[clangd] Find relations in Dex exploration tool.

[usaxena95]

Update error message.

[hokein]

clang-tools-extra/clangd/index/dex/dexp/Dexp.cpp

304

I think dumping the whole symbol ( toYAML(S)) will give us more useful information

[usaxena95]

Addressed comments. Ready to land.

clang-tools-extra/clangd/index/dex/dexp/Dexp.cpp

 //===--- Dexp.cpp - Dex EXPloration tool ------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements a simple interactive tool which can be used to manually
 // evaluate symbol search quality of Clangd index.
 //
 //===----------------------------------------------------------------------===//
 
+#include "index/Index.h"
+#include "index/Relation.h"
 #include "index/Serialization.h"
 #include "index/dex/Dex.h"
 #include "index/remote/Client.h"
 #include "llvm/ADT/ScopeExit.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/LineEditor/LineEditor.h"
 #include "llvm/Support/CommandLine.h"
Index->refs(RefRequest, [&RegexFilter](const Ref &R) {
         return;
       }
       if (RegexFilter.match(U->body()))
         llvm::outs() << R << "\n";
     });
   }
 };
 
+class Relations : public Command {
+  llvm::cl::opt<std::string> ID{
+      "id",
+      llvm::cl::Positional,
+      llvm::cl::desc("Symbol ID of the symbol being queried (hex)."),
+  };
+  llvm::cl::opt<RelationKind> Relation{
+      "relation",
+      llvm::cl::desc("Relation kind for the predicate."),
+      values(clEnumValN(RelationKind::BaseOf, "base_of",
+                        "Find subclasses of a class."),
+             clEnumValN(RelationKind::OverriddenBy, "overridden_by",
+                        "Find methods that overrides a virtual method.")),
+  };
+
+  void run() override {
+    if (ID.getNumOccurrences() == 0 || Relation.getNumOccurrences() == 0) {
+      llvm::errs()
+          << "Missing required argument: please provide id and -relation.\n";
+      return;
+    }
+    RelationsRequest Req;
+    if (ID.getNumOccurrences()) {
+      auto SID = SymbolID::fromStr(ID);
+      if (!SID) {
+        llvm::errs() << llvm::toString(SID.takeError()) << "\n";
+        return;
+      }
+      Req.Subjects.insert(*SID);
+    }
+    Req.Predicate = Relation.getValue();
+    Index->relations(Req, [](const SymbolID &SID, const Symbol &S) {
+      llvm::outs() << S << " defined at: " << S.Definition << "\n";
+    });
+  }
+};
+
 class Export : public Command {
   llvm::cl::opt<IndexFileFormat> Format{
       "format",
       llvm::cl::desc("Format of index export"),
       llvm::cl::values(
           clEnumValN(IndexFileFormat::YAML, "yaml",
                      "human-readable YAML format"),
           clEnumValN(IndexFileFormat::RIFF, "binary", "binary RIFF format")),
struct {
   const char *Name;
   const char *Description;
   std::function<std::unique_ptr<Command>()> Implementation;
 } CommandInfo[] = {
     {"find", "Search for symbols with fuzzyFind", std::make_unique<FuzzyFind>},
     {"lookup", "Dump symbol details by ID or qualified name",
      std::make_unique<Lookup>},
     {"refs", "Find references by ID or qualified name", std::make_unique<Refs>},
+    {"relations", "Find relations by ID and relation kind",
+     std::make_unique<Relations>},
     {"export", "Export index", std::make_unique<Export>},
 };
 
 std::unique_ptr<SymbolIndex> openIndex(llvm::StringRef Index) {
   return Index.startswith("remote:")
              ? remote::getClient(Index.drop_front(strlen("remote:")),
                                  ProjectRoot)
              : loadIndex(Index, /*UseDex=*/true);