Check for the C99 restrict keyword

GCC does not default to C99 mode yet, so does not know restrict, however it
still allows using __restrict in its place

CMakeLists.txt

@@ -66,6 +66,12 @@ CHECK_TYPE_SIZE("unsigned int" SIZEOF_UINT)
 CHECK_TYPE_SIZE("void*" SIZEOF_VOIDP)
 
 
+CHECK_C_SOURCE_COMPILES("int *restrict foo;
+                         int main() {return 0;}" HAVE_RESTRICT)
+CHECK_C_SOURCE_COMPILES("int *__restrict foo;
+                         int main() {return 0;}" HAVE___RESTRICT)
+
+
 # Add definitions, compiler switches, etc.
 INCLUDE_DIRECTORIES(OpenAL32/Include include "${OpenAL_BINARY_DIR}")
 

OpenAL32/Include/alMain.h

@@ -171,6 +171,14 @@ typedef unsigned long long ALuint64;
 #define PRINTF_STYLE(x, y)
 #endif
 
+#if defined(HAVE_RESTRICT)
+#define RESTRICT restrict
+#elif defined(HAVE___RESTRICT)
+#define RESTRICT __restrict
+#else
+#define RESTRICT
+#endif
+
 #ifdef _WIN32
 
 #ifndef _WIN32_WINNT

config.h.in

@@ -97,4 +97,10 @@
 /* Define if we have pthread_setschedparam() */
 #cmakedefine HAVE_PTHREAD_SETSCHEDPARAM
 
+/* Define if we have the restrict keyword */
+#cmakedefine HAVE_RESTRICT
+
+/* Define if we have the __restrict keyword */
+#cmakedefine HAVE___RESTRICT
+
 #endif