How to explain this syntax?

[Andy via Gcc-help <gcc-help@xxxxxxxxxxx>]

In gcc/gcc/testsuite/gcc.c-torture/compile/pr43635.c
we have

extern void d (void);

void (*foo (void)) (float)
{
  void (*(*x) (void)) (float) = d;
  return (*x) ();
}

d is a function without parameters and nothing returns.
foo is function without parameters and returns pointer to function with one
parameter float and also returning void?
what is type of x?
void (*(*x) (void)) (float) is on whole type definition of x or part is
type definition of x and part is cast d to x? which parts?
why not returns x but (*x) ()? don' t return pointer to function but call
this function?
I know, this is malignant example, in in real world can't be cast function
returning void to function returning value