Non-const std.container.Array.opIndex and alikes blocks serialization

[monarch_dodra via Digitalmars-d-learn]

On Sunday, 28 September 2014 at 09:04:42 UTC, Nordlöw wrote:
> On Sunday, 28 September 2014 at 08:58:27 UTC, Nordlöw wrote:
>> In my strive to add msgpacking support for std.container.Array 
>> I've been blocked by the fact that std.container.Array.opIndex 
>> only has one overload which is non-const probably because it 
>> returns a ref T. This doesn't place nicely with serialization.
>>
>> Shouldn't inout be used here?
>
> Further I've tried tagging all opIndex in array.d with inout as
>
>     inout ref T opIndex(size_t i) inout
>
> but then I get another error
>
> array.d(479,30): Error: 
> cast(string)this._data.refCountedPayload()._payload[i] is not 
> an lvalue

Probably you want:

ref inout(T) opIndex(size_t i) inout

Instead. What you wrote was basically the same as:
ref T opIndex(size_t i) inout inout

While compiling, the "inout(T)" obtained from "_payload[i]" is 
"value-converted" into a "T" (makes it an lvalue), and then the 
return (which is "ref") fails.

This is the whole "function attributes on left side confusion" - 
fiasco thing...