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authorRusty Russell <rusty@rustcorp.com.au>2012-03-29 14:58:33 +1030
committerRusty Russell <rusty@rustcorp.com.au>2012-03-29 08:18:57 +0200
commitf74ae3257a2edb9756d9f0442c1314306e936759 (patch)
treec2e960788b0385bbe09bfc7705564f85c7a4d355 /lib
parentbe25ab9c8df2f96ee10929fdfee582935b2f0e06 (diff)
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cast: make sure suncc sees a constant.
cast_const() et. al. are supposed to be a constant expression, so you can do things like: static char *p = cast_const(char *, (const char *)"hello"); Unfortunately, a cast to intptr_t and arithmetic makes suncc reject it as a constant expression. We need the cast, because (1) the expression could be a void *, so we can't just add to it, and (2) gcc complains with -Wcast-qual without it. So instead of adding BUILD_BUG_OR_ZERO, we use a ? :, which keeps everyone happy. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (Imported from CCAN commit 74859ab18b10aaf990848e49d7789ff5c6cf96c6) Autobuild-User: Rusty Russell <rusty@rustcorp.com.au> Autobuild-Date: Thu Mar 29 08:18:57 CEST 2012 on sn-devel-104
Diffstat (limited to 'lib')
-rw-r--r--lib/ccan/cast/cast.h20
-rw-r--r--lib/ccan/cast/test/compile_ok-static.c10
2 files changed, 22 insertions, 8 deletions
diff --git a/lib/ccan/cast/cast.h b/lib/ccan/cast/cast.h
index b108b0c864..1f3a7aac1e 100644
--- a/lib/ccan/cast/cast.h
+++ b/lib/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))
/**
diff --git a/lib/ccan/cast/test/compile_ok-static.c b/lib/ccan/cast/test/compile_ok-static.c
new file mode 100644
index 0000000000..98b667e834
--- /dev/null
+++ b/lib/ccan/cast/test/compile_ok-static.c
@@ -0,0 +1,10 @@
+/* OpenIndiana's CC (aka suncc) has issues with constants: make sure
+ * we are one! */
+#include <ccan/cast/cast.h>
+
+static char *p = cast_const(char *, (const char *)"hello");
+
+int main(int argc, char *argv[])
+{
+ return p[0] == argv[0][0];
+}