[PATCH v2 10/13] libxc: simplify HYPERCALL_BUFFER()

[Jan Beulich <jbeulich@xxxxxxxx>]

_hcbuf_buf1 has been there only for a pointer comparison to validate
type compatibility. The same can be achieved by not using typeof() on
the definition of what so far was _hcbuf_buf2, as the initializer has
to also be type-compatible. Drop _hcbuf_buf1 and the comaprison;
rename _hcbuf_buf2.

Since we're already using compiler extensions here, don't be shy and
also omit the middle operand of the involved ?: operator.

Bring line continuation character placement in line with that of
related macros.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v2: New.

--- a/tools/include/xenctrl.h
+++ b/tools/include/xenctrl.h
@@ -247,13 +247,10 @@ typedef struct xc_hypercall_buffer xc_hy
 /*
  * Returns the hypercall_buffer associated with a variable.
  */
-#define HYPERCALL_BUFFER(_name)                                 \
-    ({  xc_hypercall_buffer_t _hcbuf_buf1;                      \
-        typeof(XC__HYPERCALL_BUFFER_NAME(_name)) *_hcbuf_buf2 = \
-                &XC__HYPERCALL_BUFFER_NAME(_name);              \
-        (void)(&_hcbuf_buf1 == _hcbuf_buf2);                    \
-        (_hcbuf_buf2)->param_shadow ?                           \
-                (_hcbuf_buf2)->param_shadow : (_hcbuf_buf2);    \
+#define HYPERCALL_BUFFER(_name)                                \
+    ({  xc_hypercall_buffer_t *_hcbuf_buf =                    \
+                &XC__HYPERCALL_BUFFER_NAME(_name);             \
+        _hcbuf_buf->param_shadow ?: _hcbuf_buf;                \
      })
 
 #define HYPERCALL_BUFFER_INIT_NO_BOUNCE .dir = 0, .sz = 0, .ubuf = (void *)-1