Buffers: Checkpoint before making struct typeinfo flattened and removing need for stack

tests/run/buffmt.pyx

@@ -18,6 +18,20 @@ else:
     current_endian = '>'
     other_endian = '<'
 
+cdef struct align_of_double_helper:
+    char ch
+    double d    
+cdef struct align_of_int_helper:
+    char ch
+    int i
+double_align = sizeof(align_of_double_helper) - sizeof(double)
+int_align = sizeof(align_of_int_helper) - sizeof(int)
+if double_align != 8:
+    raise RuntimeError("Alignment of double is %d on this system, please report to cython-dev for a testcase fix" % double_align)
+if int_align != 4:
+    raise RuntimeError("Alignment of int is %d on this system, please report to cython-dev for a testcase fix" % int_align)
+
+ 
 cdef class MockBuffer:
     cdef Py_ssize_t zero
     cdef Py_ssize_t minusone