Following code should compile, but doesn't.

import std.range;
struct R
{
    @disable this();  // requires explicit initializer

    @property bool empty() const{ return false; }
    @property int front(){ return 0; }
    void popFront(){}

    @property R save(){ return this; }

    int back(){ return 0; }
    void popBack(){}

    int opIndex(size_t n){ return 0; }
    @property size_t length() const { return 0; }
}
static assert(isInputRange!R);
static assert(isForwardRange!R);
static assert(isBidirectionalRange!R);
static assert(isRandomAccessRange!R);