__DECLARE_FLEX_ARRAY(T, member) macro expands to
struct {
struct {} __empty_member;
T member[];
};
which is subtly wrong in C++ because sizeof(struct{}) is 1 not 0,
changing UAPI structures layouts.
This can be fixed by expanding simply to
T member[];
Most of the usages still be broken because of other C++ shenanigans
but this fixes simplest usage: 1 flexible member at the end.
Fix header guard while I'm at it.
Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
---
include/uapi/linux/stddef.h | 6 ++++++
1 file changed, 6 insertions(+)
--- a/include/uapi/linux/stddef.h
+++ b/include/uapi/linux/stddef.h
@@ -39,6 +39,10 @@
* struct, it needs to be wrapped in an anonymous struct with at least 1
* named member, but that member can be empty.
*/
+#ifdef __cplusplus
+#define __DECLARE_FLEX_ARRAY(T, member) \
+ T member[]
+#else
#define __DECLARE_FLEX_ARRAY(TYPE, NAME) \
struct { \
struct { } __empty_ ## NAME; \
@@ -49,3 +53,5 @@
#ifndef __counted_by
#define __counted_by(m)
#endif
+
+#endif
