This commit refactors intra-doc link error reporting to deduplicate code
and decouple error construction from the type of error. This greatly
improves flexibility at each error construction site, while reducing the
complexity of the diagnostic creation.
This commit also rewords the diagnostics for clarity and style:
- Diagnostics should not end in periods.
- It's unnecessary to say "ignoring it". Since this is a warning by
default, it's already clear that the link is ignored.
This commit improves the calculation of code spans for intra-doc
resolution failures. All sugared doc comments should now have the
correct spans, including those where the comment is longer than the
docs.
It also fixes an issue where the spans were calculated incorrectly for
certain unsugared doc comments. The diagnostic will now always use the
span of the attributes, as originally intended.
Fixes#55964.
