2 files changed, 26 insertions, 1 deletions
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index e03c5721c6c..6d8c9146541 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -1046,7 +1046,14 @@ bool Sema::FindAllocationFunctions(SourceLocation StartLoc, SourceRange Range,
 
   llvm::SmallVector<std::pair<DeclAccessPair,FunctionDecl*>, 2> Matches;
 
-  if (NumPlaceArgs > 0) {
+  // Whether we're looking for a placement operator delete is dictated
+  // by whether we selected a placement operator new, not by whether
+  // we had explicit placement arguments.  This matters for things like
+  //   struct A { void *operator new(size_t, int = 0); ... };
+  //   A *a = new A()
+  bool isPlacementNew = (NumPlaceArgs > 0 || OperatorNew->param_size() != 1);
+
+  if (isPlacementNew) {
     // C++ [expr.new]p20:
     //   A declaration of a placement deallocation function matches the
     //   declaration of a placement allocation function if it has the
diff --git a/clang/test/SemaCXX/new-delete.cpp b/clang/test/SemaCXX/new-delete.cpp
index ef20aee009c..f6129d19841 100644
--- a/clang/test/SemaCXX/new-delete.cpp
+++ b/clang/test/SemaCXX/new-delete.cpp
@@ -354,3 +354,21 @@ namespace DeleteParam {
     void operator delete(void* const);
   };
 }
+
+// <rdar://problem/8427878>
+// Test that the correct 'operator delete' is selected to pair with
+// the unexpected placement 'operator new'.
+namespace PairedDelete {
+  template <class T> struct A {
+    A();
+    void *operator new(size_t s, double d = 0);
+    void operator delete(void *p, double d);
+    void operator delete(void *p) {
+      T::dealloc(p);
+    }
+  };
+
+  A<int> *test() {
+    return new A<int>();
+  }
+}