[clangd] Call hierarchy (ClangdServer layer)

[kadircet]

can you also add some tests to ClangdTests.cpp ?

clang-tools-extra/clangd/ClangdServer.cpp

696

why do we run this on the mainthread ? I suppose we should just do WorkScheduler.run

702

can we reply with none/empty at clangdlsplayer directly and delete the outgoingCalls from both clangdserver and xrefs.cpp ?

[nridge]

Address review comments

[nridge]

In D91123#2387032, @kadircet wrote:

can you also add some tests to ClangdTests.cpp ?

It seems like they would be highly duplicative of the tests in CallHierarchyTests.cpp.

clang-tools-extra/clangd/ClangdServer.cpp

696

I was following what resolveTypeHierarchy did. Should I change that too?

[kadircet]

clang-tools-extra/clangd/ClangdServer.cpp

696

yes, i think we should. preferably on a different patch though.

[nridge]

Update as per API changes in xrefs patch

clang-tools-extra/clangd/ClangdServer.h

void typeHierarchy(PathRef File, Position Pos, int Resolve,
                      TypeHierarchyDirection Direction,
                      Callback<llvm::Optional<TypeHierarchyItem>> CB);
 
   /// Resolve type hierarchy item in the given direction.
   void resolveTypeHierarchy(TypeHierarchyItem Item, int Resolve,
                             TypeHierarchyDirection Direction,
                             Callback<llvm::Optional<TypeHierarchyItem>> CB);
 
+  /// Get information about call hierarchy for a given position.
+  void prepareCallHierarchy(PathRef File, Position Pos,
+                            Callback<std::vector<CallHierarchyItem>> CB);
+
+  /// Resolve incoming calls for a given call hierarchy item.
+  void incomingCalls(const CallHierarchyItem &Item,
+                     Callback<std::vector<CallHierarchyIncomingCall>>);
+
   /// Retrieve the top symbols from the workspace matching a query.
   void workspaceSymbols(StringRef Query, int Limit,
                         Callback<std::vector<SymbolInformation>> CB);
 
   /// Retrieve the symbols within the specified file.
   void documentSymbols(StringRef File,
                        Callback<std::vector<DocumentSymbol>> CB);
 

clang-tools-extra/clangd/ClangdServer.cpp

 
 void ClangdServer::resolveTypeHierarchy(
     TypeHierarchyItem Item, int Resolve, TypeHierarchyDirection Direction,
     Callback<llvm::Optional<TypeHierarchyItem>> CB) {
   clangd::resolveTypeHierarchy(Item, Resolve, Direction, Index);
   CB(Item);
 }
 
+void ClangdServer::prepareCallHierarchy(
+    PathRef File, Position Pos, Callback<std::vector<CallHierarchyItem>> CB) {
+  auto Action = [File = File.str(), Pos,
+                 CB = std::move(CB)](Expected<InputsAndAST> InpAST) mutable {
+    if (!InpAST)
+      return CB(InpAST.takeError());
+    CB(clangd::prepareCallHierarchy(InpAST->AST, Pos, File));
+  };
+  WorkScheduler.runWithAST("Call Hierarchy", File, std::move(Action));
+}
+
+void ClangdServer::incomingCalls(
+    const CallHierarchyItem &Item,
+    Callback<std::vector<CallHierarchyIncomingCall>> CB) {
+  WorkScheduler.run("Incoming Calls", "",
+                    [CB = std::move(CB), Item, this]() mutable {
+                      CB(clangd::incomingCalls(Item, Index));
+                    });
+}
+
 void ClangdServer::onFileEvent(const DidChangeWatchedFilesParams &Params) {
   // FIXME: Do nothing for now. This will be used for indexing and potentially
   // invalidating other caches.
 }
 
 void ClangdServer::workspaceSymbols(
     llvm::StringRef Query, int Limit,
     Callback<std::vector<SymbolInformation>> CB) {
   WorkScheduler.run(
       "getWorkspaceSymbols", /*Path=*/"",