Support textDocument/declaration & LocationLink

textDocument/{declaration,definition,typeDefinition} return either LocationLink[] or Location[]
Add an initialization option client.linkSupport . When it is false, ccls will return Location[] disregarding client's linkSupport.
`struct LocationLink` does not include originSelectionRange as it is wasteful.

src/config.hh

@@ -85,6 +85,8 @@ struct Config {
   struct ClientCapability {
     // TextDocumentClientCapabilities.documentSymbol.hierarchicalDocumentSymbolSupport
     bool hierarchicalDocumentSymbolSupport = true;
+    // TextDocumentClientCapabilities.definition.linkSupport
+    bool linkSupport = true;
     // TextDocumentClientCapabilities.completion.completionItem.snippetSupport
     bool snippetSupport = true;
   } client;
@@ -260,30 +262,28 @@ struct Config {
   } xref;
 };
 REFLECT_STRUCT(Config::Clang, excludeArgs, extraArgs, pathMappings,
-                    resourceDir);
+               resourceDir);
 REFLECT_STRUCT(Config::ClientCapability, hierarchicalDocumentSymbolSupport,
-                    snippetSupport);
+               linkSupport, snippetSupport);
 REFLECT_STRUCT(Config::CodeLens, localVariables);
 REFLECT_STRUCT(Config::Completion::Include, blacklist, maxPathSize,
-                    suffixWhitelist, whitelist);
+               suffixWhitelist, whitelist);
 REFLECT_STRUCT(Config::Completion, caseSensitivity, detailedLabel,
-                    dropOldRequests, duplicateOptional, filterAndSort, include,
+               dropOldRequests, duplicateOptional, filterAndSort, include,
-                    maxNum);
+               maxNum);
 REFLECT_STRUCT(Config::Diagnostics, blacklist, onChange, onOpen, onSave,
-                    spellChecking, whitelist)
+               spellChecking, whitelist)
-REFLECT_STRUCT(Config::Highlight, largeFileSize, lsRanges, blacklist,
+REFLECT_STRUCT(Config::Highlight, largeFileSize, lsRanges, blacklist, whitelist)
-                    whitelist)
 REFLECT_STRUCT(Config::Index, blacklist, comments, initialBlacklist,
-                    initialWhitelist, multiVersion, multiVersionBlacklist,
+               initialWhitelist, multiVersion, multiVersionBlacklist,
-                    multiVersionWhitelist, onChange, threads, trackDependency,
+               multiVersionWhitelist, onChange, threads, trackDependency,
-                    whitelist);
+               whitelist);
 REFLECT_STRUCT(Config::Session, maxNum);
 REFLECT_STRUCT(Config::WorkspaceSymbol, caseSensitivity, maxNum, sort);
 REFLECT_STRUCT(Config::Xref, maxNum);
-REFLECT_STRUCT(Config, compilationDatabaseCommand,
+REFLECT_STRUCT(Config, compilationDatabaseCommand, compilationDatabaseDirectory,
-                    compilationDatabaseDirectory, cacheDirectory, cacheFormat,
+               cacheDirectory, cacheFormat, clang, client, codeLens, completion,
-                    clang, client, codeLens, completion, diagnostics, highlight,
+               diagnostics, highlight, index, session, workspaceSymbol, xref);
-                    index, session, workspaceSymbol, xref);
 
 extern Config *g_config;
 

src/lsp.cc

@@ -60,10 +60,6 @@ DocumentUri DocumentUri::FromPath(const std::string &path) {
   return result;
 }
 
-bool DocumentUri::operator==(const DocumentUri &other) const {
-  return raw_uri == other.raw_uri;
-}
-
 void DocumentUri::SetPath(const std::string &path) {
   // file:///c%3A/Users/jacob/Desktop/superindex/indexer/full_tests
   raw_uri = path;

src/lsp.hh

@@ -72,7 +72,8 @@ constexpr char window_showMessage[] = "window/showMessage";
 struct DocumentUri {
   static DocumentUri FromPath(const std::string &path);
 
-  bool operator==(const DocumentUri &other) const;
+  bool operator==(const DocumentUri &o) const { return raw_uri == o.raw_uri; }
+  bool operator<(const DocumentUri &o) const { return raw_uri < o.raw_uri; }
 
   void SetPath(const std::string &path);
   std::string GetPath() const;
@@ -119,8 +120,26 @@ struct Location {
     return uri == o.uri && range == o.range;
   }
   bool operator<(const Location &o) const {
-    return !(uri.raw_uri == o.uri.raw_uri) ? uri.raw_uri < o.uri.raw_uri
+    return !(uri == o.uri) ? uri < o.uri : range < o.range;
-                                           : range < o.range;
+  }
+};
+
+struct LocationLink {
+  std::string targetUri;
+  lsRange targetRange;
+  lsRange targetSelectionRange;
+  explicit operator bool() const { return targetUri.size(); }
+  explicit operator Location() && {
+    return {DocumentUri{std::move(targetUri)}, targetSelectionRange};
+  }
+  bool operator==(const LocationLink &o) const {
+    return targetUri == o.targetUri &&
+           targetSelectionRange == o.targetSelectionRange;
+  }
+  bool operator<(const LocationLink &o) const {
+    return !(targetUri == o.targetUri)
+               ? targetUri < o.targetUri
+               : targetSelectionRange < o.targetSelectionRange;
   }
 };
 

src/message_handler.cc

@@ -116,6 +116,21 @@ void ReplyOnce::NotReady(bool file) {
     Error(ErrorCode::InternalError, "not indexed");
 }
 
+void ReplyOnce::ReplyLocationLink(std::vector<LocationLink> &result) {
+  std::sort(result.begin(), result.end());
+  result.erase(std::unique(result.begin(), result.end()), result.end());
+  if (result.size() > g_config->xref.maxNum)
+    result.resize(g_config->xref.maxNum);
+  if (g_config->client.linkSupport) {
+    (*this)(result);
+  } else {
+    std::vector<Location> result1;
+    for (auto &loc : result)
+      result1.emplace_back(std::move(loc));
+    (*this)(result1);
+  }
+}
+
 void MessageHandler::Bind(const char *method,
                           void (MessageHandler::*handler)(JsonReader &)) {
   method2notification[method] = [this, handler](JsonReader &reader) {
@@ -155,6 +170,7 @@ void MessageHandler::Bind(const char *method,
 }
 
 MessageHandler::MessageHandler() {
+  // clang-format off
   Bind("$ccls/call", &MessageHandler::ccls_call);
   Bind("$ccls/fileInfo", &MessageHandler::ccls_fileInfo);
   Bind("$ccls/info", &MessageHandler::ccls_info);
@@ -169,39 +185,31 @@ MessageHandler::MessageHandler() {
   Bind("textDocument/codeAction", &MessageHandler::textDocument_codeAction);
   Bind("textDocument/codeLens", &MessageHandler::textDocument_codeLens);
   Bind("textDocument/completion", &MessageHandler::textDocument_completion);
+  Bind("textDocument/declaration", &MessageHandler::textDocument_declaration);
   Bind("textDocument/definition", &MessageHandler::textDocument_definition);
   Bind("textDocument/didChange", &MessageHandler::textDocument_didChange);
   Bind("textDocument/didClose", &MessageHandler::textDocument_didClose);
   Bind("textDocument/didOpen", &MessageHandler::textDocument_didOpen);
   Bind("textDocument/didSave", &MessageHandler::textDocument_didSave);
-  Bind("textDocument/documentHighlight",
+  Bind("textDocument/documentHighlight", &MessageHandler::textDocument_documentHighlight);
-       &MessageHandler::textDocument_documentHighlight);
   Bind("textDocument/documentLink", &MessageHandler::textDocument_documentLink);
-  Bind("textDocument/documentSymbol",
+  Bind("textDocument/documentSymbol", &MessageHandler::textDocument_documentSymbol);
-       &MessageHandler::textDocument_documentSymbol);
   Bind("textDocument/foldingRange", &MessageHandler::textDocument_foldingRange);
   Bind("textDocument/formatting", &MessageHandler::textDocument_formatting);
   Bind("textDocument/hover", &MessageHandler::textDocument_hover);
-  Bind("textDocument/implementation",
+  Bind("textDocument/implementation", &MessageHandler::textDocument_implementation);
-       &MessageHandler::textDocument_implementation);
+  Bind("textDocument/onTypeFormatting", &MessageHandler::textDocument_onTypeFormatting);
-  Bind("textDocument/onTypeFormatting",
+  Bind("textDocument/rangeFormatting", &MessageHandler::textDocument_rangeFormatting);
-       &MessageHandler::textDocument_onTypeFormatting);
-  Bind("textDocument/rangeFormatting",
-       &MessageHandler::textDocument_rangeFormatting);
   Bind("textDocument/references", &MessageHandler::textDocument_references);
   Bind("textDocument/rename", &MessageHandler::textDocument_rename);
-  Bind("textDocument/signatureHelp",
+  Bind("textDocument/signatureHelp", &MessageHandler::textDocument_signatureHelp);
-       &MessageHandler::textDocument_signatureHelp);
+  Bind("textDocument/typeDefinition", &MessageHandler::textDocument_typeDefinition);
-  Bind("textDocument/typeDefinition",
+  Bind("workspace/didChangeConfiguration", &MessageHandler::workspace_didChangeConfiguration);
-       &MessageHandler::textDocument_typeDefinition);
+  Bind("workspace/didChangeWatchedFiles", &MessageHandler::workspace_didChangeWatchedFiles);
-  Bind("workspace/didChangeConfiguration",
+  Bind("workspace/didChangeWorkspaceFolders", &MessageHandler::workspace_didChangeWorkspaceFolders);
-       &MessageHandler::workspace_didChangeConfiguration);
-  Bind("workspace/didChangeWatchedFiles",
-       &MessageHandler::workspace_didChangeWatchedFiles);
-  Bind("workspace/didChangeWorkspaceFolders",
-       &MessageHandler::workspace_didChangeWorkspaceFolders);
   Bind("workspace/executeCommand", &MessageHandler::workspace_executeCommand);
   Bind("workspace/symbol", &MessageHandler::workspace_symbol);
+  // clang-format on
 }
 
 void MessageHandler::Run(InMessage &msg) {

src/message_handler.hh

@@ -189,6 +189,7 @@ REFLECT_STRUCT(ResponseError, code, message);
 REFLECT_STRUCT(Position, line, character);
 REFLECT_STRUCT(lsRange, start, end);
 REFLECT_STRUCT(Location, uri, range);
+REFLECT_STRUCT(LocationLink, targetUri, targetRange, targetSelectionRange);
 REFLECT_UNDERLYING_B(SymbolKind);
 REFLECT_STRUCT(TextDocumentIdentifier, uri);
 REFLECT_STRUCT(TextDocumentItem, uri, languageId, version, text);
@@ -210,6 +211,7 @@ struct ReplyOnce {
       pipeline::ReplyError(id, [&](JsonWriter &w) { Reflect(w, err); });
   }
   void NotReady(bool file);
+  void ReplyLocationLink(std::vector<LocationLink> &result);
 };
 
 struct MessageHandler {
@@ -252,6 +254,7 @@ private:
   void textDocument_codeAction(CodeActionParam &, ReplyOnce &);
   void textDocument_codeLens(TextDocumentParam &, ReplyOnce &);
   void textDocument_completion(CompletionParam &, ReplyOnce &);
+  void textDocument_declaration(TextDocumentPositionParam &, ReplyOnce &);
   void textDocument_definition(TextDocumentPositionParam &, ReplyOnce &);
   void textDocument_didChange(TextDocumentDidChangeParam &);
   void textDocument_didClose(TextDocumentParam &);

src/messages/ccls_vars.cc

@@ -51,12 +51,14 @@ void MessageHandler::ccls_vars(JsonReader &reader, ReplyOnce &reply) {
       usr = def->type;
       [[fallthrough]];
     }
-    case Kind::Type:
+    case Kind::Type: {
-      result = GetLsLocations(
+      for (DeclRef dr :
-          db, wfiles,
+           GetVarDeclarations(db, db->Type(usr).instances, param.kind))
-          GetVarDeclarations(db, db->Type(usr).instances, param.kind));
+        if (auto loc = GetLocationLink(db, wfiles, dr))
+          result.push_back(Location(std::move(loc)));
       break;
     }
+    }
   }
   reply(result);
 }

src/messages/initialize.cc

@@ -173,6 +173,11 @@ struct TextDocumentClientCap {
     } completionItem;
   } completion;
 
+  // Ignore declaration, implementation, typeDefinition
+  struct LinkSupport {
+    bool linkSupport = false;
+  } definition;
+
   struct DocumentSymbol {
     bool hierarchicalDocumentSymbolSupport = false;
   } documentSymbol;
@@ -183,7 +188,8 @@ REFLECT_STRUCT(TextDocumentClientCap::Completion::CompletionItem,
 REFLECT_STRUCT(TextDocumentClientCap::Completion, completionItem);
 REFLECT_STRUCT(TextDocumentClientCap::DocumentSymbol,
                hierarchicalDocumentSymbolSupport);
-REFLECT_STRUCT(TextDocumentClientCap, completion, documentSymbol);
+REFLECT_STRUCT(TextDocumentClientCap::LinkSupport, linkSupport);
+REFLECT_STRUCT(TextDocumentClientCap, completion, definition, documentSymbol);
 
 struct ClientCap {
   WorkspaceClientCap workspace;
@@ -284,11 +290,13 @@ void Initialize(MessageHandler *m, InitializeParam &param, ReplyOnce &reply) {
 
   // Client capabilities
   const auto &capabilities = param.capabilities;
-  g_config->client.snippetSupport &=
-      capabilities.textDocument.completion.completionItem.snippetSupport;
   g_config->client.hierarchicalDocumentSymbolSupport &=
       capabilities.textDocument.documentSymbol
           .hierarchicalDocumentSymbolSupport;
+  g_config->client.linkSupport &=
+      capabilities.textDocument.definition.linkSupport;
+  g_config->client.snippetSupport &=
+      capabilities.textDocument.completion.completionItem.snippetSupport;
 
   // Ensure there is a resource directory.
   if (g_config->clang.resourceDir.empty())

src/messages/textDocument_definition.cc

@@ -45,6 +45,27 @@ std::vector<DeclRef> GetNonDefDeclarationTargets(DB *db, SymbolRef sym) {
 }
 } // namespace
 
+void MessageHandler::textDocument_declaration(TextDocumentPositionParam &param,
+                                              ReplyOnce &reply) {
+  int file_id;
+  QueryFile *file = FindFile(param.textDocument.uri.GetPath(), &file_id);
+  WorkingFile *wf = file ? wfiles->GetFile(file->def->path) : nullptr;
+  if (!wf) {
+    reply.NotReady(file);
+    return;
+  }
+
+  std::vector<LocationLink> result;
+  Position &ls_pos = param.position;
+  for (SymbolRef sym : FindSymbolsAtLocation(wf, file, param.position))
+    for (DeclRef dr : GetNonDefDeclarations(db, sym))
+      if (!(dr.file_id == file_id &&
+            dr.range.Contains(ls_pos.line, ls_pos.character)))
+        if (auto loc = GetLocationLink(db, wfiles, dr))
+          result.push_back(loc);
+  reply.ReplyLocationLink(result);
+}
+
 void MessageHandler::textDocument_definition(TextDocumentPositionParam &param,
                                              ReplyOnce &reply) {
   int file_id;
@@ -55,54 +76,52 @@ void MessageHandler::textDocument_definition(TextDocumentPositionParam &param,
     return;
   }
 
-  std::vector<Location> result;
+  std::vector<LocationLink> result;
-  Maybe<Use> on_def;
+  Maybe<DeclRef> on_def;
   Position &ls_pos = param.position;
 
   for (SymbolRef sym : FindSymbolsAtLocation(wf, file, ls_pos, true)) {
     // Special cases which are handled:
     //  - symbol has declaration but no definition (ie, pure virtual)
     //  - goto declaration while in definition of recursive type
-    std::vector<Use> uses;
+    std::vector<DeclRef> drs;
     EachEntityDef(db, sym, [&](const auto &def) {
       if (def.spell) {
-        Use spell = *def.spell;
+        DeclRef spell = *def.spell;
         if (spell.file_id == file_id &&
             spell.range.Contains(ls_pos.line, ls_pos.character)) {
           on_def = spell;
-          uses.clear();
+          drs.clear();
           return false;
         }
-        uses.push_back(spell);
+        drs.push_back(spell);
       }
       return true;
     });
 
     // |uses| is empty if on a declaration/definition, otherwise it includes
     // all declarations/definitions.
-    if (uses.empty()) {
+    if (drs.empty()) {
-      for (Use use : GetNonDefDeclarationTargets(db, sym))
+      for (DeclRef dr : GetNonDefDeclarationTargets(db, sym))
-        if (!(use.file_id == file_id &&
+        if (!(dr.file_id == file_id &&
-              use.range.Contains(ls_pos.line, ls_pos.character)))
+              dr.range.Contains(ls_pos.line, ls_pos.character)))
-          uses.push_back(use);
+          drs.push_back(dr);
       // There is no declaration but the cursor is on a definition.
-      if (uses.empty() && on_def)
+      if (drs.empty() && on_def)
-        uses.push_back(*on_def);
+        drs.push_back(*on_def);
     }
-    auto locs = GetLsLocations(db, wfiles, uses);
+    for (DeclRef dr : drs)
-    result.insert(result.end(), locs.begin(), locs.end());
+      if (auto loc = GetLocationLink(db, wfiles, dr))
+        result.push_back(loc);
   }
 
-  if (result.size()) {
+  if (result.empty()) {
-    std::sort(result.begin(), result.end());
-    result.erase(std::unique(result.begin(), result.end()), result.end());
-  } else {
     Maybe<Range> range;
     // Check #include
     for (const IndexInclude &include : file->def->includes) {
       if (include.line == ls_pos.line) {
         result.push_back(
-            Location{DocumentUri::FromPath(include.resolved_path)});
+            {DocumentUri::FromPath(include.resolved_path).raw_uri});
         range = {{0, 0}, {0, 0}};
         break;
       }
@@ -160,13 +179,13 @@ void MessageHandler::textDocument_definition(TextDocumentPositionParam &param,
       if (best_sym.kind != Kind::Invalid) {
         Maybe<DeclRef> dr = GetDefinitionSpell(db, best_sym);
         assert(dr);
-        if (auto loc = GetLsLocation(db, wfiles, *dr))
+        if (auto loc = GetLocationLink(db, wfiles, *dr))
-          result.push_back(*loc);
+          result.push_back(loc);
       }
     }
   }
 
-  reply(result);
+  reply.ReplyLocationLink(result);
 }
 
 void MessageHandler::textDocument_typeDefinition(
@@ -178,17 +197,16 @@ void MessageHandler::textDocument_typeDefinition(
     return;
   }
 
-  std::vector<Location> result;
+  std::vector<LocationLink> result;
   auto Add = [&](const QueryType &type) {
     for (const auto &def : type.def)
-      if (def.spell) {
+      if (def.spell)
-        if (auto ls_loc = GetLsLocation(db, wfiles, *def.spell))
+        if (auto loc = GetLocationLink(db, wfiles, *def.spell))
-          result.push_back(*ls_loc);
+          result.push_back(loc);
-      }
     if (result.empty())
       for (const DeclRef &dr : type.declarations)
-        if (auto ls_loc = GetLsLocation(db, wfiles, dr))
+        if (auto loc = GetLocationLink(db, wfiles, dr))
-          result.push_back(*ls_loc);
+          result.push_back(loc);
   };
   for (SymbolRef sym : FindSymbolsAtLocation(wf, file, param.position)) {
     switch (sym.kind) {
@@ -211,8 +229,6 @@ void MessageHandler::textDocument_typeDefinition(
     }
   }
 
-  std::sort(result.begin(), result.end());
+  reply.ReplyLocationLink(result);
-  result.erase(std::unique(result.begin(), result.end()), result.end());
-  reply(result);
 }
 } // namespace ccls

src/query.cc

@@ -532,9 +532,9 @@ std::vector<Use> GetFuncDeclarations(DB *db, const std::vector<Usr> &usrs) {
 std::vector<Use> GetTypeDeclarations(DB *db, const std::vector<Usr> &usrs) {
   return GetDeclarations(db->type_usr, db->types, usrs);
 }
-std::vector<Use> GetVarDeclarations(DB *db, const std::vector<Usr> &usrs,
+std::vector<DeclRef> GetVarDeclarations(DB *db, const std::vector<Usr> &usrs,
-                                    unsigned kind) {
+                                        unsigned kind) {
-  std::vector<Use> ret;
+  std::vector<DeclRef> ret;
   ret.reserve(usrs.size());
   for (Usr usr : usrs) {
     QueryVar &var = db->Var(usr);
@@ -681,17 +681,18 @@ std::optional<Location> GetLsLocation(DB *db, WorkingFiles *wfiles,
   return GetLsLocation(db, wfiles, Use{{sym.range, sym.role}, file_id});
 }
 
-std::vector<Location> GetLsLocations(DB *db, WorkingFiles *wfiles,
+LocationLink GetLocationLink(DB *db, WorkingFiles *wfiles, DeclRef dr) {
-                                     const std::vector<Use> &uses) {
+  std::string path;
-  std::vector<Location> ret;
+  DocumentUri uri = GetLsDocumentUri(db, dr.file_id, &path);
-  for (Use use : uses)
+  if (auto range = GetLsRange(wfiles->GetFile(path), dr.range))
-    if (auto loc = GetLsLocation(db, wfiles, use))
+    if (auto extent = GetLsRange(wfiles->GetFile(path), dr.extent)) {
-      ret.push_back(*loc);
+      LocationLink ret;
-  std::sort(ret.begin(), ret.end());
+      ret.targetUri = uri.raw_uri;
-  ret.erase(std::unique(ret.begin(), ret.end()), ret.end());
+      ret.targetSelectionRange = *range;
-  if (ret.size() > g_config->xref.maxNum)
+      ret.targetRange = extent->Includes(*range) ? *extent : *range;
-    ret.resize(g_config->xref.maxNum);
+      return ret;
-  return ret;
+    }
+  return {};
 }
 
 SymbolKind GetSymbolKind(DB *db, SymbolIdx sym) {

src/query.hh

@@ -200,7 +200,7 @@ Maybe<DeclRef> GetDefinitionSpell(DB *db, SymbolIdx sym);
 // for each id.
 std::vector<Use> GetFuncDeclarations(DB *, const std::vector<Usr> &);
 std::vector<Use> GetTypeDeclarations(DB *, const std::vector<Usr> &);
-std::vector<Use> GetVarDeclarations(DB *, const std::vector<Usr> &, unsigned);
+std::vector<DeclRef> GetVarDeclarations(DB *, const std::vector<Usr> &, unsigned);
 
 // Get non-defining declarations.
 std::vector<DeclRef> &GetNonDefDeclarations(DB *db, SymbolIdx sym);
@@ -215,8 +215,8 @@ DocumentUri GetLsDocumentUri(DB *db, int file_id);
 std::optional<Location> GetLsLocation(DB *db, WorkingFiles *wfiles, Use use);
 std::optional<Location> GetLsLocation(DB *db, WorkingFiles *wfiles,
                                         SymbolRef sym, int file_id);
-std::vector<Location> GetLsLocations(DB *db, WorkingFiles *wfiles,
+LocationLink GetLocationLink(DB *db, WorkingFiles *wfiles, DeclRef dr);
-                                           const std::vector<Use> &uses);
+
 // Returns a symbol. The symbol will *NOT* have a location assigned.
 std::optional<SymbolInformation> GetSymbolInfo(DB *db, SymbolIdx sym,
                                                  bool detailed);