Normalize predicates during method winnowing.

Fixes #20604.
Fixes #20378.

Author: nikomatsakis

src/librustc_typeck/check/method/probe.rs

@@ -807,26 +807,26 @@ impl<'a,'tcx> ProbeContext<'a,'tcx> {
             match probe.kind {
                 InherentImplCandidate(impl_def_id, ref substs) |
                 ExtensionImplCandidate(impl_def_id, _, ref substs, _) => {
+                    let selcx = &mut traits::SelectionContext::new(self.infcx(), self.fcx);
+                    let cause = traits::ObligationCause::misc(self.span, self.fcx.body_id);
+
                     // Check whether the impl imposes obligations we have to worry about.
                     let impl_generics = ty::lookup_item_type(self.tcx(), impl_def_id).generics;
                     let impl_bounds = impl_generics.to_bounds(self.tcx(), substs);
-                    // FIXME(#20378) assoc type normalization here?
-
-                    // Erase any late-bound regions bound in the impl
-                    // which appear in the bounds.
-                    let impl_bounds = self.erase_late_bound_regions(&ty::Binder(impl_bounds));
+                    let traits::Normalized { value: impl_bounds,
+                                             obligations: norm_obligations } =
+                        traits::normalize(selcx, cause.clone(), &impl_bounds);
 
                     // Convert the bounds into obligations.
                     let obligations =
-                        traits::predicates_for_generics(
-                            self.tcx(),
-                            traits::ObligationCause::misc(self.span, self.fcx.body_id),
-                            &impl_bounds);
+                        traits::predicates_for_generics(self.tcx(),
+                                                        cause.clone(),
+                                                        &impl_bounds);
                     debug!("impl_obligations={}", obligations.repr(self.tcx()));
 
                     // Evaluate those obligations to see if they might possibly hold.
-                    let mut selcx = traits::SelectionContext::new(self.infcx(), self.fcx);
-                    obligations.all(|o| selcx.evaluate_obligation(o))
+                    obligations.all(|o| selcx.evaluate_obligation(o)) &&
+                        norm_obligations.iter().all(|o| selcx.evaluate_obligation(o))
                 }
 
                 ObjectCandidate(..) |

src/test/run-pass/method-normalize-bounds-issue-20604.rs

@@ -0,0 +1,65 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Test that we handle projection types which wind up important for
+// resolving methods. This test was reduced from a larger example; the
+// call to `foo()` at the end was failing to resolve because the
+// winnowing stage of method resolution failed to handle an associated
+// type projection.
+
+#![feature(associated_types)]
+
+trait Hasher {
+    type Output;
+    fn finish(&self) -> Self::Output;
+}
+
+trait Hash<H: Hasher> {
+    fn hash(&self, h: &mut H);
+}
+
+trait HashState {
+    type Wut: Hasher;
+    fn hasher(&self) -> Self::Wut;
+}
+
+struct SipHasher;
+impl Hasher for SipHasher {
+    type Output = u64;
+    fn finish(&self) -> u64 { 4 }
+}
+
+impl Hash<SipHasher> for int {
+    fn hash(&self, h: &mut SipHasher) {}
+}
+
+struct SipState;
+impl HashState for SipState {
+    type Wut = SipHasher;
+    fn hasher(&self) -> SipHasher { SipHasher }
+}
+
+struct Map<S> {
+    s: S,
+}
+
+impl<S> Map<S>
+    where S: HashState,
+          <S as HashState>::Wut: Hasher<Output=u64>,
+{
+    fn foo<K>(&self, k: K) where K: Hash< <S as HashState>::Wut> {}
+}
+
+fn foo<K: Hash<SipHasher>>(map: &Map<SipState>) {
+    map.foo(22);
+}
+
+fn main() {}
+