Deduced values in function contraints are not available inside the function?

[TurkeyMan]

I find I have to do this sort of thing fairly often:

T endianToNative(T, bool little)(ref const ubyte[T.sizeof] bytes)
    if (is(T == U[N], U, size_t N))
{
    // repeat function constraint inside static if to capture U and N
    static if (is(T == U[N], U, size_t N))
    {
        // use `U`, `N`...
    }
}

You can see here I write a static-if repeating the function constraint so I can refer to U and N inside the function.
Is there a reason why deduced material from function constraints are not made available to the function?

[Herringway]

Something like this?

T endianToNative(T : U[N], bool little, U, size_t N)(ref const ubyte[T.sizeof] bytes)
{
	// use `U`, `N`...
}

[TurkeyMan]

Doesn't that mean T can implicitly convert to a U[N], or does colon mean == in this case?
But even so, it sucks that U and N are now mangled into the function as additional template args; that's not a good thing.
I stand by my OP...