---

yaml
---
r: 326585
b: refs/heads/tensorflow
c: f19016b
h: refs/heads/master
i:
  326583: 623179c

Author: DougGregor

[refs]

@@ -816,7 +816,7 @@ refs/tags/swift-DEVELOPMENT-SNAPSHOT-2018-04-25-a: 22f738a831d43aff2b9c9773bcb65
 refs/tags/swift-DEVELOPMENT-SNAPSHOT-2018-05-08-a: 7d98cc16689baba5c8a3b90a9329bdcc1a12b4e9
 refs/heads/cherr42: a566ad54b073c2c56ac0a705d0a5bed9743135a5
 "refs/heads/codable_test_comment_fix": fc8f6824f7f347e1e8db55bff62db385c5728b5a
-refs/heads/tensorflow: 0b7ef3445eeda7fbe29c0edc91aebc1a846a7755
+refs/heads/tensorflow: f19016b94b0f0b8ed2fff8c0d3316504402bc21c
 refs/tags/swift-4.1-DEVELOPMENT-SNAPSHOT-2018-05-11-a: 8126fd7a652e2f70ad6d76505239e34fb2ef3e1a
 refs/tags/swift-4.1-DEVELOPMENT-SNAPSHOT-2018-05-12-a: b3fd3dd84df6717f2e2e9df58c6d7e99fed57086
 refs/tags/swift-4.1-DEVELOPMENT-SNAPSHOT-2018-05-13-a: 71135119579039dc321c5f65d870050fe36efda2

branches/tensorflow/lib/Sema/ConstraintGraph.cpp

@@ -814,19 +814,29 @@ namespace {
     }
 
     /// Perform a depth-first search to produce a from the given type variable,
-    /// notifying the function object \c postVisit after each reachable
-    /// type variable has been visited.
+    /// notifying the function object.
+    ///
+    /// \param getAdjacencies Called to retrieve the set of type variables
+    /// that are adjacent to the given type variable.
+    ///
+    /// \param preVisit Called before visiting the adjacencies of the given
+    /// type variable. When it returns \c true, the adjacencies of this type
+    /// variable will be visited. When \c false, the adjacencies will not be
+    /// visited and \c postVisit will not be called.
+    ///
+    /// \param postVisit Called after visiting the adjacencies of the given
+    /// type variable.
     static void postorderDepthFirstSearchRec(
         TypeVariableType *typeVar,
         llvm::function_ref<
           ArrayRef<TypeVariableType *>(TypeVariableType *)> getAdjacencies,
-        llvm::function_ref<void(TypeVariableType *)> postVisit,
-        SmallPtrSet<TypeVariableType *, 4> &visited) {
-      if (!visited.insert(typeVar).second)
+        llvm::function_ref<bool(TypeVariableType *)> preVisit,
+        llvm::function_ref<void(TypeVariableType *)> postVisit) {
+      if (!preVisit(typeVar))
         return;
 
       for (auto adj : getAdjacencies(typeVar)) {
-        postorderDepthFirstSearchRec(adj, getAdjacencies, postVisit, visited);
+        postorderDepthFirstSearchRec(adj, getAdjacencies, preVisit, postVisit);
       }
 
       postVisit(typeVar);
@@ -855,14 +865,16 @@ namespace {
 
               return oneWayComponent->second.inAdjacencies;
             },
+            [&](TypeVariableType *typeVar) {
+              return visited.insert(typeVar).second;
+            },
             [&](TypeVariableType *dependsOn) {
               // Don't record dependency on ourselves.
               if (dependsOn == inAdj)
                 return;
 
               indirectlyReachable.insert(dependsOn);
-            },
-            visited);
+            });
 
         // Remove any in-adjacency of this component that is indirectly
         // reachable.
@@ -922,13 +934,15 @@ namespace {
 
               return oneWayComponent->second.outAdjacencies;
             },
+            [&](TypeVariableType *typeVar) {
+              return visited.insert(typeVar).second;
+            },
             [&](TypeVariableType *typeVar) {
               // Record this type variable, if it's one of the representative
               // type variables.
               if (validComponents.count(typeVar) > 0)
                 orderedReps.push_back(typeVar);
-            },
-            visited);
+            });
       }
 
       assert(orderedReps.size() == representativeTypeVars.size());