Using std::optional template in another optional Elemet of a branched datastructure

Asked Jun 10 '21 at 07:09

Active Jun 22 '21 at 09:42

Viewed 169 times

I have got a branched datstructure, which is mainly build out of structs and Integers. Some Elements are signed with the std::optional template. In the case of an optional struct element, in another struct, which itself is also referenced in another struct as optional, I get the Error:

Error (active) E0135 class "BasicContent" has no member "km"

That's the code producing this error:

#include "stdafx.h"
#include <optional>


using IntType = int;

struct BasicContent {
    IntType Speed;
    std::optional<IntType> km;
};

struct Message {
    std::optional<BasicContent> basicContent;
};

int main()
{
    Message myMessage;
    myMessage.basicContent->km = 5;

    return 0;
}

The weird thing is, that I can run the code and write to all the data, but it keeps showing this error. Also in the watch "km" is shown as nullopt, but in everything is fine. Is there a solution for this or is there something I don't see?

edited Jun 10 '21 at 13:30

asked Jun 10 '21 at 07:09

Gabriel

4

Please add a [minimal reproducible example](https://stackoverflow.com/help/minimal-reproducible-example). – Evg Jun 10 '21 at 07:16
1

Just a guess: `basicContent.km` → `basicContent->km`? – Daniel Langr Jun 10 '21 at 07:23
@DanielLangr unfortunately not. I had it like you suggested, I updated the post. Thanks anyway for the guess. – Gabriel Jun 10 '21 at 13:32
@Evg thanks, i hope it's fine now – Gabriel Jun 10 '21 at 13:33
@Gabriel Cannot reproduce with MSVC: https://godbolt.org/z/876herqrT. What is your MSVC version? Have you enabled C++17 support? – Daniel Langr Jun 10 '21 at 13:34
BTW, is it an Intellisense error or a compiler error? Looks like this: https://developercommunity.visualstudio.com/t/intellisence-e0135-at-struct-in-stdoptional/229541 – Daniel Langr Jun 10 '21 at 13:37
@DanielLangr weird, yes i enabled C++17. Also with just one optional elements it works fine. – Gabriel Jun 10 '21 at 13:42
1

@DanielLangr Yes thanks, I think it is a Intellisense Error, just found the switch to "Build Only" – Gabriel Jun 10 '21 at 13:45

Using std::optional template in another optional Elemet of a branched datastructure

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