What caused the following aggregate initialization problem?

Question

I am trying to reproduce the code explained in a textbook about learning c++. The simplest one is given as follows. But it does not compile as expected.

#include<vector>

using namespace std;

struct Storage
{
 vector<int> data;
};

Storage GetStorage(vector<int> params)
{
    return Storage{ .data=params};
}

Intellisense gives me this error back:

Storege{(<error-type>)<error-constant>}
expected an expression C/C++(29)

@Brian: Could you elaborate more about it? I don't understand why `Storage` is not an aggregate. — Second Person Shooter, Mar 28 '21 at 13:38
You may want to read [What are Aggregates and PODs and how/why are they special?](https://stackoverflow.com/questions/4178175/what-are-aggregates-and-pods-and-how-why-are-they-special). — Brian61354270, Mar 28 '21 at 13:39
@Brian: That link clearly explains why `Storage` _is_ an aggregate. — Peter, Mar 28 '21 at 13:45
@Peter Gah, so it is. For some reason I was thinking aggregates had to be trivial. That's what I get for commenting before the coffee kicks in. I'll leave my comments as they are in case they help someone else learn from my confusion. — Brian61354270, Mar 28 '21 at 13:50
Images cannot be indexed, serached by their content or be read by screen readers used by visually impared folks. — StoryTeller - Unslander Monica, Mar 28 '21 at 14:04
@StoryTeller-UnslanderMonica: It does make sense. Thank you! — Second Person Shooter, Mar 28 '21 at 14:13
@MoneySetsYouFree [Why not upload images of code/errors when asking a question?](https://meta.stackoverflow.com/questions/285551/wh-not-upload-images-of-code-errors-when-asking-a-question) — François Andrieux, Mar 28 '21 at 15:03
The most appropriate reason not to upload image is "every time an image of code is uploaded, a kitten somewhere dies.". Unfortunately, I uploaded an error message that none wants to copy and paste. — Second Person Shooter, Mar 28 '21 at 15:15

Guillaume Racicot · Accepted Answer · 2021-03-28T14:04:39.127

2

You must set your language version to C++20 for designated initializers to work. On visual studio you must enable the flag /std:c++latest and -std=c++20 on other compilers

edited Mar 28 '21 at 14:04

answered Mar 28 '21 at 13:39

Guillaume Racicot

39,621
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Does this actually fix the issue? I thought C++20's designated initializers only applied to aggregates. – Brian61354270 Mar 28 '21 at 13:42
@Brian it is an aggregate – Guillaume Racicot Mar 28 '21 at 13:42

What caused the following aggregate initialization problem?

1 Answers1