[clangd] Support outgoing calls in call hierarchy (llvm#77556)

Co-authored-by: Quentin Chateau <quentin.chateau@gmail.com>

Author: HighCommander4

clang-tools-extra/clangd/ClangdLSPServer.cpp

@@ -1415,6 +1415,12 @@ void ClangdLSPServer::onInlayHint(const InlayHintsParams &Params,
                      std::move(Reply));
 }
 
+void ClangdLSPServer::onCallHierarchyOutgoingCalls(
+    const CallHierarchyOutgoingCallsParams &Params,
+    Callback<std::vector<CallHierarchyOutgoingCall>> Reply) {
+  Server->outgoingCalls(Params.item, std::move(Reply));
+}
+
 void ClangdLSPServer::applyConfiguration(
     const ConfigurationSettings &Settings) {
   // Per-file update to the compilation database.
@@ -1693,6 +1699,7 @@ void ClangdLSPServer::bindMethods(LSPBinder &Bind,
   Bind.method("typeHierarchy/subtypes", this, &ClangdLSPServer::onSubTypes);
   Bind.method("textDocument/prepareCallHierarchy", this, &ClangdLSPServer::onPrepareCallHierarchy);
   Bind.method("callHierarchy/incomingCalls", this, &ClangdLSPServer::onCallHierarchyIncomingCalls);
+  Bind.method("callHierarchy/outgoingCalls", this, &ClangdLSPServer::onCallHierarchyOutgoingCalls);
   Bind.method("textDocument/selectionRange", this, &ClangdLSPServer::onSelectionRange);
   Bind.method("textDocument/documentLink", this, &ClangdLSPServer::onDocumentLink);
   Bind.method("textDocument/semanticTokens/full", this, &ClangdLSPServer::onSemanticTokens);

clang-tools-extra/clangd/ClangdLSPServer.h

@@ -156,6 +156,9 @@ class ClangdLSPServer : private ClangdServer::Callbacks,
   void onCallHierarchyIncomingCalls(
       const CallHierarchyIncomingCallsParams &,
       Callback<std::vector<CallHierarchyIncomingCall>>);
+  void onCallHierarchyOutgoingCalls(
+      const CallHierarchyOutgoingCallsParams &,
+      Callback<std::vector<CallHierarchyOutgoingCall>>);
   void onClangdInlayHints(const InlayHintsParams &,
                           Callback<llvm::json::Value>);
   void onInlayHint(const InlayHintsParams &, Callback<std::vector<InlayHint>>);

clang-tools-extra/clangd/ClangdServer.cpp

@@ -912,6 +912,15 @@ void ClangdServer::inlayHints(PathRef File, std::optional<Range> RestrictRange,
   WorkScheduler->runWithAST("InlayHints", File, std::move(Action), Transient);
 }
 
+void ClangdServer::outgoingCalls(
+    const CallHierarchyItem &Item,
+    Callback<std::vector<CallHierarchyOutgoingCall>> CB) {
+  WorkScheduler->run("Outgoing Calls", "",
+                     [CB = std::move(CB), Item, this]() mutable {
+                       CB(clangd::outgoingCalls(Item, Index));
+                     });
+}
+
 void ClangdServer::onFileEvent(const DidChangeWatchedFilesParams &Params) {
   // FIXME: Do nothing for now. This will be used for indexing and potentially
   // invalidating other caches.

clang-tools-extra/clangd/ClangdServer.h

@@ -292,6 +292,10 @@ class ClangdServer {
   void incomingCalls(const CallHierarchyItem &Item,
                      Callback<std::vector<CallHierarchyIncomingCall>>);
 
+  /// Resolve outgoing calls for a given call hierarchy item.
+  void outgoingCalls(const CallHierarchyItem &Item,
+                     Callback<std::vector<CallHierarchyOutgoingCall>>);
+
   /// Resolve inlay hints for a given document.
   void inlayHints(PathRef File, std::optional<Range> RestrictRange,
                   Callback<std::vector<InlayHint>>);

clang-tools-extra/clangd/XRefs.cpp

@@ -1702,6 +1702,7 @@ declToHierarchyItem(const NamedDecl &ND, llvm::StringRef TUPath) {
 
   HierarchyItem HI;
   HI.name = printName(Ctx, ND);
+  // FIXME: Populate HI.detail the way we do in symbolToHierarchyItem?
   HI.kind = SK;
   HI.range = Range{sourceLocToPosition(SM, DeclRange->getBegin()),
                    sourceLocToPosition(SM, DeclRange->getEnd())};
@@ -1753,6 +1754,7 @@ static std::optional<HierarchyItem> symbolToHierarchyItem(const Symbol &S,
   }
   HierarchyItem HI;
   HI.name = std::string(S.Name);
+  HI.detail = (S.Scope + S.Name).str();
   HI.kind = indexSymbolKindToSymbolKind(S.SymInfo.Kind);
   HI.selectionRange = Loc->range;
   // FIXME: Populate 'range' correctly
@@ -2319,6 +2321,63 @@ incomingCalls(const CallHierarchyItem &Item, const SymbolIndex *Index) {
   return Results;
 }
 
+std::vector<CallHierarchyOutgoingCall>
+outgoingCalls(const CallHierarchyItem &Item, const SymbolIndex *Index) {
+  std::vector<CallHierarchyOutgoingCall> Results;
+  if (!Index || Item.data.empty())
+    return Results;
+  auto ID = SymbolID::fromStr(Item.data);
+  if (!ID) {
+    elog("outgoingCalls failed to find symbol: {0}", ID.takeError());
+    return Results;
+  }
+  // In this function, we find outgoing calls based on the index only.
+  ContainedRefsRequest Request;
+  Request.ID = *ID;
+  // Initially store the ranges in a map keyed by SymbolID of the callee.
+  // This allows us to group different calls to the same function
+  // into the same CallHierarchyOutgoingCall.
+  llvm::DenseMap<SymbolID, std::vector<Range>> CallsOut;
+  // We can populate the ranges based on a refs request only. As we do so, we
+  // also accumulate the callee IDs into a lookup request.
+  LookupRequest CallsOutLookup;
+  Index->containedRefs(Request, [&](const auto &R) {
+    auto Loc = indexToLSPLocation(R.Location, Item.uri.file());
+    if (!Loc) {
+      elog("outgoingCalls failed to convert location: {0}", Loc.takeError());
+      return;
+    }
+    auto It = CallsOut.try_emplace(R.Symbol, std::vector<Range>{}).first;
+    It->second.push_back(Loc->range);
+
+    CallsOutLookup.IDs.insert(R.Symbol);
+  });
+  // Perform the lookup request and combine its results with CallsOut to
+  // get complete CallHierarchyOutgoingCall objects.
+  Index->lookup(CallsOutLookup, [&](const Symbol &Callee) {
+    // The containedRefs request should only return symbols which are
+    // function-like, i.e. symbols for which references to them can be "calls".
+    using SK = index::SymbolKind;
+    auto Kind = Callee.SymInfo.Kind;
+    assert(Kind == SK::Function || Kind == SK::InstanceMethod ||
+           Kind == SK::ClassMethod || Kind == SK::StaticMethod ||
+           Kind == SK::Constructor || Kind == SK::Destructor ||
+           Kind == SK::ConversionFunction);
+
+    auto It = CallsOut.find(Callee.ID);
+    assert(It != CallsOut.end());
+    if (auto CHI = symbolToCallHierarchyItem(Callee, Item.uri.file()))
+      Results.push_back(
+          CallHierarchyOutgoingCall{std::move(*CHI), std::move(It->second)});
+  });
+  // Sort results by name of the callee.
+  llvm::sort(Results, [](const CallHierarchyOutgoingCall &A,
+                         const CallHierarchyOutgoingCall &B) {
+    return A.to.name < B.to.name;
+  });
+  return Results;
+}
+
 llvm::DenseSet<const Decl *> getNonLocalDeclRefs(ParsedAST &AST,
                                                  const FunctionDecl *FD) {
   if (!FD->hasBody())

clang-tools-extra/clangd/XRefs.h

@@ -150,6 +150,9 @@ prepareCallHierarchy(ParsedAST &AST, Position Pos, PathRef TUPath);
 std::vector<CallHierarchyIncomingCall>
 incomingCalls(const CallHierarchyItem &Item, const SymbolIndex *Index);
 
+std::vector<CallHierarchyOutgoingCall>
+outgoingCalls(const CallHierarchyItem &Item, const SymbolIndex *Index);
+
 /// Returns all decls that are referenced in the \p FD except local symbols.
 llvm::DenseSet<const Decl *> getNonLocalDeclRefs(ParsedAST &AST,
                                                  const FunctionDecl *FD);

clang-tools-extra/clangd/index/Index.cpp

@@ -66,6 +66,11 @@ bool SwapIndex::refs(const RefsRequest &R,
                      llvm::function_ref<void(const Ref &)> CB) const {
   return snapshot()->refs(R, CB);
 }
+bool SwapIndex::containedRefs(
+    const ContainedRefsRequest &R,
+    llvm::function_ref<void(const ContainedRefsResult &)> CB) const {
+  return snapshot()->containedRefs(R, CB);
+}
 void SwapIndex::relations(
     const RelationsRequest &R,
     llvm::function_ref<void(const SymbolID &, const Symbol &)> CB) const {

clang-tools-extra/clangd/index/Index.h

@@ -77,13 +77,34 @@ struct RefsRequest {
   bool WantContainer = false;
 };
 
+struct ContainedRefsRequest {
+  /// Note that RefKind::Call just restricts the matched SymbolKind to
+  /// functions, not the form of the reference (e.g. address-of-function,
+  /// which can indicate an indirect call, should still be caught).
+  static const RefKind SupportedRefKinds = RefKind::Call;
+
+  SymbolID ID;
+  /// If set, limit the number of refers returned from the index. The index may
+  /// choose to return less than this, e.g. it tries to avoid returning stale
+  /// results.
+  std::optional<uint32_t> Limit;
+};
+
 struct RelationsRequest {
   llvm::DenseSet<SymbolID> Subjects;
   RelationKind Predicate;
   /// If set, limit the number of relations returned from the index.
   std::optional<uint32_t> Limit;
 };
 
+struct ContainedRefsResult {
+  /// The source location where the symbol is named.
+  SymbolLocation Location;
+  RefKind Kind = RefKind::Unknown;
+  /// The ID of the symbol which is referred to
+  SymbolID Symbol;
+};
+
 /// Describes what data is covered by an index.
 ///
 /// Indexes may contain symbols but not references from a file, etc.
@@ -141,6 +162,17 @@ class SymbolIndex {
   virtual bool refs(const RefsRequest &Req,
                     llvm::function_ref<void(const Ref &)> Callback) const = 0;
 
+  /// Find all symbols that are referenced by a symbol and apply
+  /// \p Callback on each result.
+  ///
+  /// Results should be returned in arbitrary order.
+  /// The returned result must be deep-copied if it's used outside Callback.
+  ///
+  /// Returns true if there will be more results (limited by Req.Limit);
+  virtual bool containedRefs(
+      const ContainedRefsRequest &Req,
+      llvm::function_ref<void(const ContainedRefsResult &)> Callback) const = 0;
+
   /// Finds all relations (S, P, O) stored in the index such that S is among
   /// Req.Subjects and P is Req.Predicate, and invokes \p Callback for (S, O) in
   /// each.
@@ -175,6 +207,9 @@ class SwapIndex : public SymbolIndex {
               llvm::function_ref<void(const Symbol &)>) const override;
   bool refs(const RefsRequest &,
             llvm::function_ref<void(const Ref &)>) const override;
+  bool containedRefs(
+      const ContainedRefsRequest &,
+      llvm::function_ref<void(const ContainedRefsResult &)>) const override;
   void relations(const RelationsRequest &,
                  llvm::function_ref<void(const SymbolID &, const Symbol &)>)
       const override;

clang-tools-extra/clangd/index/MemIndex.cpp

@@ -9,6 +9,7 @@
 #include "MemIndex.h"
 #include "FuzzyMatch.h"
 #include "Quality.h"
+#include "index/Index.h"
 #include "support/Trace.h"
 
 namespace clang {
@@ -85,6 +86,25 @@ bool MemIndex::refs(const RefsRequest &Req,
   return false; // We reported all refs.
 }
 
+bool MemIndex::containedRefs(
+    const ContainedRefsRequest &Req,
+    llvm::function_ref<void(const ContainedRefsResult &)> Callback) const {
+  trace::Span Tracer("MemIndex refersTo");
+  uint32_t Remaining = Req.Limit.value_or(std::numeric_limits<uint32_t>::max());
+  for (const auto &Pair : Refs) {
+    for (const auto &R : Pair.second) {
+      if (!static_cast<int>(ContainedRefsRequest::SupportedRefKinds & R.Kind) ||
+          Req.ID != R.Container)
+        continue;
+      if (Remaining == 0)
+        return true; // More refs were available.
+      --Remaining;
+      Callback({R.Location, R.Kind, Pair.first});
+    }
+  }
+  return false; // We reported all refs.
+}
+
 void MemIndex::relations(
     const RelationsRequest &Req,
     llvm::function_ref<void(const SymbolID &, const Symbol &)> Callback) const {

clang-tools-extra/clangd/index/MemIndex.h

@@ -72,6 +72,10 @@ class MemIndex : public SymbolIndex {
   bool refs(const RefsRequest &Req,
             llvm::function_ref<void(const Ref &)> Callback) const override;
 
+  bool containedRefs(const ContainedRefsRequest &Req,
+                     llvm::function_ref<void(const ContainedRefsResult &)>
+                         Callback) const override;
+
   void relations(const RelationsRequest &Req,
                  llvm::function_ref<void(const SymbolID &, const Symbol &)>
                      Callback) const override;

clang-tools-extra/clangd/index/Merge.cpp

@@ -155,6 +155,40 @@ bool MergedIndex::refs(const RefsRequest &Req,
   return More || StaticHadMore;
 }
 
+bool MergedIndex::containedRefs(
+    const ContainedRefsRequest &Req,
+    llvm::function_ref<void(const ContainedRefsResult &)> Callback) const {
+  trace::Span Tracer("MergedIndex refersTo");
+  bool More = false;
+  uint32_t Remaining = Req.Limit.value_or(std::numeric_limits<uint32_t>::max());
+  // We don't want duplicated refs from the static/dynamic indexes,
+  // and we can't reliably deduplicate them because offsets may differ slightly.
+  // We consider the dynamic index authoritative and report all its refs,
+  // and only report static index refs from other files.
+  More |= Dynamic->containedRefs(Req, [&](const auto &O) {
+    Callback(O);
+    assert(Remaining != 0);
+    --Remaining;
+  });
+  if (Remaining == 0 && More)
+    return More;
+  auto DynamicContainsFile = Dynamic->indexedFiles();
+  // We return less than Req.Limit if static index returns more refs for dirty
+  // files.
+  bool StaticHadMore = Static->containedRefs(Req, [&](const auto &O) {
+    if ((DynamicContainsFile(O.Location.FileURI) & IndexContents::References) !=
+        IndexContents::None)
+      return; // ignore refs that have been seen from dynamic index.
+    if (Remaining == 0) {
+      More = true;
+      return;
+    }
+    --Remaining;
+    Callback(O);
+  });
+  return More || StaticHadMore;
+}
+
 llvm::unique_function<IndexContents(llvm::StringRef) const>
 MergedIndex::indexedFiles() const {
   return [DynamicContainsFile{Dynamic->indexedFiles()},

clang-tools-extra/clangd/index/Merge.h

@@ -38,6 +38,9 @@ class MergedIndex : public SymbolIndex {
               llvm::function_ref<void(const Symbol &)>) const override;
   bool refs(const RefsRequest &,
             llvm::function_ref<void(const Ref &)>) const override;
+  bool containedRefs(
+      const ContainedRefsRequest &,
+      llvm::function_ref<void(const ContainedRefsResult &)>) const override;
   void relations(const RelationsRequest &,
                  llvm::function_ref<void(const SymbolID &, const Symbol &)>)
       const override;

clang-tools-extra/clangd/index/ProjectAware.cpp

@@ -35,6 +35,10 @@ class ProjectAwareIndex : public SymbolIndex {
   /// Query all indexes while prioritizing the associated one (if any).
   bool refs(const RefsRequest &Req,
             llvm::function_ref<void(const Ref &)> Callback) const override;
+  /// Query all indexes while prioritizing the associated one (if any).
+  bool containedRefs(const ContainedRefsRequest &Req,
+                     llvm::function_ref<void(const ContainedRefsResult &)>
+                         Callback) const override;
 
   /// Queries only the associates index when Req.RestrictForCodeCompletion is
   /// set, otherwise queries all.
@@ -94,6 +98,15 @@ bool ProjectAwareIndex::refs(
   return false;
 }
 
+bool ProjectAwareIndex::containedRefs(
+    const ContainedRefsRequest &Req,
+    llvm::function_ref<void(const ContainedRefsResult &)> Callback) const {
+  trace::Span Tracer("ProjectAwareIndex::refersTo");
+  if (auto *Idx = getIndex())
+    return Idx->containedRefs(Req, Callback);
+  return false;
+}
+
 bool ProjectAwareIndex::fuzzyFind(
     const FuzzyFindRequest &Req,
     llvm::function_ref<void(const Symbol &)> Callback) const {

clang-tools-extra/clangd/index/Ref.h

@@ -63,6 +63,9 @@ enum class RefKind : uint8_t {
   //   ^ this references Foo, but does not explicitly spell out its name
   // };
   Spelled = 1 << 3,
+  // A reference which is a call. Used as a filter for which references
+  // to store in data structures used for computing outgoing calls.
+  Call = 1 << 4,
   All = Declaration | Definition | Reference | Spelled,
 };