.term.kind()
-                            && let Some(term_vid) = term.ty_vid()
-                            && self.infcx.root_var(vid) == self.infcx.root_var(term_vid)
+                            && let ir::Infer(ir::TyVar(term_vid)) = term.kind()
+                            && self.infcx.root_ty_var(vid) == self.infcx.root_ty_var(term_vid)
                         {
                             ControlFlow::Break(())
                         } else {
@@ -736,7 +736,6 @@ impl<Infcx: InferCtxtLike<Interner = I>, I: Interner> EvalCtxt<'_, Infcx> {
         goal.predicate.alias.visit_with(&mut visitor).is_continue()
             && goal.param_env.visit_with(&mut visitor).is_continue()
     }
-    */
 
     #[instrument(level = "trace", skip(self, param_env), ret)]
     pub(super) fn eq<T: Relate<I>>(

compiler/rustc_trait_selection/src/solve/normalizes_to/mod.rs

@@ -31,7 +31,7 @@ impl<'tcx> EvalCtxt<'_, InferCtxt<'tcx>> {
         goal: Goal<'tcx, NormalizesTo<'tcx>>,
     ) -> QueryResult<'tcx> {
         self.set_is_normalizes_to_goal();
-        // debug_assert!(self.term_is_fully_unconstrained(goal)); TODO:
+        debug_assert!(self.term_is_fully_unconstrained(goal));
         let normalize_result = self
             .probe(|&result| ProbeKind::TryNormalizeNonRigid { result })
             .enter(|this| this.normalize_at_least_one_step(goal));

compiler/rustc_type_ir/src/infcx.rs

@@ -12,6 +12,9 @@ pub trait InferCtxtLike: Sized {
     fn universe_of_lt(&self, lt: ty::RegionVid) -> Option<ty::UniverseIndex>;
     fn universe_of_ct(&self, ct: ty::ConstVid) -> Option<ty::UniverseIndex>;
 
+    fn root_ty_var(&self, var: ty::TyVid) -> ty::TyVid;
+    fn root_const_var(&self, var: ty::ConstVid) -> ty::ConstVid;
+
     fn opportunistic_resolve_ty_var(&self, vid: ty::TyVid) -> <Self::Interner as Interner>::Ty;
     fn opportunistic_resolve_int_var(&self, vid: ty::IntVid) -> <Self::Interner as Interner>::Ty;
     fn opportunistic_resolve_float_var(

compiler/rustc_type_ir/src/inherent.rs

@@ -111,7 +111,19 @@ pub trait Ty<I: Interner<Ty = Self>>:
         match self.kind() {
             ty::FnPtr(sig) => sig,
             ty::FnDef(def_id, args) => interner.fn_sig(def_id).instantiate(interner, &args),
-            _ => todo!("TODO:"),
+            ty::Error(_) => {
+                // ignore errors (#54954)
+                ty::Binder::dummy(ty::FnSig {
+                    inputs_and_output: Default::default(),
+                    c_variadic: false,
+                    safety: I::Safety::safe(),
+                    abi: I::Abi::rust(),
+                })
+            }
+            ty::Closure(..) => panic!(
+                "to get the signature of a closure, use `args.as_closure().sig()` not `fn_sig()`",
+            ),
+            _ => panic!("Ty::fn_sig() called on non-fn type: {:?}", self),
         }
     }
 }
@@ -129,12 +141,16 @@ pub trait Tys<I: Interner<Tys = Self>>:
     fn split_inputs_and_output(self) -> (I::FnInputTys, I::Ty);
 }
 
-pub trait Abi<I: Interner<Abi = Self>>: Copy + Debug + Hash + Eq + TypeVisitable<I> {
+pub trait Abi<I: Interner<Abi = Self>>: Copy + Debug + Hash + Eq + Relate<I> {
+    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 + TypeVisitable<I> {
+pub trait Safety<I: Interner<Safety = Self>>: Copy + Debug + Hash + Eq + Relate<I> {
+    fn safe() -> Self;
+
     fn is_safe(self) -> bool;
 
     fn prefix_str(self) -> &'static str;

compiler/rustc_type_ir/src/interner.rs

@@ -72,8 +72,8 @@ pub trait Interner:
         + IntoIterator<Item = ty::Binder<Self, ty::ExistentialPredicate<Self>>>;
     type AllocId: Copy + Debug + Hash + Eq;
     type Pat: Copy + Debug + Hash + Eq + Debug + Relate<Self>;
-    type Safety: Safety<Self> + TypeFoldable<Self> + Relate<Self>;
-    type Abi: Abi<Self> + TypeFoldable<Self> + Relate<Self>;
+    type Safety: Safety<Self>;
+    type Abi: Abi<Self>;
 
     // Kinds of consts
     type Const: Const<Self>;