trait_sel: `{Meta,Pointee}Sized` on `Sized` types

Introduce the `MetaSized` and `PointeeSized` traits as supertraits of
`Sized` and initially implement it on everything that currently
implements `Sized` to isolate any changes that simply adding the
traits introduces.

4 files changed, 82 insertions, 0 deletions

diff --git a/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs b/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs
index 0c267feefbe..434e2a818bd 100644
--- a/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs
@@ -212,6 +212,24 @@ where
         goal: Goal<I, Self>,
     ) -> Result<Candidate<I>, NoSolution>;
 
+    /// A type is `MetaSized` if its tail component is `MetaSized`.
+    ///
+    /// These components are given by built-in rules from
+    /// [`structural_traits::instantiate_constituent_tys_for_sized_trait`].
+    fn consider_builtin_meta_sized_candidate(
+        ecx: &mut EvalCtxt<'_, D>,
+        goal: Goal<I, Self>,
+    ) -> Result<Candidate<I>, NoSolution>;
+
+    /// A type is `PointeeSized` if its tail component is `PointeeSized`.
+    ///
+    /// These components are given by built-in rules from
+    /// [`structural_traits::instantiate_constituent_tys_for_sized_trait`].
+    fn consider_builtin_pointee_sized_candidate(
+        ecx: &mut EvalCtxt<'_, D>,
+        goal: Goal<I, Self>,
+    ) -> Result<Candidate<I>, NoSolution>;
+
     /// A type is `Copy` or `Clone` if its components are `Copy` or `Clone`.
     ///
     /// These components are given by built-in rules from
@@ -467,6 +485,12 @@ where
         } else {
             match cx.as_lang_item(trait_def_id) {
                 Some(TraitSolverLangItem::Sized) => G::consider_builtin_sized_candidate(self, goal),
+                Some(TraitSolverLangItem::MetaSized) => {
+                    G::consider_builtin_meta_sized_candidate(self, goal)
+                }
+                Some(TraitSolverLangItem::PointeeSized) => {
+                    G::consider_builtin_pointee_sized_candidate(self, goal)
+                }
                 Some(TraitSolverLangItem::Copy | TraitSolverLangItem::Clone) => {
                     G::consider_builtin_copy_clone_candidate(self, goal)
                 }
diff --git a/compiler/rustc_next_trait_solver/src/solve/effect_goals.rs b/compiler/rustc_next_trait_solver/src/solve/effect_goals.rs
index 8413c2abbb9..dda00a0a2c5 100644
--- a/compiler/rustc_next_trait_solver/src/solve/effect_goals.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/effect_goals.rs
@@ -205,6 +205,20 @@ where
         unreachable!("Sized is never const")
     }
 
+    fn consider_builtin_meta_sized_candidate(
+        _ecx: &mut EvalCtxt<'_, D>,
+        _goal: Goal<I, Self>,
+    ) -> Result<Candidate<I>, NoSolution> {
+        unreachable!("MetaSized is never const")
+    }
+
+    fn consider_builtin_pointee_sized_candidate(
+        _ecx: &mut EvalCtxt<'_, D>,
+        _goal: Goal<I, Self>,
+    ) -> Result<Candidate<I>, NoSolution> {
+        unreachable!("PointeeSized is never const")
+    }
+
     fn consider_builtin_copy_clone_candidate(
         _ecx: &mut EvalCtxt<'_, D>,
         _goal: Goal<I, Self>,
diff --git a/compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs b/compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs
index 2fddc0044cb..42aeb170d6b 100644
--- a/compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs
@@ -420,6 +420,20 @@ where
         panic!("`Sized` does not have an associated type: {:?}", goal);
     }
 
+    fn consider_builtin_meta_sized_candidate(
+        _ecx: &mut EvalCtxt<'_, D>,
+        goal: Goal<I, Self>,
+    ) -> Result<Candidate<I>, NoSolution> {
+        panic!("`MetaSized` does not have an associated type: {:?}", goal);
+    }
+
+    fn consider_builtin_pointee_sized_candidate(
+        _ecx: &mut EvalCtxt<'_, D>,
+        goal: Goal<I, Self>,
+    ) -> Result<Candidate<I>, NoSolution> {
+        panic!("`PointeeSized` does not have an associated type: {:?}", goal);
+    }
+
     fn consider_builtin_copy_clone_candidate(
         _ecx: &mut EvalCtxt<'_, D>,
         goal: Goal<I, Self>,
diff --git a/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs b/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs
index 110c67a8e21..50a7647be62 100644
--- a/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs
@@ -260,6 +260,36 @@ where
         )
     }
 
+    fn consider_builtin_meta_sized_candidate(
+        ecx: &mut EvalCtxt<'_, D>,
+        goal: Goal<I, Self>,
+    ) -> Result<Candidate<I>, NoSolution> {
+        if goal.predicate.polarity != ty::PredicatePolarity::Positive {
+            return Err(NoSolution);
+        }
+
+        ecx.probe_and_evaluate_goal_for_constituent_tys(
+            CandidateSource::BuiltinImpl(BuiltinImplSource::Misc),
+            goal,
+            structural_traits::instantiate_constituent_tys_for_sized_trait,
+        )
+    }
+
+    fn consider_builtin_pointee_sized_candidate(
+        ecx: &mut EvalCtxt<'_, D>,
+        goal: Goal<I, Self>,
+    ) -> Result<Candidate<I>, NoSolution> {
+        if goal.predicate.polarity != ty::PredicatePolarity::Positive {
+            return Err(NoSolution);
+        }
+
+        ecx.probe_and_evaluate_goal_for_constituent_tys(
+            CandidateSource::BuiltinImpl(BuiltinImplSource::Misc),
+            goal,
+            structural_traits::instantiate_constituent_tys_for_sized_trait,
+        )
+    }
+
     fn consider_builtin_copy_clone_candidate(
         ecx: &mut EvalCtxt<'_, D>,
         goal: Goal<I, Self>,