[clangd] Implement textDocument/codeLens

[Trass3r]

Summary

Co-authored-by: lightmelodies <[e-mail]>

[Trass3r]

"base" refs are only useful on class forward decls
but for some reasons this still shows up on dtor implementations

[Trass3r]

squashed

[Trass3r]

clang-tools-extra/clangd/CodeLens.cpp

86

they still show up on dtor implementations iirc

[Trass3r]

I just searched again and found https://reviews.llvm.org/D91930.
But seems like it never got updated with the latest code featured here. Though looks like the test got dropped.

[nridge]

Haven't had a chance to look at this yet. I do see that the earier implementation in D91930 was the subject of some design discussions about performance with @kadircet, adding him as an additional reviewer.

[Trass3r]

remove bases codelens for classes
fix lit test
exclude self from ref count

https://github.com/clangd/clangd/issues/442#issuecomment-1125056812

[Trass3r]

clang-tools-extra/clangd/CodeLens.cpp

93

As noted in the previous PR it may be of low value, I guess only if override is missing or if it actually hides several functions.

[Trass3r]

clang-tools-extra/clangd/tool/ClangdMain.cpp

348 ↗

(On Diff #473662)

I guess we should rather make it opt-in and gather some feedback.

[Trass3r]

One remaining issue is multiple lenses for template code like

template <int V>
int i = 0;

template int i<0>;
template int i<1>;
template int i<2>;

template <int V>
struct Foo {
    int foo(); // I see 3 codelenses here
};

template struct Foo<0>;
template struct Foo<1>;

int main()
{
    // return Foo<0>().foo() + Foo<1>().foo();
    // return i<0> + i<1> + i<2>;
}

[lightmelodies]

In D131295#3933381, @Trass3r wrote:

One remaining issue is multiple lenses for template code like

template <int V>
int i = 0;

template int i<0>;
template int i<1>;
template int i<2>;

template <int V>
struct Foo {
    int foo(); // I see 3 codelenses here
};

template struct Foo<0>;
template struct Foo<1>;

int main()
{
    // return Foo<0>().foo() + Foo<1>().foo();
    // return i<0> + i<1> + i<2>;
}

Well, multiple lenses occured due to https://github.com/lightmelodies/llvm-project/blob/codelens/clang-tools-extra/clangd/FindSymbols.cpp#L500
And can be fixed by https://github.com/lightmelodies/llvm-project/blob/codelens/clang-tools-extra/clangd/CodeLens.cpp#L69

[Trass3r]

Thanks, it seems to fix the base case, but I still see multiple lenses when I add

template <int V>
int Foo<V>::foo()
{
    return 0;
}

[lightmelodies]

In D131295#3935027, @Trass3r wrote:

Thanks, it seems to fix the base case, but I still see multiple lenses when I add

template <int V>
int Foo<V>::foo()
{
    return 0;
}

Interesting, I see the same issue with DocumentSymbols. Maybe because foo is explicit specialization (though outside Foo<1>) so both check are passed. However I can not find a way to detect such case right now.

[Trass3r]

Yeah quite complex: https://godbolt.org/z/8T5Pqadro

[lightmelodies]

In D131295#3935759, @Trass3r wrote:

Yeah quite complex: https://godbolt.org/z/8T5Pqadro

Not very hard with a track of visited decls. It should also reslove other duplicate codelens.
https://github.com/lightmelodies/llvm-project/blob/b7d664bff5fcafb5a0758b73cd0b77e64cacb03c/clang-tools-extra/clangd/CodeLens.cpp#L69

clang-tools-extra/clangd/CodeLens.cpp

if (!isa<NamespaceDecl, NamespaceAliasDecl>(D)) {
     Data.uri = std::string(Path);
     Results.emplace_back(CodeLens{Range, None, Data});
   }
 
   // handle inheritance codelens directly
   CodeLensArgument Sub, Super;
   if (auto *CXXRD = dyn_cast<CXXRecordDecl>(D)) {
     if (!CXXRD->isEffectivelyFinal()) {
-      Sub.locations =
-
-          lookupIndex(Index, Limit, Path, D, RelationKind::BaseOf);
+      Sub.locations = lookupIndex(Index, Limit, Path, D, RelationKind::BaseOf);
     }
+    // bases codelens is only useful on forward decls
+    if (!CXXRD->isThisDeclarationADefinition()) {
       for (const auto *P : typeParents(CXXRD)) {
         if (auto Loc = declToLocation(P->getCanonicalDecl()))
           Super.locations.emplace_back(*Loc);
       }
+    }
   } else if (auto *CXXMD = dyn_cast<CXXMethodDecl>(D)) {
     if (CXXMD->isVirtual()) {
       Sub.locations =
           lookupIndex(Index, Limit, Path, D, RelationKind::OverriddenBy);
     }
     for (const auto *P : CXXMD->overridden_methods()) {
       if (auto Loc = declToLocation(P->getCanonicalDecl()))
         Super.locations.emplace_back(*Loc);
     }
   }
 
   if (auto Count = Super.locations.size()) {
     Super.position = Range.start;
     Super.uri = std::string(Path);
     Command Cmd;
     Cmd.command = std::string(CodeAction::SHOW_REFERENCES);
-    Cmd.title = std::to_string(Count) + " base";
+    Cmd.title = std::to_string(Count) + " base(s)";
     Cmd.argument = std::move(Super);
     Results.emplace_back(CodeLens{Range, std::move(Cmd), None});
   }
 
   if (auto Count = Sub.locations.size()) {
     Sub.position = Range.start;
     Sub.uri = std::string(Path);
     Command Cmd;
if (Params.data) {
     CodeLensArgument Arg;
     Arg.uri = std::string(Path);
     Arg.position = Pos;
     auto Refs = findReferences(AST, Pos, Limit, Index).References;
     Arg.locations.reserve(Refs.size());
     for (auto &Ref : Refs) {
       Arg.locations.emplace_back(std::move(Ref.Loc));
     }
-    Cmd.title = std::to_string(Refs.size()) + " references";
+    Cmd.title = std::to_string(Refs.size()) + " ref(s)";
     Cmd.argument = std::move(Arg);
     return CodeLens{Params.range, std::move(Cmd), None};
   }
   return error("failed to resolve codelens");
 }
 } // namespace clangd
 } // namespace clang
 No newline at end of file