Merge pull request #6679 from DougGregor/archetype-anchor-cleanup

Author: swift-ci

lib/AST/ArchetypeBuilder.cpp

@@ -374,13 +374,22 @@ bool ArchetypeBuilder::PotentialArchetype::isBetterArchetypeAnchor(
 auto ArchetypeBuilder::PotentialArchetype::getArchetypeAnchor()
        -> PotentialArchetype * {
 
-  // Default to the representative, unless we find something better.
-  PotentialArchetype *best = getRepresentative();
-  for (auto pa : best->getEquivalenceClass()) {
+  // Find the best archetype within this equivalence class.
+  PotentialArchetype *rep = getRepresentative();
+  auto best = rep;
+  for (auto pa : rep->getEquivalenceClass()) {
     if (pa->isBetterArchetypeAnchor(best))
       best = pa;
   }
 
+#ifndef NDEBUG
+  // Make sure that we did, in fact, get one that is better than all others.
+  for (auto pa : rep->getEquivalenceClass()) {
+    assert(!pa->isBetterArchetypeAnchor(best) &&
+           "archetype anchor isn't a total order");
+  }
+#endif
+
   return best;
 }
 
@@ -1049,18 +1058,10 @@ static int compareDependentTypes(ArchetypeBuilder::PotentialArchetype * const* p
       if (int compareProtocols
             = ProtocolType::compareProtocols(&protoa, &protob))
         return compareProtocols;
-
-      // - if one is the representative, put it first.
-      if ((a->getRepresentative() == a) !=
-          (b->getRepresentative() == b))
-        return a->getRepresentative() ? -1 : 1;
-
-      // FIXME: Would be nice if this was a total order.
-      return 0;
+    } else {
+      // A resolved archetype is always ordered before an unresolved one.
+      return -1;
     }
-
-    // A resolved archetype is always ordered before an unresolved one.
-    return -1;
   }
 
   // A resolved archetype is always ordered before an unresolved one.

test/Generics/associated_type_typo.swift

@@ -39,10 +39,10 @@ func typoAssoc4<T : P2>(_: T) where T.Assocp2.assoc : P3 {}
 // CHECK-GENERIC-LABEL: .typoAssoc4@
 // CHECK-GENERIC-NEXT: Requirements:
 // CHECK-GENERIC-NEXT:   T : P2 [explicit
-// CHECK-GENERIC-NEXT:   T[.P2].AssocP2 == T[.P2].AssocP2 [redundant]
 // CHECK-GENERIC-NEXT:   T[.P2].AssocP2 : P1 [protocol
-// CHECK-GENERIC-NEXT:   T[.P2].AssocP2[.P1].Assoc == T[.P2].AssocP2[.P1].Assoc [redundant
+// CHECK-GENERIC-NEXT:   T[.P2].AssocP2 == T[.P2].AssocP2 [redundant]
 // CHECK-GENERIC-NEXT:   T[.P2].AssocP2[.P1].Assoc : P3 [explicit
+// CHECK-GENERIC-NEXT:   T[.P2].AssocP2[.P1].Assoc == T[.P2].AssocP2[.P1].Assoc [redundant
 // CHECK-GENERIC-NEXT: Generic signature
 
 // <rdar://problem/19620340>