Remove const from _Atomic vars to make Clang happy

Clang does not allow using C11's atomic_load on const _Atomic variables.
Previously it just disabled use of C11 atomics if atomic_load didn't work on a
const _Atomic variable, but I think I'd prefer to have Clang use C11 atomics
for the added features (more explicit memory ordering) even if it means a few
instances of breaking const.

2 files changed, 26 insertions, 6 deletions

diff --git a/OpenAL32/Include/alMain.h b/OpenAL32/Include/alMain.h
index b604c547..174210fa 100644
--- a/OpenAL32/Include/alMain.h
+++ b/OpenAL32/Include/alMain.h
@@ -204,6 +204,20 @@ AL_API const ALchar* AL_APIENTRY alGetStringiSOFT(ALenum pname, ALsizei index);
 #endif
 
 
+#ifdef __GNUC__
+/* This helps cast away the const-ness of a pointer without accidentally
+ * changing the pointer type. This is necessary due to Clang's inability to use
+ * atomic_load on a const _Atomic variable.
+ */
+#define CONST_CAST(T, V) __extension__({                                      \
+    const T _tmp = (V);                                                       \
+    (T)_tmp;                                                                  \
+})
+#else
+#define CONST_CAST(T, V) ((T)(V))
+#endif
+
+
 typedef ALint64SOFT ALint64;
 typedef ALuint64SOFT ALuint64;
 
diff --git a/OpenAL32/alSource.c b/OpenAL32/alSource.c
index 23b4fb5a..f2c4908f 100644
--- a/OpenAL32/alSource.c
+++ b/OpenAL32/alSource.c
@@ -1407,7 +1407,8 @@ static ALboolean GetSourceiv(ALsource *Source, ALCcontext *Context, SourceProp p
                 while(BufferList && BufferList != Current)
                 {
                     played++;
-                    BufferList = ATOMIC_LOAD(&BufferList->next, almemory_order_relaxed);
+                    BufferList = ATOMIC_LOAD(&CONST_CAST(ALbufferlistitem*,BufferList)->next,
+                                             almemory_order_relaxed);
                 }
                 *values = played;
             }
@@ -3177,7 +3178,8 @@ static ALint64 GetSourceSampleOffset(ALsource *Source, ALCcontext *context, ALui
         {
             if(BufferList->buffer)
                 readPos += (ALuint64)BufferList->buffer->SampleLen << 32;
-            BufferList = ATOMIC_LOAD(&BufferList->next, almemory_order_relaxed);
+            BufferList = ATOMIC_LOAD(&CONST_CAST(ALbufferlistitem*,BufferList)->next,
+                                     almemory_order_relaxed);
         }
         readPos = minu64(readPos, U64(0x7fffffffffffffff));
     }
@@ -3233,13 +3235,15 @@ static ALdouble GetSourceSecOffset(ALsource *Source, ALCcontext *context, ALuint
                 if(!BufferFmt) BufferFmt = buffer;
                 readPos += (ALuint64)buffer->SampleLen << FRACTIONBITS;
             }
-            BufferList = ATOMIC_LOAD(&BufferList->next, almemory_order_relaxed);
+            BufferList = ATOMIC_LOAD(&CONST_CAST(ALbufferlistitem*,BufferList)->next,
+                                     almemory_order_relaxed);
         }
 
         while(BufferList && !BufferFmt)
         {
             BufferFmt = BufferList->buffer;
-            BufferList = ATOMIC_LOAD(&BufferList->next, almemory_order_relaxed);
+            BufferList = ATOMIC_LOAD(&CONST_CAST(ALbufferlistitem*,BufferList)->next,
+                                     almemory_order_relaxed);
         }
         assert(BufferFmt != NULL);
 
@@ -3302,7 +3306,8 @@ static ALdouble GetSourceOffset(ALsource *Source, ALenum name, ALCcontext *conte
                 totalBufferLen += buffer->SampleLen;
                 if(!readFin) readPos += buffer->SampleLen;
             }
-            BufferList = ATOMIC_LOAD(&BufferList->next, almemory_order_relaxed);
+            BufferList = ATOMIC_LOAD(&CONST_CAST(ALbufferlistitem*,BufferList)->next,
+                                     almemory_order_relaxed);
         }
         assert(BufferFmt != NULL);
 
@@ -3421,7 +3426,8 @@ static ALboolean GetSampleOffset(ALsource *Source, ALuint *offset, ALsizei *frac
     {
         if((BufferFmt=BufferList->buffer) != NULL)
             break;
-        BufferList = ATOMIC_LOAD(&BufferList->next, almemory_order_relaxed);
+        BufferList = ATOMIC_LOAD(&CONST_CAST(ALbufferlistitem*,BufferList)->next,
+                                 almemory_order_relaxed);
     }
     if(!BufferFmt)
     {