utf8ToUtf16LeStringLiteralImpl

fn utf8ToUtf16LeStringLiteralImpl(comptime utf8: []const u8, comptime surrogates: Surrogates) *const [calcUtf16LeLenImpl(utf8, surrogates) catch |err| @compileError(err):0]u16 {
    return comptime blk: {
        const len: usize = calcUtf16LeLenImpl(utf8, surrogates) catch unreachable;
        var utf16le: [len:0]u16 = @splat(0);
        const utf16le_len = utf8ToUtf16LeImpl(&utf16le, utf8[0..], surrogates) catch |err| @compileError(err);
        assert(len == utf16le_len);
        const final = utf16le;
        break :blk &final;
    };
}