[PATCH] D68977: [clangd] Report declaration references in findExplicitReferences.

[Ilya Biryukov via Phabricator via cfe-commits]

ilya-biryukov added inline comments.


================
Comment at: clang-tools-extra/clangd/FindTarget.cpp:415
 
 Optional<ReferenceLoc> refInDecl(const Decl *D) {
   struct Visitor : ConstDeclVisitor<Visitor> {
----------------
kadircet wrote:
> ilya-biryukov wrote:
> > hokein wrote:
> > > ilya-biryukov wrote:
> > > > This should return `SmallVector<ReferenceLoc, 2>` now, some declarations can have both decl and non-decl references.
> > > Can you give some examples? It seems that non-decl references are handled by other `refIn*` functions.
> > > 
> > > ```
> > > int Foo = OtherBar; // OtherBar is captured at the momment.
> > > ```
> > ```
> > namespace $1[[a]] = $2[[std]];
> > ```
> > 
> > `$1` is a declaration of a namespace alias.
> > `$2` is a reference to namespace std.
> I was just about to make the same point. After this patch lands I would like to detect `using namespace`s inside function body, and currently there is no way to distinguish between a usingdirective and a namespacealias. Since both is only referencing the target namespace.
> 
> So even if this starts reporting `$2` in the comment above, there should be a difference between that and `$3` in `using namespace $3[[std]];`
That's intentional, though. When we report references, we deliberately leave out information on where it's coming from - otherwise it's hard to encode it.

However, if we really need that, we could also pass a `NamedDecl*` when reporting declarations (that would mean a slightly different interface, though).

We still have some complexity budget in `findExplicitReferences` and we should probably spend it here.
OTOH, adding more stuff will probably bloat it too much, I hope we'll stop there... There will still be cases when one would have to write a separate AST traversal to do more complicated stuff. It's unfortunate that this is twice as expensive, but it shouldn't matter in most cases (e.g. when running inside `Tweak::apply`)

I'd suggest we keep this patch with `IsDecl` flag, but happy to look into your use-case with `using namespaces` more closely...


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  https://reviews.llvm.org/D68977/new/

https://reviews.llvm.org/D68977