From 378a3bbc7ec5298f92f8c43083c2b0f7836348a6 Mon Sep 17 00:00:00 2001
From: Marcelo Juchem <marcelo@fb.com>
Date: Thu, 24 Jan 2013 20:49:47 -0800
Subject: [PATCH] A few fixes for clang support

Summary: fixes for clang support

Test Plan:
rm -rf ~/fbcode/_build/* && fbconfig --clang folly/test && fbmake
rm -rf ~/fbcode/_build/* && fbconfig folly/test && fbmake
_bin/folly/test/format_test
_bin/folly/test/optional_test
_bin/folly/test/has_member_fn_traits_test

Reviewed By: tudorb@fb.com

FB internal diff: D688295
---
 folly/Format-inl.h                   |  2 +-
 folly/Format.h                       |  3 ++-
 folly/Optional.h                     | 12 +++++++-----
 folly/Traits.h                       | 25 +++++++++++++++++++++++++
 folly/test/HasMemberFnTraitsTest.cpp | 10 ++++++----
 5 files changed, 41 insertions(+), 11 deletions(-)

diff --git a/folly/Format-inl.h b/folly/Format-inl.h
index bba7be85..831d3c82 100644
--- a/folly/Format-inl.h
+++ b/folly/Format-inl.h
@@ -377,7 +377,7 @@ class FormatValue<
     UT uval;
     char sign;
     if (std::is_signed<T>::value) {
-      if (val_ < 0) {
+      if (folly::is_negative(val_)) {
         uval = static_cast<UT>(-val_);
         sign = '-';
       } else {
diff --git a/folly/Format.h b/folly/Format.h
index 9571a9a4..628a2a29 100644
--- a/folly/Format.h
+++ b/folly/Format.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2012 Facebook, Inc.
+ * Copyright 2013 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -30,6 +30,7 @@
 #include "folly/FBVector.h"
 #include "folly/Conv.h"
 #include "folly/Range.h"
+#include "folly/Traits.h"
 #include "folly/Likely.h"
 #include "folly/String.h"
 #include "folly/small_vector.h"
diff --git a/folly/Optional.h b/folly/Optional.h
index 506bbb89..5b574f5b 100644
--- a/folly/Optional.h
+++ b/folly/Optional.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2012 Facebook, Inc.
+ * Copyright 2013 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -73,10 +73,12 @@ const None none = nullptr;
  * gcc-4.7 warns about use of uninitialized memory around the use of storage_
  * even though this is explicitly initialized at each point.
  */
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wuninitialized"
-#pragma GCC diagnostic ignored "-Wpragmas"
-#pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+#ifdef __GNUC__
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wuninitialized"
+# pragma GCC diagnostic ignored "-Wpragmas"
+# pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+#endif // __GNUC__
 
 template<class Value>
 class Optional : boost::totally_ordered<Optional<Value>,
diff --git a/folly/Traits.h b/folly/Traits.h
index d2fad50e..d3002dce 100644
--- a/folly/Traits.h
+++ b/folly/Traits.h
@@ -277,6 +277,31 @@ struct IsOneOf<T, T1, Ts...> {
   enum { value = std::is_same<T, T1>::value || IsOneOf<T, Ts...>::value };
 };
 
+/*
+ * Complementary type traits to check for a negative value.
+ *
+ * if(x < 0) yields an error in clang for unsigned types when -Werror is used
+ */
+
+namespace detail {
+
+template <typename T, bool>
+struct is_negative_impl {
+  constexpr static bool check(T x) { return x < 0; }
+};
+
+template <typename T>
+struct is_negative_impl<T, false> {
+  constexpr static bool check(T x) { return false; }
+};
+
+} // namespace detail {
+
+template <typename T>
+constexpr bool is_negative(T x) {
+  return folly::detail::is_negative_impl<T, std::is_signed<T>::value>::check(x);
+}
+
 } // namespace folly
 
 FOLLY_ASSUME_FBVECTOR_COMPATIBLE_3(std::basic_string);
diff --git a/folly/test/HasMemberFnTraitsTest.cpp b/folly/test/HasMemberFnTraitsTest.cpp
index 50efce83..470eb599 100644
--- a/folly/test/HasMemberFnTraitsTest.cpp
+++ b/folly/test/HasMemberFnTraitsTest.cpp
@@ -65,10 +65,12 @@ struct CV {
   void test() const volatile;
 };
 
-#define LOG_VALUE(x) []() { \
-  LOG(INFO) << #x << ": " << boolalpha << (x); \
-  return x; \
-}()
+bool log_value(const char* what, bool result) {
+  LOG(INFO) << what << ": " << boolalpha << result;
+  return result;
+}
+
+#define LOG_VALUE(x) log_value(#x, x)
 
 TEST(HasMemberFnTraits, DirectMembers) {
   EXPECT_TRUE(LOG_VALUE((has_test<Foo, int()>::value)));
-- 
2.34.1