Attempt to define safe cast mechanism to remove const and volatile qualifiers.

The mechanism works but only when used inside function.
But the most of problematic assignments are in structures
initializers in our projects.

Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>

diff --git a/ulut/ul_utdefs.h b/ulut/ul_utdefs.h
index 9c38fe5b3b2468fc8141999bd541923cb65e6a41..b00ea9207b41539305555bc0f2defa6417225d09 100644 (file)
--- a/ulut/ul_utdefs.h
+++ b/ulut/ul_utdefs.h
@@ -146,6 +146,31 @@ extern "C" {
 #endif
 #endif /*UL_ATTR_REENTRANT*/
 
+/* The cast idea based on libHX by Jan Engelhardt */
+#define UL_TYPEOF_REFX(ref_asterisks, ptr_type) \
+  typeof(ref_asterisks(union { int z; typeof(ptr_type) x; }){0}.x)
+
+#ifdef __GNUC__
+#define UL_CAST_UNQX(ref_asterisks, new_type, expr) ({ \
+  UL_BUILD_BUG_ON_MSG(!__builtin_types_compatible_p\
+    (UL_TYPEOF_REFX(ref_asterisks, expr), \
+     UL_TYPEOF_REFX(ref_asterisks,new_type)), \
+       "Qualifiers stripping cast to incompatible type"); \
+  (new_type)(expr); \
+})
+#else /*__GNUC__*/
+#define UL_CAST_UNQX(ref_asterisks, new_type, expr) ((new_type)(expr))
+#endif /*__GNUC__*/
+
+#define UL_CAST_UNQ1(new_type, expr) \
+  UL_CAST_UNQX(*, new_type, expr)
+
+#define UL_CAST_UNQ2(new_type, expr) \
+  UL_CAST_UNQX(**, new_type, expr)
+
+#define UL_CAST_UNQ3(new_type, expr) \
+  UL_CAST_UNQX(**, new_type, expr)
+
 #ifdef __cplusplus
 } /* extern "C"*/
 #endif