Refrain from using nested designators

[kubalaguna]

Hello,

Using this format (nested designator):

 es_event_authentication_t auth = {
      .data.token = &token
}

instead of:

 es_event_authentication_t auth = {
      .data = {.token = &token}
}

causes some compatibility issues on our end.

Would it be possible to add a check to disallow nested designators? If not, could you please try to use the latter format instead?

Example: #252

[russellhancox]

Can you elaborate on what compatibility issues you're having?
Designated initializers are a C99 feature

[kubalaguna]

Build fails with

error: nested designators are a C99 extension [-Werror,-Wc99-designator]

[pmarkowsky]

@kubalaguna is your goal for this issue to prevent this from happening in the future?

We'd need some sort of static analysis framework to add a presubmit check for this pattern. Unfortunately many of the easy ones like semgrep, or codeql don't support Objective-C/C++.

Meta's infer does but admittedly I've not used it.

[kubalaguna]

Yes, if we could prevent it with a presubmit, it would be great. But if it's not easy to do, please just consider not using this pattern.

[pmarkowsky]

I'm going to close the issue as this is complicated for many reasons and look at trying not to use the pattern in the future.