Auto merge of #109413 - compiler-errors:pointer-like-abi, r=cjgillot

Enforce that `PointerLike` requires a pointer-like ABI

At least temporarily, let's ban coercing things that are pointer-sized and pointer-aligned but *not* `Abi::Scalar(..)` into `dyn*`. See: https://github.com/rust-lang/rust/pull/104694#discussion_r1142522073

This can be lifted in the future if we decie that we *want* to be able to coerce something `repr(C)` into a `dyn*`, but we'll have to figure out what to do with Miri and codegen...

r? compiler

1 files changed, 7 insertions, 8 deletions

diff --git a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
index 090312338e0..a794d20d683 100644
--- a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
@@ -97,7 +97,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             } else if lang_items.tuple_trait() == Some(def_id) {
                 self.assemble_candidate_for_tuple(obligation, &mut candidates);
             } else if lang_items.pointer_like() == Some(def_id) {
-                self.assemble_candidate_for_ptr_sized(obligation, &mut candidates);
+                self.assemble_candidate_for_pointer_like(obligation, &mut candidates);
             } else if lang_items.fn_ptr_trait() == Some(def_id) {
                 self.assemble_candidates_for_fn_ptr_trait(obligation, &mut candidates);
             } else {
@@ -942,15 +942,15 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         }
     }
 
-    fn assemble_candidate_for_ptr_sized(
+    fn assemble_candidate_for_pointer_like(
         &mut self,
         obligation: &TraitObligation<'tcx>,
         candidates: &mut SelectionCandidateSet<'tcx>,
     ) {
         // The regions of a type don't affect the size of the type
-        let self_ty = self
-            .tcx()
-            .erase_regions(self.tcx().erase_late_bound_regions(obligation.predicate.self_ty()));
+        let tcx = self.tcx();
+        let self_ty =
+            tcx.erase_regions(tcx.erase_late_bound_regions(obligation.predicate.self_ty()));
 
         // But if there are inference variables, we have to wait until it's resolved.
         if self_ty.has_non_region_infer() {
@@ -958,9 +958,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             return;
         }
 
-        if let Ok(layout) = self.tcx().layout_of(obligation.param_env.and(self_ty))
-            && layout.layout.size() == self.tcx().data_layout.pointer_size
-            && layout.layout.align().abi == self.tcx().data_layout.pointer_align.abi
+        if let Ok(layout) = tcx.layout_of(obligation.param_env.and(self_ty))
+            && layout.layout.is_pointer_like(&tcx.data_layout)
         {
             candidates.vec.push(BuiltinCandidate { has_nested: false });
         }