Wdocumentation-pedantic fails to handle \n newline in a description

[RKSimon]

https://clang.godbolt.org/z/fqncE8MT6

We can use <br> to start a newline in a description, but \n gives a warning:

/// Test function
/// \returns Value<br>
///          second line
int foo();

/// Another test function
/// \returns Value\n
///          second line
int bar();

 warning: unknown command tag name [-Wdocumentation-unknown-command]
/// \returns Value\n

CC'ing @aaronpuchert as this will hopefully just be a minor extension to https://reviews.llvm.org/D111190

[aaronpuchert]

We don't have the concept of a zero-argument command yet, but I guess it would be easy to introduce. There are other commands that take no argument but that I treated as VerbatimLineCommand because they're typically on a line of their own (like \private).

[RKSimon]

Thanks @aaronpuchert - this is the only remaining blocker for #35297 - unfortunately we can't easily replace \n with <br> in the code snippets included in the headers without causing issues downstream

[aaronpuchert]

I'll have a look. We actually have a couple of \n in our code base as well, and it should be low-hanging fruit.

[RKSimon]

Thanks for the fast turnaround @aaronpuchert !