HeadConst library type (was: "headconst" dynamic arrays?)

[dsimcha]

Have we considered the obvious library head-const solution?

struct HeadConst(T) {
    T __payload;

    T __get() {
        return __payload;
    }

    alias __get this;
}

HeadConst!T headConst(T)(T stuff) { return typeof(return)(stuff); }

Usage:

auto headConstArray = headConst([1, 2, 3]);

The only problem I see is that you'd get unnecessary copying of structs with
postblits.  IMHO, though, the language spec should be relaxed to allow copying to
be elided due to function inlining.