[PATCH] test/input: Fix alignment assertion for doubles

[Thierry Reding]

From: Thierry Reding <treding at nvidia.com>

The code previously tried to compute the offset of a field in the
valuator by subtracting the address of the valuator from the _value_ of
the field (rather than the field's address). The correct way to do it
would have been (note the &'s):

	assert(((void *) &v->axisVal - (void *) v) % sizeof(double) == 0);
	assert(((void *) &v->axes - (void *) v) % sizeof(double) == 0);

That's essentially what the offsetof() macro does. Using offsetof() has
the added benefit of not using void pointer arithmetic and therefore
silencing a warning on some compilers.

Signed-off-by: Thierry Reding <treding at nvidia.com>
---
 test/input.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/input.c b/test/input.c
index 5813e6dc987b..9b5db89919f5 100644
--- a/test/input.c
+++ b/test/input.c
@@ -1390,8 +1390,8 @@ dix_valuator_alloc(void)
         assert(v->numAxes == num_axes);
 #if !defined(__i386__) && !defined(__m68k__) && !defined(__sh__)
         /* must be double-aligned on 64 bit */
-        assert(((void *) v->axisVal - (void *) v) % sizeof(double) == 0);
-        assert(((void *) v->axes - (void *) v) % sizeof(double) == 0);
+        assert(offsetof(struct _ValuatorClassRec, axisVal) % sizeof(double) == 0);
+        assert(offsetof(struct _ValuatorClassRec, axes) % sizeof(double) == 0);
 #endif
         num_axes++;
     }
-- 
1.8.4.2