Autoderef privacy for methods

src/librustc_typeck/check/method/mod.rs

@@ -43,6 +43,9 @@ pub enum MethodError<'tcx> {
 
     // Using a `Fn`/`FnMut`/etc method on a raw closure type before we have inferred its kind.
     ClosureAmbiguity(/* DefId of fn trait */ DefId),
+
+    // Found an applicable method, but it is not visible.
+    PrivateMatch(Def),
 }
 
 // Contains a list of static methods that may apply, a list of unsatisfied trait predicates which
@@ -90,6 +93,7 @@ pub fn exists<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
         Err(NoMatch(..)) => false,
         Err(Ambiguity(..)) => true,
         Err(ClosureAmbiguity(..)) => true,
+        Err(PrivateMatch(..)) => true,
     }
 }
 

src/librustc_typeck/check/method/probe.rs

@@ -16,6 +16,7 @@ use super::suggest;
 use check;
 use check::{FnCtxt, UnresolvedTypeAction};
 use middle::def_id::DefId;
+use middle::def::Def;
 use rustc::ty::subst;
 use rustc::ty::subst::Subst;
 use rustc::traits;
@@ -47,6 +48,9 @@ struct ProbeContext<'a, 'tcx:'a> {
     /// used for error reporting
     static_candidates: Vec<CandidateSource>,
 
+    /// Some(candidate) if there is a private candidate
+    private_candidate: Option<Def>,
+
     /// Collects near misses when trait bounds for type parameters are unsatisfied and is only used
     /// for error reporting
     unsatisfied_predicates: Vec<TraitRef<'tcx>>
@@ -247,6 +251,7 @@ impl<'a,'tcx> ProbeContext<'a,'tcx> {
             steps: Rc::new(steps),
             opt_simplified_steps: opt_simplified_steps,
             static_candidates: Vec::new(),
+            private_candidate: None,
             unsatisfied_predicates: Vec::new(),
         }
     }
@@ -256,6 +261,7 @@ impl<'a,'tcx> ProbeContext<'a,'tcx> {
         self.extension_candidates.clear();
         self.impl_dups.clear();
         self.static_candidates.clear();
+        self.private_candidate = None;
     }
 
     fn tcx(&self) -> &'a TyCtxt<'tcx> {
@@ -407,6 +413,11 @@ impl<'a,'tcx> ProbeContext<'a,'tcx> {
             return self.record_static_candidate(ImplSource(impl_def_id));
         }
 
+        if item.vis() != hir::Public && !self.fcx.private_item_is_visible(item.def_id()) {
+            self.private_candidate = Some(item.def());
+            return
+        }
+
         let (impl_ty, impl_substs) = self.impl_ty_and_substs(impl_def_id);
         let impl_ty = impl_ty.subst(self.tcx(), &impl_substs);
 
@@ -846,6 +857,7 @@ impl<'a,'tcx> ProbeContext<'a,'tcx> {
         }
 
         let static_candidates = mem::replace(&mut self.static_candidates, vec![]);
+        let private_candidate = mem::replace(&mut self.private_candidate, None);
         let unsatisfied_predicates = mem::replace(&mut self.unsatisfied_predicates, vec![]);
 
         // things failed, so lets look at all traits, for diagnostic purposes now:
@@ -879,9 +891,13 @@ impl<'a,'tcx> ProbeContext<'a,'tcx> {
                 // this error only occurs when assembling candidates
                 tcx.sess.span_bug(span, "encountered ClosureAmbiguity from pick_core");
             }
-            None => vec![],
+            _ => vec![],
         };
 
+        if let Some(def) = private_candidate {
+            return Err(MethodError::PrivateMatch(def));
+        }
+
         Err(MethodError::NoMatch(NoMatchData::new(static_candidates, unsatisfied_predicates,
                                                   out_of_scope_traits, self.mode)))
     }

src/librustc_typeck/check/method/suggest.rs

@@ -91,7 +91,7 @@ pub fn report_error<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
         MethodError::NoMatch(NoMatchData { static_candidates: static_sources,
                                            unsatisfied_predicates,
                                            out_of_scope_traits,
-                                           mode }) => {
+                                           mode, .. }) => {
             let cx = fcx.tcx();
 
             let mut err = fcx.type_error_struct(
@@ -208,6 +208,11 @@ pub fn report_error<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
             };
             fcx.sess().span_err(span, &msg);
         }
+
+        MethodError::PrivateMatch(def) => {
+            let msg = format!("{} `{}` is private", def.kind_name(), item_name);
+            fcx.tcx().sess.span_err(span, &msg);
+        }
     }
 
     fn report_candidates(fcx: &FnCtxt,

src/librustc_typeck/check/mod.rs

@@ -3757,23 +3757,30 @@ pub fn resolve_ty_and_def_ufcs<'a, 'b, 'tcx>(fcx: &FnCtxt<'b, 'tcx>,
                                                      &ty_segments[base_ty_end..]);
         let item_segment = path.segments.last().unwrap();
         let item_name = item_segment.identifier.name;
-        match method::resolve_ufcs(fcx, span, item_name, ty, node_id) {
-            Ok(def) => {
-                // Write back the new resolution.
-                fcx.ccx.tcx.def_map.borrow_mut()
-                       .insert(node_id, def::PathResolution {
-                   base_def: def,
-                   depth: 0
-                });
-                Some((Some(ty), slice::ref_slice(item_segment), def))
-            }
+        let def = match method::resolve_ufcs(fcx, span, item_name, ty, node_id) {
+            Ok(def) => Some(def),
             Err(error) => {
+                let def = match error {
+                    method::MethodError::PrivateMatch(def) => Some(def),
+                    _ => None,
+                };
                 if item_name != special_idents::invalid.name {
                     method::report_error(fcx, span, ty, item_name, None, error);
                 }
-                fcx.write_error(node_id);
-                None
+                def
             }
+        };
+
+        if let Some(def) = def {
+            // Write back the new resolution.
+            fcx.ccx.tcx.def_map.borrow_mut().insert(node_id, def::PathResolution {
+                base_def: def,
+                depth: 0,
+            });
+            Some((Some(ty), slice::ref_slice(item_segment), def))
+        } else {
+            fcx.write_error(node_id);
+            None
         }
     }
 }