[clang] [Clang] Implement resolution for CWG1835 (PR #92957)

[Krystian Stasiowski via cfe-commits]

sdkrystian wrote:

> > Per [[basic.lookup.qual.general] p1](http://eel.is/c++draft/basic.lookup.qual.general#1), lookup for a member-qualified name is type-only if it's an identifier followed by ::;
> 
> Per my reading, type-only lookup is performed only for elaborated type specifiers (http://eel.is/c++draft/basic.lookup#elab-1.sentence-1) and base-specifiers (http://eel.is/c++draft/class.derived#general-2.sentence-4). What [basic.lookup.qual.general] p1 describes is much like type-only lookup, but namespaces are considered. Another important difference is that http://eel.is/c++draft/basic.lookup#general-4.sentence-2 does apply to lookup of identifiers followed by `::`.
> 
> Not saying that this materially changes anything, but we should be more cautious with terminology.

Sorry, I used "type-only" there but I intended to write "only considers namespaces, types, and templates whose specializations are types". I'll edit my comment to fix that. The intended phrasing is what I implemented.

https://github.com/llvm/llvm-project/pull/92957