Merge pull request #6680 from apple/revert-6679-archetype-anchor-cleanup

Author: swift-ci

lib/AST/ArchetypeBuilder.cpp

@@ -374,22 +374,13 @@ bool ArchetypeBuilder::PotentialArchetype::isBetterArchetypeAnchor(
 auto ArchetypeBuilder::PotentialArchetype::getArchetypeAnchor()
        -> PotentialArchetype * {
 
-  // Find the best archetype within this equivalence class.
-  PotentialArchetype *rep = getRepresentative();
-  auto best = rep;
-  for (auto pa : rep->getEquivalenceClass()) {
+  // Default to the representative, unless we find something better.
+  PotentialArchetype *best = getRepresentative();
+  for (auto pa : best->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;
 }
 
@@ -1058,10 +1049,18 @@ static int compareDependentTypes(ArchetypeBuilder::PotentialArchetype * const* p
       if (int compareProtocols
             = ProtocolType::compareProtocols(&protoa, &protob))
         return compareProtocols;
-    } else {
-      // A resolved archetype is always ordered before an unresolved one.
-      return -1;
+
+      // - 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;
     }
+
+    // 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 : P1 [protocol
 // 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 [protocol
 // CHECK-GENERIC-NEXT:   T[.P2].AssocP2[.P1].Assoc == T[.P2].AssocP2[.P1].Assoc [redundant
+// CHECK-GENERIC-NEXT:   T[.P2].AssocP2[.P1].Assoc : P3 [explicit
 // CHECK-GENERIC-NEXT: Generic signature
 
 // <rdar://problem/19620340>