Explore documentation issues with variables and unnamed struct

[alandefreitas]

In

/// Documentation
constexpr struct
{
} single {};

the documentation is attached to the unnamed struct rather than the variable.

The unnamed struct is also set as implementation defined and not included in the corpus.

We might need extra logic for the variable to inherit the documentation in these cases.

[K-ballo]

That struct is unnamed, not anonymous.

[mizvekov]

The declarator can declare more than one variable, and each variable can receive its own documentation anyway, separate from the classes.

Example: https://compiler-explorer.com/z/P9v3shjcn

/// A test unnamed class.
static struct {
  /// A test field.
  int a;
}
  /// A test variable named 'x'
  x,
  /// A test variable named 'y'
  y;

This case is not too different from the named variant, as you can still obtain the class type using decltype and use that to declare other stuff.

So I don't think it makes sense for the variable to simply inherit the documentation from the class.

That the unnamed struct is marked as implementation defined looks like a separate bug, this could be us treating the class as anonymous (ie lexically declared in another class) rather than simply unnamed.

We can obtain from the AST whether this situation occurs, if the class is declared (or defined) in an elaborated-type-specifier, but I can't see how it would be helpful to reflect that in the documentation.

[alandefreitas]

So I don't think it makes sense for the variable to simply inherit the documentation from the class.

I agree. We just have to tag the issue we have open about it though. Otherwise we'd have conflicting issues.

[alandefreitas]

@mizvekov I merged #1051 but I reopened the issue because it touches on those other points. But I think we can just close this one when we have the three other ones.