blanket impls uwu

Author: lcnr

compiler/rustc_hir_typeck/src/writeback.rs

@@ -953,8 +953,10 @@ impl<'cx, 'tcx> TypeFolder<TyCtxt<'tcx>> for Resolver<'cx, 'tcx> {
     }
 
     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
-        debug_assert!(!r.is_bound(), "Should not be resolving bound region.");
-        self.fcx.tcx.lifetimes.re_erased
+        match r.kind() {
+            ty::ReBound(..) => r,
+            _ => self.fcx.tcx.lifetimes.re_erased,
+        }
     }
 
     fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {

compiler/rustc_middle/src/ty/context.rs

@@ -589,7 +589,11 @@ impl<'tcx> Interner for TyCtxt<'tcx> {
             | ty::Bound(_, _) => bug!("unexpected self type: {self_ty}"),
         }
 
-        let trait_impls = tcx.trait_impls_of(trait_def_id);
+        #[allow(rustc::usage_of_type_ir_traits)]
+        self.for_each_blanket_impl(trait_def_id, f)
+    }
+    fn for_each_blanket_impl(self, trait_def_id: DefId, mut f: impl FnMut(DefId)) {
+        let trait_impls = self.trait_impls_of(trait_def_id);
         for &impl_def_id in trait_impls.blanket_impls() {
             f(impl_def_id);
         }

compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs

@@ -886,6 +886,26 @@ where
         };
 
         let mut candidates = vec![];
+
+        let cx = self.cx();
+        cx.for_each_blanket_impl(goal.predicate.trait_def_id(cx), |impl_def_id| {
+            // For every `default impl`, there's always a non-default `impl`
+            // that will *also* apply. There's no reason to register a candidate
+            // for this impl, since it is *not* proof that the trait goal holds.
+            if cx.impl_is_default(impl_def_id) {
+                return;
+            }
+
+            match G::consider_impl_candidate(self, goal, impl_def_id) {
+                Ok(mut candidate) => {
+                    candidate.result.value.certainty =
+                        candidate.result.value.certainty.unify_with(Certainty::AMBIGUOUS);
+                    candidates.push(candidate);
+                }
+                Err(NoSolution) => (),
+            }
+        });
+
         for item_bound in
             self.cx().item_self_bounds(alias_ty.def_id).iter_instantiated(self.cx(), alias_ty.args)
         {

compiler/rustc_type_ir/src/interner.rs

@@ -290,6 +290,7 @@ pub trait Interner:
         self_ty: Self::Ty,
         f: impl FnMut(Self::DefId),
     );
+    fn for_each_blanket_impl(self, trait_def_id: Self::DefId, f: impl FnMut(Self::DefId));
 
     fn has_item_definition(self, def_id: Self::DefId) -> bool;