1 files changed, 46 insertions, 0 deletions
diff --git a/absl/flags/flag.cc b/absl/flags/flag.cc
new file mode 100644
index 00000000..0858259b
--- /dev/null
+++ b/absl/flags/flag.cc
@@ -0,0 +1,46 @@
+//
+//  Copyright 2019 The Abseil Authors.
+//
+// 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
+//
+//      https://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 "absl/flags/flag.h"
+
+#include <cstring>
+
+namespace absl {
+inline namespace lts_2019_08_08 {
+
+// We want to validate the type mismatch between type definition and
+// declaration. The lock-free implementation does not allow us to do it,
+// so in debug builds we always use the slower implementation, which always
+// validates the type.
+#ifndef NDEBUG
+#define ABSL_FLAGS_ATOMIC_GET(T) \
+  T GetFlag(const absl::Flag<T>& flag) { return flag.Get(); }
+#else
+#define ABSL_FLAGS_ATOMIC_GET(T)         \
+  T GetFlag(const absl::Flag<T>& flag) { \
+    T result;                            \
+    if (flag.AtomicGet(&result)) {       \
+      return result;                     \
+    }                                    \
+    return flag.Get();                   \
+  }
+#endif
+
+ABSL_FLAGS_INTERNAL_FOR_EACH_LOCK_FREE(ABSL_FLAGS_ATOMIC_GET)
+
+#undef ABSL_FLAGS_ATOMIC_GET
+
+}  // inline namespace lts_2019_08_08
+}  // namespace absl