[PATCH] D83501: [clangd][ObjC] Improve xrefs for protocols and classes

[Sam McCall via Phabricator via cfe-commits]

sammccall added inline comments.


================
Comment at: clang-tools-extra/clangd/XRefs.cpp:276
        getDeclAtPosition(AST, CurLoc, Relations, NodeKind)) {
     // Special case: void foo() ^override: jump to the overridden method.
     if (const auto *CMD = llvm::dyn_cast<CXXMethodDecl>(D)) {
----------------
dgoldman wrote:
> sammccall wrote:
> > dgoldman wrote:
> > > sammccall wrote:
> > > > dgoldman wrote:
> > > > > Think it would make sense to special case ObjCInterfaceDecl here to get at both the interface definition + implementation if available?
> > > > Rather than returning both results, I think it's more consistent to return them as a declaration/definition pair.
> > > > 
> > > > (This means special-casing ObjCImplDecl in namedDecl or at least getDeclAsPosition, so you always end up with the ObjCInterfaceDecl instead)
> > > Whoops, meant to comment here but it was lost. I'm not sure what you meant here. Should this be done here inside the for loop or in getDeclAtPosition?
> > > 
> > > Are you saying that given:
> > > 
> > > ```
> > > @interface Foo // A
> > > @end
> > > @implementation Foo // B
> > > @end
> > > ```
> > > B --> A here
> > > 
> > > and similarly
> > > 
> > > ```
> > > @interface Foo // A
> > > @end
> > > @interface Foo (Ext) // B
> > > @end
> > > @implementation Foo (Ext) // C
> > > @end
> > > ```
> > > B --> A
> > > C --> B (and A? it's unclear how this should map over, e.g. maybe Foo loc --> A, Ext --> B)
> > In the first example, selecting either A or B should yield one LocatedSymbol with {Decl=A, Def=B}. This shouldn't require any special-casing.
> > 
> > The second example is very similar to template specialization, with exceptions:
> >  - there's always a Decl/Def pair you may want to navigate between, whereas in templates there rarely is, so we have ambiguity
> >  - there's no AST like there is for template names and args, just a bag of tokens
> > 
> > I'd suggest, given `@interface Foo (Ext)`:
> >  - we produce a LocatedSymbol with {Decl=@interface Foo(Ext), Def=@implementation  Foo(Ext)} - this is the default behavior
> >  - if the cursor is exactly on the token `Foo`, we also produce a LocatedSymbol with {Decl=@interface Foo, Def=@implementation Foo} - this is similar to the template special case
> >  - if the cursor is exactly on the token Ext... are categories explicitly/separately declared anywhere? I guess not. If they are, we could special case this too.
> > And `@implementation Foo(Ext)` should behave in exactly the same way.
> Trying this out now, two problems:
> 
> - getDeclAtPosition will call findTarget. Due to the changes above we map `ObjCCategoryImplDecl` to its interface. This is OK but then when we check for the loc it's obviously != to the impl's loc. Should I modify this to check the contents of the loc for equality?
> 
> - We call `getDeclAtPosition` only looking for DeclRelation::TemplatePattern | DeclRelation::Alias, but this is actually a DeclRelation::Underlying. If I don't add that we filter out the ObjCCategoryImplDecl. If I add it we get a failure in LocateSymbol.TemplateTypedef (we now find another symbol, not sure what is intended here)
> 
> 
> getDeclAtPosition will call findTarget. Due to the changes above we map ObjCCategoryImplDecl to its interface. This is OK but then when we check for the loc it's obviously != to the impl's loc. Should I modify this to check the contents of the loc for equality?

Oh right... yes, this seems fine to me (for the ObjCContainerDecl subclasses only, and with a comment) 

> We call getDeclAtPosition only looking for DeclRelation::TemplatePattern | DeclRelation::Alias, but this is actually a DeclRelation::Underlying. If I don't add that we filter out the ObjCCategoryImplDecl. If I add it we get a failure in LocateSymbol.TemplateTypedef (we now find another symbol, not sure what is intended here)

I'm not sure what "this" in "this is actually a DeclRelation::Underlying" refers to. Do you have a failing testcase?


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https://reviews.llvm.org/D83501