Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -2993,7 +2993,7 @@
             << New << getSpecialMember(OldMethod);
           return true;
         }
-      } else if (OldMethod->isExplicitlyDefaulted() && !isFriend) {
+      } else if (OldMethod->getFirstDecl()->isExplicitlyDefaulted() && !isFriend) {
         Diag(NewMethod->getLocation(),
              diag::err_definition_of_explicitly_defaulted_member)
           << getSpecialMember(OldMethod);
Index: test/SemaCXX/cxx0x-defaulted-functions.cpp
===================================================================
--- test/SemaCXX/cxx0x-defaulted-functions.cpp
+++ test/SemaCXX/cxx0x-defaulted-functions.cpp
@@ -150,6 +150,14 @@
   Y::~Y() = default; // expected-error {{definition of explicitly defaulted}}
 }
 
+namespace PR27699 {
+  struct X {
+    X();
+  };
+  X::X() = default; // expected-note {{here}}
+  X::X() = default; // expected-error {{redefinition of 'X'}}
+}
+
 namespace PR14577 {
   template<typename T>
   struct Outer {