Windows: Fixing Windows C++ compilation issues with unnamed structure

MSVC does not allow to redefine unnamed structure in union.
Thus, this fix defines the struct outside of the anonymous union
in order to calculate the padded size.

Signed-off-by: Shireesh Kumar Singh <[email protected]>
Co-authored-by:Sairam Venugopal <[email protected]>
Signed-off-by: Ben Pfaff <[email protected]>

include/openvswitch/util.h

@@ -185,11 +185,11 @@ OVS_NO_RETURN void ovs_assert_failure(const char *, const char *, const char *);
 /* C++ doesn't allow a type declaration within "sizeof", but it does support
  * scoping for member names, so we can just declare a second member, with a
  * name and the same type, and then use its size. */
-#define PADDED_MEMBERS(UNIT, MEMBERS)                           \
-    union {                                                     \
-        struct { MEMBERS };                                     \
-        struct { MEMBERS } named_member__;                      \
-        uint8_t PAD_ID[ROUND_UP(sizeof named_member__, UNIT)];  \
+#define PADDED_MEMBERS(UNIT, MEMBERS)                                       \
+    struct named_member__ { MEMBERS };                                      \
+    union {                                                                 \
+        struct { MEMBERS };                                                 \
+        uint8_t PAD_ID[ROUND_UP(sizeof(struct named_member__), UNIT)];      \
     }
 #endif
 
@@ -233,11 +233,11 @@ OVS_NO_RETURN void ovs_assert_failure(const char *, const char *, const char *);
     }
 #else
 #define PADDED_MEMBERS_CACHELINE_MARKER(UNIT, CACHELINE, MEMBERS)           \
+    struct struct_##CACHELINE { MEMBERS };                                  \
     union {                                                                 \
         OVS_CACHE_LINE_MARKER CACHELINE;                                    \
         struct { MEMBERS };                                                 \
-        struct { MEMBERS } named_member_##CACHELINE;                        \
-        uint8_t PAD_ID[ROUND_UP(sizeof named_member_##CACHELINE, UNIT)];    \
+        uint8_t PAD_ID[ROUND_UP(sizeof(struct struct_##CACHELINE), UNIT)];  \
     }
 #endif