folly/test/SingletonTestStructs: move inlined function to impl file

Reviewed By: yfeldblum

Differential Revision: D4162763

fbshipit-source-id: 25c9bfae2e7679f4b98a3d64ee9f2319eb6e7f4a

folly/test/SingletonTestStructs.cpp

+/*
+ * Copyright 2016 Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <folly/test/SingletonTestStructs.h>
+
+namespace {
+// A simple class that tracks how often instances of the class and
+// subclasses are created, and the ordering.  Also tracks a global
+// unique counter for each object.
+std::atomic<size_t> global_counter(19770326);
+}
+
+std::vector<Watchdog*>& Watchdog::creation_order() {
+  static std::vector<Watchdog*> ret;
+  return ret;
+}
+
+Watchdog::Watchdog() : serial_number(++global_counter) {
+  creation_order().push_back(this);
+}

folly/test/SingletonTestStructs.h

@@ -23,20 +23,10 @@
 
 #include <folly/portability/GTest.h>
 
-// A simple class that tracks how often instances of the class and
-// subclasses are created, and the ordering.  Also tracks a global
-// unique counter for each object.
-std::atomic<size_t> global_counter(19770326);
-
 struct Watchdog {
-  static std::vector<Watchdog*>& creation_order() {
-    static std::vector<Watchdog*> ret;
-    return ret;
-  }
+  static std::vector<Watchdog*>& creation_order();
 
-  Watchdog() : serial_number(++global_counter) {
-    creation_order().push_back(this);
-  }
+  Watchdog();
 
   ~Watchdog() {
     if (creation_order().back() != this) {