Fix the C++11 and GCC-atomic intrinsics when not using GCC

Both Clang and ICC complain about the use of those atomics when used
with a forward-declared pointee. GCC doesn't, which makes me think
it's a GCC bug.

When using QBasicAtomicPointer<Foo> with these atomics, the _q_value
member causes the instantiation of QAtomicOps<Foo>, which causes the
instantiation of the regular member function
QAtomicOps<Foo>::fetchAndAddRelaxed. The problem is that function
takes a QAtomicAdditiveType<Foo>::AdditiveT as parameter, which
requires sizeof(Foo). Clang 3.3 and ICC 14 correctly expand and
complain. GCC 4.7-4.9 apparently don't.

The fix is to apply the same trick we used for the other atomics:
change all ops functions (including fetchAndAddRelaxed) to be member
templates. That way, they can't be expanded until the actual use.

Clang errors:
qgenericatomic.h:73:33: error: invalid application of 'sizeof' to an incomplete type 'QMutexData'
qatomic_gcc.h:136:48: note: in instantiation of template class 'QAtomicAdditiveType<QMutexData *>' requested here
qbasicatomic.h:272:22: note: in instantiation of template class 'QAtomicOps<QMutexData *>' requested here

ICC errors:
qgenericatomic.h(73): error: incomplete type is not allowed
    detected during:
      instantiation of class "QAtomicAdditiveType<T *> [with T=QMutexData]" at line 111 of "qatomic_cxx11.h"
      instantiation of class "QAtomicOps<T> [with T=QMutexData *]" at line 272 of "qbasicatomic.h"

Found-by: Tor Arne
Change-Id: I9b10648cd47109a943b34a4c9926d77cd0c4fe12
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@digia.com>
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>

1 files changed, 42 insertions, 35 deletions

diff --git a/src/corelib/arch/qatomic_cxx11.h b/src/corelib/arch/qatomic_cxx11.h
index 3119edaf45..ed19064724 100644
--- a/src/corelib/arch/qatomic_cxx11.h
+++ b/src/corelib/arch/qatomic_cxx11.h
@@ -105,56 +105,56 @@ template<> struct QAtomicIntegerTraits<char32_t> { enum { IsInteger = 1 }; };
 #define Q_ATOMIC_INT64_FETCH_AND_STORE_IS_ALWAYS_NATIVE
 #define Q_ATOMIC_INT64_FETCH_AND_ADD_IS_ALWAYS_NATIVE
 
-template <typename T> struct QAtomicOps
+template <typename X> struct QAtomicOps
 {
-    typedef std::atomic<T> Type;
-    typedef typename QAtomicAdditiveType<T>::AdditiveT _AdditiveType;
-    static const int AddScale = QAtomicAdditiveType<T>::AddScale;
+    typedef std::atomic<X> Type;
 
-    static inline
-    T load(const Type &_q_value) Q_DECL_NOTHROW
+    template <typename T> static inline
+    T load(const std::atomic<T> &_q_value) Q_DECL_NOTHROW
     {
         return _q_value.load(std::memory_order_relaxed);
     }
 
-    static inline
-    T load(const volatile Type &_q_value) Q_DECL_NOTHROW
+    template <typename T> static inline
+    T load(const volatile std::atomic<T> &_q_value) Q_DECL_NOTHROW
     {
         return _q_value.load(std::memory_order_relaxed);
     }
 
-    static inline
-    T loadAcquire(const Type &_q_value) Q_DECL_NOTHROW
+    template <typename T> static inline
+    T loadAcquire(const std::atomic<T> &_q_value) Q_DECL_NOTHROW
     {
         return _q_value.load(std::memory_order_acquire);
     }
 
-    static inline
-    T loadAcquire(const volatile Type &_q_value) Q_DECL_NOTHROW
+    template <typename T> static inline
+    T loadAcquire(const volatile std::atomic<T> &_q_value) Q_DECL_NOTHROW
     {
         return _q_value.load(std::memory_order_acquire);
     }
 
-    static inline
-    void store(Type &_q_value, T newValue) Q_DECL_NOTHROW
+    template <typename T> static inline
+    void store(std::atomic<T> &_q_value, T newValue) Q_DECL_NOTHROW
     {
         _q_value.store(newValue, std::memory_order_relaxed);
     }
 
-    static inline
-    void storeRelease(Type &_q_value, T newValue) Q_DECL_NOTHROW
+    template <typename T> static inline
+    void storeRelease(std::atomic<T> &_q_value, T newValue) Q_DECL_NOTHROW
     {
         _q_value.store(newValue, std::memory_order_release);
     }
 
     static inline Q_DECL_CONSTEXPR bool isReferenceCountingNative() Q_DECL_NOTHROW { return true; }
     static inline Q_DECL_CONSTEXPR bool isReferenceCountingWaitFree() Q_DECL_NOTHROW { return false; }
-    static inline bool ref(Type &_q_value)
+    template <typename T>
+    static inline bool ref(std::atomic<T> &_q_value)
     {
         return ++_q_value != 0;
     }
 
-    static inline bool deref(Type &_q_value) Q_DECL_NOTHROW
+    template <typename T>
+    static inline bool deref(std::atomic<T> &_q_value) Q_DECL_NOTHROW
     {
         return --_q_value != 0;
     }
@@ -162,22 +162,25 @@ template <typename T> struct QAtomicOps
     static inline Q_DECL_CONSTEXPR bool isTestAndSetNative() Q_DECL_NOTHROW { return false; }
     static inline Q_DECL_CONSTEXPR bool isTestAndSetWaitFree() Q_DECL_NOTHROW { return false; }
 
-    static
+    template <typename T> static
     bool testAndSetRelaxed(Type &_q_value, T expectedValue, T newValue) Q_DECL_NOTHROW
     {
         return _q_value.compare_exchange_strong(expectedValue, newValue, std::memory_order_relaxed);
     }
 
+    template <typename T>
     static bool testAndSetAcquire(Type &_q_value, T expectedValue, T newValue) Q_DECL_NOTHROW
     {
         return _q_value.compare_exchange_strong(expectedValue, newValue, std::memory_order_acquire);
     }
 
+    template <typename T>
     static bool testAndSetRelease(Type &_q_value, T expectedValue, T newValue) Q_DECL_NOTHROW
     {
         return _q_value.compare_exchange_strong(expectedValue, newValue, std::memory_order_release);
     }
 
+    template <typename T>
     static bool testAndSetOrdered(Type &_q_value, T expectedValue, T newValue) Q_DECL_NOTHROW
     {
         return _q_value.compare_exchange_strong(expectedValue, newValue, std::memory_order_acq_rel);
@@ -186,22 +189,26 @@ template <typename T> struct QAtomicOps
     static inline Q_DECL_CONSTEXPR bool isFetchAndStoreNative() Q_DECL_NOTHROW { return false; }
     static inline Q_DECL_CONSTEXPR bool isFetchAndStoreWaitFree() Q_DECL_NOTHROW { return false; }
 
-    static T fetchAndStoreRelaxed(Type &_q_value, T newValue) Q_DECL_NOTHROW
+    template <typename T>
+    static T fetchAndStoreRelaxed(std::atomic<T> &_q_value, T newValue) Q_DECL_NOTHROW
     {
         return _q_value.exchange(newValue, std::memory_order_relaxed);
     }
 
-    static T fetchAndStoreAcquire(Type &_q_value, T newValue) Q_DECL_NOTHROW
+    template <typename T>
+    static T fetchAndStoreAcquire(std::atomic<T> &_q_value, T newValue) Q_DECL_NOTHROW
     {
         return _q_value.exchange(newValue, std::memory_order_acquire);
     }
 
-    static T fetchAndStoreRelease(Type &_q_value, T newValue) Q_DECL_NOTHROW
+    template <typename T>
+    static T fetchAndStoreRelease(std::atomic<T> &_q_value, T newValue) Q_DECL_NOTHROW
     {
         return _q_value.exchange(newValue, std::memory_order_release);
     }
 
-    static T fetchAndStoreOrdered(Type &_q_value, T newValue) Q_DECL_NOTHROW
+    template <typename T>
+    static T fetchAndStoreOrdered(std::atomic<T> &_q_value, T newValue) Q_DECL_NOTHROW
     {
         return _q_value.exchange(newValue, std::memory_order_acq_rel);
     }
@@ -209,31 +216,31 @@ template <typename T> struct QAtomicOps
     static inline Q_DECL_CONSTEXPR bool isFetchAndAddNative() Q_DECL_NOTHROW { return false; }
     static inline Q_DECL_CONSTEXPR bool isFetchAndAddWaitFree() Q_DECL_NOTHROW { return false; }
 
-    static
-    T fetchAndAddRelaxed(Type &_q_value, _AdditiveType valueToAdd) Q_DECL_NOTHROW
+    template <typename T> static inline
+    T fetchAndAddRelaxed(std::atomic<T> &_q_value, typename QAtomicAdditiveType<T>::AdditiveT valueToAdd) Q_DECL_NOTHROW
     {
-        return _q_value.fetch_add(valueToAdd * AddScale,
+        return _q_value.fetch_add(valueToAdd * QAtomicAdditiveType<T>::AddScale,
                                   std::memory_order_relaxed);
     }
 
-    static
-    T fetchAndAddAcquire(Type &_q_value, _AdditiveType valueToAdd) Q_DECL_NOTHROW
+    template <typename T> static inline
+    T fetchAndAddAcquire(std::atomic<T> &_q_value, typename QAtomicAdditiveType<T>::AdditiveT valueToAdd) Q_DECL_NOTHROW
     {
-        return _q_value.fetch_add(valueToAdd * AddScale,
+        return _q_value.fetch_add(valueToAdd * QAtomicAdditiveType<T>::AddScale,
                                   std::memory_order_acquire);
     }
 
-    static
-    T fetchAndAddRelease(Type &_q_value, _AdditiveType valueToAdd) Q_DECL_NOTHROW
+    template <typename T> static inline
+    T fetchAndAddRelease(std::atomic<T> &_q_value, typename QAtomicAdditiveType<T>::AdditiveT valueToAdd) Q_DECL_NOTHROW
     {
-        return _q_value.fetch_add(valueToAdd * AddScale,
+        return _q_value.fetch_add(valueToAdd * QAtomicAdditiveType<T>::AddScale,
                                   std::memory_order_release);
     }
 
-    static
-    T fetchAndAddOrdered(Type &_q_value, _AdditiveType valueToAdd) Q_DECL_NOTHROW
+    template <typename T> static inline
+    T fetchAndAddOrdered(std::atomic<T> &_q_value, typename QAtomicAdditiveType<T>::AdditiveT valueToAdd) Q_DECL_NOTHROW
     {
-        return _q_value.fetch_add(valueToAdd * AddScale,
+        return _q_value.fetch_add(valueToAdd * QAtomicAdditiveType<T>::AddScale,
                                   std::memory_order_acq_rel);
     }
 };