Hello,

I can see I was as clear as mud with my explanation -- apologies for
that, so let me try again.

In my original example:

struct monitor {
    struct {
        int width;
        int height
    } virtual;
};

... the members width and height aren't required any more, as they're
actually computable generically, and don't belong in that struct.
Instead, I have separate functions which can provide those values.

So where I have in code, statements such as:

struct monitor *m = this_monitor();
int foo = m->virutal.width;

I want to be able to substitute "m->virtual.width" with a function
call "get_width()" -- which does not involve "struct monitor" at all.
Indeed, the semantic patch I'm trying to apply now looks like this:

@@
struct monitor *m;
@@

- m->virtual.width;
+ get_width();

... and although spatch doesn't tell me of any errors, when I run it
over my codebase, no modifications are made.  So clearly I'm still
doing something wrong.