cast: make sure suncc sees a constant.

[ccan] / ccan / cast / cast.h

diff --git a/ccan/cast/cast.h b/ccan/cast/cast.h
index b108b0c864d3b0cd07e26a497040537921d674b4..1f3a7aac1e48640f37868c0564e3851e203113e6 100644 (file)
--- a/ccan/cast/cast.h
+++ b/ccan/cast/cast.h
@@ -15,8 +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.
@@ -26,6 +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:
@@ -40,8 +44,8 @@
  *     }
  */
 #define cast_const(type, expr)                                         \
-       ((type)((intptr_t)(expr)                                        \
-               + BUILD_ASSERT_OR_ZERO(cast_const_compat1((expr), type))))
+        (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.
@@ -52,8 +56,8 @@
  * expression.  The expression must otherwise match @type.
  */
 #define cast_const2(type, expr)                                                \
-       ((type)((intptr_t)(expr)                                        \
-               + BUILD_ASSERT_OR_ZERO(cast_const_compat2((expr), type))))
+        (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..
@@ -64,8 +68,8 @@
  * expression.  The expression must otherwise match @type.
  */
 #define cast_const3(type, expr)                                                \
-       ((type)((intptr_t)(expr)                                        \
-               + BUILD_ASSERT_OR_ZERO(cast_const_compat3((expr), type))))
+        (0 ? BUILD_ASSERT_OR_ZERO(cast_const_compat3((expr), type)) :   \
+        (type)(intptr_t)(expr))
 
 
 /**