shut up signedness warnings in atomic ops in gcc

unittest/mysys/my_atomic-t.c:
  try both signed and unsigned arguments for atomic ops

include/my_atomic.h

@@ -67,11 +67,56 @@
   v=tmp;
 #endif
 
+#ifdef __GNUC__
+/*
+  we want to be able to use my_atomic_xxx functions with
+  both signed and unsigned integers. But gcc will issue a warning
+  "passing arg N of `my_atomic_XXX' as [un]signed due to prototype"
+  if the signedness of the argument doesn't match the prototype, or
+  "pointer targets in passing argument N of my_atomic_XXX differ in signedness"
+  if int* is used where uint* is expected (or vice versa).
+  Let's shut these warnings up
+*/
+#define make_transparent_unions(S)                              \
+        typedef union {                                         \
+          int  ## S  i;                                         \
+          uint ## S  u;                                         \
+        } U_ ## S   __attribute__ ((transparent_union));        \
+        typedef union {                                         \
+          int  ## S volatile *i;                                \
+          uint ## S volatile *u;                                \
+        } Uv_ ## S   __attribute__ ((transparent_union));
+#define uintptr intptr
+make_transparent_unions(8)
+make_transparent_unions(16)
+make_transparent_unions(32)
+make_transparent_unions(ptr)
+#undef uintptr
+#undef make_transparent_unions
+#define a       U_a.i
+#define cmp     U_cmp.i
+#define v       U_v.i
+#define set     U_set.i
+#else
+#define U_8    int8
+#define U_16   int16
+#define U_32   int32
+#define U_ptr  intptr
+#define Uv_8   int8
+#define Uv_16  int16
+#define Uv_32  int32
+#define Uv_ptr intptr
+#define U_a    volatile *a
+#define U_cmp  *cmp
+#define U_v    v
+#define U_set  set
+#endif /* __GCC__ transparent_union magic */
+
 #ifdef HAVE_INLINE
 
 #define make_atomic_add(S)                                      \
 STATIC_INLINE int ## S my_atomic_add ## S(                      \
-                        int ## S volatile *a, int ## S v)	\
+                        Uv_ ## S U_a, U_ ## S U_v)              \
 {                                                               \
   make_atomic_add_body(S);                                      \
   return v;                                                     \
@@ -79,15 +124,15 @@ STATIC_INLINE int ## S my_atomic_add ## S(			\
 
 #define make_atomic_fas(S)                                      \
 STATIC_INLINE int ## S my_atomic_fas ## S(                      \
-                         int ## S volatile *a, int ## S v)	\
+                         Uv_ ## S U_a, U_ ## S U_v)             \
 {                                                               \
   make_atomic_fas_body(S);                                      \
   return v;                                                     \
 }
 
 #define make_atomic_cas(S)                                      \
-STATIC_INLINE int my_atomic_cas ## S(int ## S volatile *a,	\
-                            int ## S *cmp, int ## S set)	\
+STATIC_INLINE int my_atomic_cas ## S(Uv_ ## S U_a,              \
+                            Uv_ ## S U_cmp, U_ ## S U_set)      \
 {                                                               \
   int8 ret;                                                     \
   make_atomic_cas_body(S);                                      \
@@ -95,7 +140,7 @@ STATIC_INLINE int my_atomic_cas ## S(int ## S volatile *a,	\
 }
 
 #define make_atomic_load(S)                                     \
-STATIC_INLINE int ## S my_atomic_load ## S(int ## S volatile *a) \
+STATIC_INLINE int ## S my_atomic_load ## S(Uv_ ## S U_a)        \
 {                                                               \
   int ## S ret;                                                 \
   make_atomic_load_body(S);                                     \
@@ -104,7 +149,7 @@ STATIC_INLINE int ## S my_atomic_load ## S(int ## S volatile *a) \
 
 #define make_atomic_store(S)                                    \
 STATIC_INLINE void my_atomic_store ## S(                        \
-                     int ## S volatile *a, int ## S v)	\
+                     Uv_ ## S U_a, U_ ## S U_v)                 \
 {                                                               \
   make_atomic_store_body(S);                                    \
 }
@@ -112,19 +157,19 @@ STATIC_INLINE void my_atomic_store ## S(			\
 #else /* no inline functions */
 
 #define make_atomic_add(S)                                      \
-extern int ## S my_atomic_add ## S(int ## S volatile *a, int ## S v);
+extern int ## S my_atomic_add ## S(Uv_ ## S, U_ ## S);
 
 #define make_atomic_fas(S)                                      \
-extern int ## S my_atomic_fas ## S(int ## S volatile *a, int ## S v);
+extern int ## S my_atomic_fas ## S(Uv_ ## S, U_ ## S);
 
 #define make_atomic_cas(S)                                      \
-extern int my_atomic_cas ## S(int ## S volatile *a, int ## S *cmp, int ## S set);
+extern int my_atomic_cas ## S(Uv_ ## S, Uv_ ## S, U_ ## S);
 
 #define make_atomic_load(S)                                     \
-extern int ## S my_atomic_load ## S(int ## S volatile *a);
+extern int ## S my_atomic_load ## S(Uv_ ## S);
 
 #define make_atomic_store(S)                                    \
-extern void my_atomic_store ## S(int ## S volatile *a, int ## S v);
+extern void my_atomic_store ## S(Uv_ ## S, U_ ## S);
 
 #endif
 
@@ -157,6 +202,18 @@ make_atomic_fas(ptr)
 #undef _atomic_h_cleanup_
 #endif
 
+#undef U_8
+#undef U_16
+#undef U_32
+#undef U_ptr
+#undef a
+#undef cmp
+#undef v
+#undef set
+#undef U_a
+#undef U_cmp
+#undef U_v
+#undef U_set
 #undef make_atomic_add
 #undef make_atomic_cas
 #undef make_atomic_load

unittest/mysys/my_atomic-t.c

@@ -21,7 +21,8 @@
 #include <my_atomic.h>
 #include <lf.h>
 
-volatile uint32 a32,b32,c32, N;
+volatile uint32 a32,b32;
+volatile int32  c32, N;
 my_atomic_rwlock_t rwl;
 LF_ALLOCATOR lf_allocator;
 LF_HASH lf_hash;
@@ -98,7 +99,7 @@ pthread_handler_t test_atomic_cas_handler(void *arg)
     x= (x*m+0x87654321) & INT_MAX32;
     do {
       my_atomic_rwlock_wrlock(&rwl);
-      ok= my_atomic_cas32(&a32, &y, y+x);
+      ok= my_atomic_cas32(&a32, &y, (uint32)y+x);
       my_atomic_rwlock_wrunlock(&rwl);
     } while (!ok) ;
     do {