Consider obligations when checking for self methods

Author: oli-obk

compiler/rustc_hir_typeck/src/method/probe.rs

@@ -651,8 +651,8 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         }
     }
 
+    #[instrument(level = "debug", skip(self))]
     fn assemble_probe(&mut self, self_ty: &Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>) {
-        debug!("assemble_probe: self_ty={:?}", self_ty);
         let raw_self_ty = self_ty.value.value;
         match *raw_self_ty.kind() {
             ty::Dynamic(data, ..) if let Some(p) = data.principal() => {
@@ -730,13 +730,12 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         }
     }
 
+    #[instrument(level = "debug", skip(self))]
     fn assemble_inherent_impl_probe(&mut self, impl_def_id: DefId) {
         if !self.impl_dups.insert(impl_def_id) {
             return; // already visited
         }
 
-        debug!("assemble_inherent_impl_probe {:?}", impl_def_id);
-
         for item in self.impl_or_trait_item(impl_def_id) {
             if !self.has_applicable_self(&item) {
                 // No receiver declared. Not a candidate.
@@ -786,9 +785,8 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         }
     }
 
+    #[instrument(level = "debug", skip(self))]
     fn assemble_inherent_candidates_from_object(&mut self, self_ty: Ty<'tcx>) {
-        debug!("assemble_inherent_candidates_from_object(self_ty={:?})", self_ty);
-
         let principal = match self_ty.kind() {
             ty::Dynamic(ref data, ..) => Some(data),
             _ => None,
@@ -835,9 +833,9 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         });
     }
 
+    #[instrument(level = "debug", skip(self))]
     fn assemble_inherent_candidates_from_param(&mut self, param_ty: ty::ParamTy) {
         // FIXME: do we want to commit to this behavior for param bounds?
-        debug!("assemble_inherent_candidates_from_param(param_ty={:?})", param_ty);
 
         let bounds = self.param_env.caller_bounds().iter().filter_map(|predicate| {
             let bound_predicate = predicate.kind();
@@ -904,6 +902,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         }
     }
 
+    #[instrument(level = "debug", skip(self))]
     fn assemble_extension_candidates_for_traits_in_scope(&mut self) {
         let mut duplicates = FxHashSet::default();
         let opt_applicable_traits = self.tcx.in_scope_traits(self.scope_expr_id);
@@ -920,6 +919,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         }
     }
 
+    #[instrument(level = "debug", skip(self))]
     fn assemble_extension_candidates_for_all_traits(&mut self) {
         let mut duplicates = FxHashSet::default();
         for trait_info in suggest::all_traits(self.tcx) {
@@ -956,12 +956,12 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         }
     }
 
+    #[instrument(level = "debug", skip(self))]
     fn assemble_extension_candidates_for_trait(
         &mut self,
         import_ids: &SmallVec<[LocalDefId; 1]>,
         trait_def_id: DefId,
     ) {
-        debug!("assemble_extension_candidates_for_trait(trait_def_id={:?})", trait_def_id);
         let trait_args = self.fresh_args_for_item(self.span, trait_def_id);
         let trait_ref = ty::TraitRef::new(self.tcx, trait_def_id, trait_args);
 
@@ -1066,6 +1066,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
     ///////////////////////////////////////////////////////////////////////////
     // THE ACTUAL SEARCH
 
+    #[instrument(level = "debug", skip(self))]
     fn pick(mut self) -> PickResult<'tcx> {
         assert!(self.method_name.is_some());
 
@@ -1492,12 +1493,10 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                 // Thus we need to prevent them from trying to match the `&_` autoref
                 // candidates that get created for `&self` trait methods.
                 ty::Alias(ty::Opaque, alias_ty)
-                    if self.infcx.can_define_opaque_ty(alias_ty.def_id) =>
+                    if self.infcx.can_define_opaque_ty(alias_ty.def_id)
+                        && !probe.xform_self_ty.is_ty_var() =>
                 {
-                    if !probe.xform_self_ty.is_ty_var() {
-                        return ProbeResult::NoMatch;
-                    }
-                    vec![]
+                    return ProbeResult::NoMatch;
                 }
                 _ => match self.at(&ObligationCause::dummy(), self.param_env).sup(
                     DefineOpaqueTypes::Yes,
@@ -1767,6 +1766,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
     /// Similarly to `probe_for_return_type`, this method attempts to find the best matching
     /// candidate method where the method name may have been misspelled. Similarly to other
     /// edit distance based suggestions, we provide at most one such suggestion.
+    #[instrument(level = "debug", skip(self))]
     pub(crate) fn probe_for_similar_candidate(
         &mut self,
     ) -> Result<Option<ty::AssocItem>, MethodError<'tcx>> {

tests/ui/impl-trait/recursive-parent-trait-method-call.rs

@@ -1,4 +1,8 @@
+//! This test checks that we can resolve the `boxed` method call to `FutureExt`,
+//! because we know that the anonymous future does not implement `StreamExt`.
+
 //@ edition: 2021
+//@ check-pass
 
 use std::future::Future;
 use std::pin::Pin;
@@ -22,7 +26,6 @@ fn go(i: usize) -> impl Future<Output = ()> + Send + 'static {
         if i != 0 {
             spawn(async move {
                 let fut = go(i - 1).boxed();
-                //~^ ERROR: multiple applicable items in scope
                 fut.await;
             })
             .await;