From 2b356118b6af062ba794541076e7ae5e0a3e3c26 Mon Sep 17 00:00:00 2001
From: Tudor Bosman <tudorb@fb.com>
Date: Mon, 26 Aug 2013 21:39:36 -0700
Subject: [PATCH] Expand the range where uninitialized warnings are ignored

Summary: gcc 4.8 is picky

Test Plan: folly tests, compiled unicorn with gcc 4.8

Reviewed By: andrei.alexandrescu@fb.com

FB internal diff: D945336
---
 folly/experimental/Bits.h | 41 +++++++++++++++++++++++++--------------
 1 file changed, 26 insertions(+), 15 deletions(-)

diff --git a/folly/experimental/Bits.h b/folly/experimental/Bits.h
index df23d859..5983988d 100644
--- a/folly/experimental/Bits.h
+++ b/folly/experimental/Bits.h
@@ -52,6 +52,7 @@ struct BitsTraits<Unaligned<T>, typename std::enable_if<
   static T loadRMW(const Unaligned<T>& x) {
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wuninitialized"
+#pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
     return x.value;
 #pragma GCC diagnostic pop
   }
@@ -67,6 +68,7 @@ struct BitsTraits<T, typename std::enable_if<
   static T loadRMW(const T& x) {
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wuninitialized"
+#pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
     return x;
 #pragma GCC diagnostic pop
   }
@@ -164,6 +166,13 @@ struct Bits {
   }
 };
 
+// gcc 4.8 needs more -Wmaybe-uninitialized tickling, as it propagates the
+// taint upstream from loadRMW
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wuninitialized"
+#pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+
 template <class T, class Traits>
 inline void Bits<T, Traits>::set(T* p, size_t bit) {
   T& block = p[blockIndex(bit)];
@@ -176,11 +185,6 @@ inline void Bits<T, Traits>::clear(T* p, size_t bit) {
   Traits::store(block, Traits::loadRMW(block) & ~(one << bitOffset(bit)));
 }
 
-template <class T, class Traits>
-inline bool Bits<T, Traits>::test(const T* p, size_t bit) {
-  return Traits::load(p[blockIndex(bit)]) & (one << bitOffset(bit));
-}
-
 template <class T, class Traits>
 inline void Bits<T, Traits>::set(T* p, size_t bitStart, size_t count,
                                  UnderlyingType value) {
@@ -198,6 +202,23 @@ inline void Bits<T, Traits>::set(T* p, size_t bitStart, size_t count,
   }
 }
 
+template <class T, class Traits>
+inline void Bits<T, Traits>::innerSet(T* p, size_t offset, size_t count,
+                                      UnderlyingType value) {
+  // Mask out bits and set new value
+  UnderlyingType v = Traits::loadRMW(*p);
+  v &= ~(ones(count) << offset);
+  v |= (value << offset);
+  Traits::store(*p, v);
+}
+
+#pragma GCC diagnostic pop
+
+template <class T, class Traits>
+inline bool Bits<T, Traits>::test(const T* p, size_t bit) {
+  return Traits::load(p[blockIndex(bit)]) & (one << bitOffset(bit));
+}
+
 template <class T, class Traits>
 inline auto Bits<T, Traits>::get(const T* p, size_t bitStart, size_t count)
   -> UnderlyingType {
@@ -215,16 +236,6 @@ inline auto Bits<T, Traits>::get(const T* p, size_t bitStart, size_t count)
   }
 }
 
-template <class T, class Traits>
-inline void Bits<T, Traits>::innerSet(T* p, size_t offset, size_t count,
-                                      UnderlyingType value) {
-  // Mask out bits and set new value
-  UnderlyingType v = Traits::loadRMW(*p);
-  v &= ~(ones(count) << offset);
-  v |= (value << offset);
-  Traits::store(*p, v);
-}
-
 template <class T, class Traits>
 inline auto Bits<T, Traits>::innerGet(const T* p, size_t offset, size_t count)
   -> UnderlyingType {
-- 
2.34.1