From 69890b2df447e7d3febff1a0f8974f3fcf694128 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Wed, 18 Jan 2023 23:21:12 +0000
Subject: trait solver: PointerSized

---
 .../rustc_trait_selection/src/solve/assembly.rs    |  7 ++++++
 .../src/solve/project_goals.rs                     |  7 ++++++
 .../rustc_trait_selection/src/solve/trait_goals.rs | 27 ++++++++++++++++++++--
 3 files changed, 39 insertions(+), 2 deletions(-)

(limited to 'compiler/rustc_trait_selection/src')

diff --git a/compiler/rustc_trait_selection/src/solve/assembly.rs b/compiler/rustc_trait_selection/src/solve/assembly.rs
index 45bce34b1ed..52155aa0f18 100644
--- a/compiler/rustc_trait_selection/src/solve/assembly.rs
+++ b/compiler/rustc_trait_selection/src/solve/assembly.rs
@@ -117,6 +117,11 @@ pub(super) trait GoalKind<'tcx>: TypeFoldable<'tcx> + Copy + Eq {
         ecx: &mut EvalCtxt<'_, 'tcx>,
         goal: Goal<'tcx, Self>,
     ) -> QueryResult<'tcx>;
+
+    fn consider_builtin_pointer_sized_candidate(
+        ecx: &mut EvalCtxt<'_, 'tcx>,
+        goal: Goal<'tcx, Self>,
+    ) -> QueryResult<'tcx>;
 }
 
 impl<'tcx> EvalCtxt<'_, 'tcx> {
@@ -237,6 +242,8 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
             || lang_items.clone_trait() == Some(trait_def_id)
         {
             G::consider_builtin_copy_clone_candidate(self, goal)
+        } else if lang_items.pointer_sized() == Some(trait_def_id) {
+            G::consider_builtin_pointer_sized_candidate(self, goal)
         } else {
             Err(NoSolution)
         };
diff --git a/compiler/rustc_trait_selection/src/solve/project_goals.rs b/compiler/rustc_trait_selection/src/solve/project_goals.rs
index ffc1c70e0cb..3f3d32efe7f 100644
--- a/compiler/rustc_trait_selection/src/solve/project_goals.rs
+++ b/compiler/rustc_trait_selection/src/solve/project_goals.rs
@@ -351,6 +351,13 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
     ) -> QueryResult<'tcx> {
         bug!("`Copy`/`Clone` does not have an associated type: {:?}", goal);
     }
+
+    fn consider_builtin_pointer_sized_candidate(
+        ecx: &mut EvalCtxt<'_, 'tcx>,
+        goal: Goal<'tcx, Self>,
+    ) -> QueryResult<'tcx> {
+        bug!("`PointerSized` does not have an associated type: {:?}", goal);
+    }
 }
 
 /// This behavior is also implemented in `rustc_ty_utils` and in the old `project` code.
diff --git a/compiler/rustc_trait_selection/src/solve/trait_goals.rs b/compiler/rustc_trait_selection/src/solve/trait_goals.rs
index 1ebcfd03c14..f68a296922a 100644
--- a/compiler/rustc_trait_selection/src/solve/trait_goals.rs
+++ b/compiler/rustc_trait_selection/src/solve/trait_goals.rs
@@ -4,13 +4,13 @@ use std::iter;
 
 use super::assembly::{self, Candidate, CandidateSource};
 use super::infcx_ext::InferCtxtExt;
-use super::{EvalCtxt, Goal, QueryResult};
+use super::{Certainty, EvalCtxt, Goal, QueryResult};
 use rustc_hir::def_id::DefId;
 use rustc_infer::infer::InferCtxt;
 use rustc_infer::traits::query::NoSolution;
 use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams};
-use rustc_middle::ty::TraitPredicate;
 use rustc_middle::ty::{self, Ty, TyCtxt};
+use rustc_middle::ty::{TraitPredicate, TypeVisitable};
 use rustc_span::DUMMY_SP;
 
 mod structural_traits;
@@ -127,6 +127,29 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
             structural_traits::instantiate_constituent_tys_for_copy_clone_trait,
         )
     }
+
+    fn consider_builtin_pointer_sized_candidate(
+        ecx: &mut EvalCtxt<'_, 'tcx>,
+        goal: Goal<'tcx, Self>,
+    ) -> QueryResult<'tcx> {
+        if goal.predicate.self_ty().has_non_region_infer() {
+            return ecx.make_canonical_response(Certainty::Maybe(MaybeCause::Ambiguity));
+        }
+
+        let tcx = ecx.tcx();
+        let self_ty = tcx.erase_regions(goal.predicate.self_ty());
+
+        if let Ok(layout) = tcx.layout_of(goal.param_env.and(self_ty))
+            &&  let usize_layout = tcx.layout_of(ty::ParamEnv::empty().and(tcx.types.usize)).unwrap().layout
+            && layout.layout.size() == usize_layout.size()
+            && layout.layout.align().abi == usize_layout.align().abi
+        {
+            // FIXME: We could make this faster by making a no-constraints response
+            ecx.make_canonical_response(Certainty::Yes)
+        } else {
+            Err(NoSolution)
+        }
+    }
 }
 
 impl<'tcx> EvalCtxt<'_, 'tcx> {
-- 
cgit 1.4.1-3-g733a5