X-Git-Url: https://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Fcast%2Fcast.h;h=cd384c4636d8e5a51fa2ba55f97ff162b5dff84a;hp=2fa96445b338f6b6b341b3f2aad122963e91054e;hb=be24e496578d7c03bc2fd6239887266e82c8d6da;hpb=3f4e83d8ac847d6bf0c20e88cdbca535e842a97b

diff --git a/ccan/cast/cast.h b/ccan/cast/cast.h
index 2fa96445..cd384c46 100644
--- a/ccan/cast/cast.h
+++ b/ccan/cast/cast.h
@@ -1,6 +1,8 @@
+/* Licensed under LGPLv2.1+ - see LICENSE file for details */
 #ifndef CCAN_CAST_H
 #define CCAN_CAST_H
 #include "config.h"
+#include <stdint.h>
 #include <ccan/build_assert/build_assert.h>
 
 /**
@@ -13,8 +15,8 @@
  * only differs in signed/unsigned, not in type or const-ness.
  */
 #define cast_signed(type, expr)						\
-	((type)(expr)							\
-	 + BUILD_ASSERT_OR_ZERO(cast_sign_compatible(type, (expr))))
+	(0 ? BUILD_ASSERT_OR_ZERO(cast_sign_compatible(type, (expr))) :	\
+	 (type)(expr))
 
 /**
  * cast_const - remove a const qualifier from a pointer.
@@ -24,6 +26,10 @@
  * This ensures that you are only removing the const qualifier from an
  * expression.  The expression must otherwise match @type.
  *
+ * We cast via intptr_t to suppress gcc's -Wcast-qual (which SAMBA
+ * uses), and via the ? : so Sun CC doesn't complain about the result
+ * not being constant.
+ *
  * If @type is a pointer to a pointer, you must use cast_const2 (etc).
  *
  * Example:
@@ -32,14 +38,14 @@
  *	{
  *		size_t i;
  *		for (i = 0; i < strlen(haystack); i++)
- *		if (memcmp("needle", haystack+i, strlen("needle")) == 0)
- *			return cast_const(char *, haystack+i);
+ *			if (memcmp("needle", haystack+i, strlen("needle")) == 0)
+ *				return cast_const(char *, haystack+i);
  *		return NULL;
  *	}
  */
-#define cast_const(type, expr)					\
-	((type)(expr)						\
-	 + BUILD_ASSERT_OR_ZERO(cast_const_compat1((expr), type)))
+#define cast_const(type, expr)						\
+        (0 ? BUILD_ASSERT_OR_ZERO(cast_const_compat1((expr), type)) :   \
+         (type)(intptr_t)(expr))
 
 /**
  * cast_const2 - remove a const qualifier from a pointer to a pointer.
@@ -49,9 +55,9 @@
  * This ensures that you are only removing the const qualifier from an
  * expression.  The expression must otherwise match @type.
  */
-#define cast_const2(type, expr)					\
-	((type)(expr)						\
-	 + BUILD_ASSERT_OR_ZERO(cast_const_compat2((expr), type)))
+#define cast_const2(type, expr)						\
+        (0 ? BUILD_ASSERT_OR_ZERO(cast_const_compat2((expr), type)) :   \
+	 (type)(intptr_t)(expr))
 
 /**
  * cast_const3 - remove a const from a pointer to a pointer to a pointer..
@@ -61,9 +67,9 @@
  * This ensures that you are only removing the const qualifier from an
  * expression.  The expression must otherwise match @type.
  */
-#define cast_const3(type, expr)					\
-	((type)(expr)						\
-	 + BUILD_ASSERT_OR_ZERO(cast_const_compat3((expr), type)))
+#define cast_const3(type, expr)						\
+        (0 ? BUILD_ASSERT_OR_ZERO(cast_const_compat3((expr), type)) :   \
+	 (type)(intptr_t)(expr))
 
 
 /**
@@ -104,11 +110,11 @@
 	  )
 
 #define cast_const_strip1(expr)			\
-	__typeof__(*(struct { int z; __typeof__(expr) x; }){0}.x)
+	__typeof__(*(union { int z; __typeof__(expr) x; }){0}.x)
 #define cast_const_strip2(expr) \
-	__typeof__(**(struct { int z; __typeof__(expr) x; }){0}.x)
+	__typeof__(**(union { int z; __typeof__(expr) x; }){0}.x)
 #define cast_const_strip3(expr) \
-	__typeof__(***(struct { int z; __typeof__(expr) x; }){0}.x)
+	__typeof__(***(union { int z; __typeof__(expr) x; }){0}.x)
 #define cast_const_compat1(expr, type)					\
 	__builtin_types_compatible_p(cast_const_strip1(expr),		\
 				     cast_const_strip1(type))
@@ -121,11 +127,8 @@
 #else
 #define cast_sign_compatible(type, expr)		\
 	(sizeof(*(type)0) == 1 && sizeof(*(expr)) == 1)
-#define cast_const_compat1(expr, type)		\
-	(sizeof(*(expr)) == sizeof(*(type)0))
-#define cast_const_compat2(expr, type)		\
-	(sizeof(**(expr)) == sizeof(**(type)0))
-#define cast_const_compat3(expr, type)			\
-	(sizeof(***(expr)) == sizeof(***(type)0))
+#define cast_const_compat1(expr, type)		(1)
+#define cast_const_compat2(expr, type)		(1)
+#define cast_const_compat3(expr, type)		(1)
 #endif
 #endif /* CCAN_CAST_H */