ccls/src/query_utils.cc

#include "query_utils.h"

#include <climits>

namespace {

// Computes roughly how long |range| is.
int ComputeRangeSize(const Range& range) {
  if (range.start.line != range.end.line)
    return INT_MAX;
  return range.end.column - range.start.column;
}

}  // namespace

optional<QueryLocation> GetDefinitionSpellingOfSymbol(QueryDatabase* db, const QueryTypeId& id) {
  optional<QueryType>& type = db->types[id.id];
  if (type)
    return type->def.definition_spelling;
  return nullopt;
}

optional<QueryLocation> GetDefinitionSpellingOfSymbol(QueryDatabase* db, const QueryFuncId& id) {
  optional<QueryFunc>& func = db->funcs[id.id];
  if (func)
    return func->def.definition_spelling;
  return nullopt;
}

optional<QueryLocation> GetDefinitionSpellingOfSymbol(QueryDatabase* db, const QueryVarId& id) {
  optional<QueryVar>& var = db->vars[id.id];
  if (var)
    return var->def.definition_spelling;
  return nullopt;
}

optional<QueryLocation> GetDefinitionSpellingOfSymbol(QueryDatabase* db, const SymbolIdx& symbol) {
  switch (symbol.kind) {
  case SymbolKind::Type: {
    optional<QueryType>& type = db->types[symbol.idx];
    if (type)
      return type->def.definition_spelling;
    break;
  }
  case SymbolKind::Func: {
    optional<QueryFunc>& func = db->funcs[symbol.idx];
    if (func)
      return func->def.definition_spelling;
    break;
  }
  case SymbolKind::Var: {
    optional<QueryVar>& var = db->vars[symbol.idx];
    if (var)
      return var->def.definition_spelling;
    break;
  }
  case SymbolKind::File:
  case SymbolKind::Invalid: {
    assert(false && "unexpected");
    break;
  }
  }
  return nullopt;
}

optional<QueryLocation> GetDefinitionExtentOfSymbol(QueryDatabase* db, const SymbolIdx& symbol) {
  switch (symbol.kind) {
  case SymbolKind::Type: {
    optional<QueryType>& type = db->types[symbol.idx];
    if (type)
      return type->def.definition_extent;
    break;
  }
  case SymbolKind::Func: {
    optional<QueryFunc>& func = db->funcs[symbol.idx];
    if (func)
      return func->def.definition_extent;
    break;
  }
  case SymbolKind::Var: {
    optional<QueryVar>& var = db->vars[symbol.idx];
    if (var)
      return var->def.definition_extent;
    break;
  }
  case SymbolKind::File: {
    return QueryLocation(QueryFileId(symbol.idx), Range(Position(1, 1), Position(1, 1)));
  }
  case SymbolKind::Invalid: {
    assert(false && "unexpected");
    break;
  }
  }
  return nullopt;
}

std::string GetHoverForSymbol(QueryDatabase* db, const SymbolIdx& symbol) {
  switch (symbol.kind) {
  case SymbolKind::Type: {
    optional<QueryType>& type = db->types[symbol.idx];
    if (type)
      return type->def.detailed_name;
    break;
  }
  case SymbolKind::Func: {
    optional<QueryFunc>& func = db->funcs[symbol.idx];
    if (func)
      return func->def.detailed_name;
    break;
  }
  case SymbolKind::Var: {
    optional<QueryVar>& var = db->vars[symbol.idx];
    if (var)
      return var->def.detailed_name;
    break;
  }
  case SymbolKind::File:
  case SymbolKind::Invalid: {
    assert(false && "unexpected");
    break;
  }
  }
  return "";
}

optional<QueryFileId> GetDeclarationFileForSymbol(QueryDatabase* db, const SymbolIdx& symbol) {
  switch (symbol.kind) {
  case SymbolKind::Type: {
    optional<QueryType>& type = db->types[symbol.idx];
    if (type && type->def.definition_spelling)
      return type->def.definition_spelling->path;
    break;
  }
  case SymbolKind::Func: {
    optional<QueryFunc>& func = db->funcs[symbol.idx];
    if (func) {
      if (!func->declarations.empty())
        return func->declarations[0].path;
      if (func->def.definition_spelling)
        return func->def.definition_spelling->path;
    }
    break;
  }
  case SymbolKind::Var: {
    optional<QueryVar>& var = db->vars[symbol.idx];
    if (var && var->def.definition_spelling)
      return var->def.definition_spelling->path;
    break;
  }
  case SymbolKind::File: {
    return QueryFileId(symbol.idx);
  }
  case SymbolKind::Invalid: {
    assert(false && "unexpected");
    break;
  }
  }
  return nullopt;
}

std::vector<QueryLocation> ToQueryLocation(QueryDatabase* db, const std::vector<QueryFuncRef>& refs) {
  std::vector<QueryLocation> locs;
  locs.reserve(refs.size());
  for (const QueryFuncRef& ref : refs)
    locs.push_back(ref.loc);
  return locs;
}
std::vector<QueryLocation> ToQueryLocation(QueryDatabase* db, const std::vector<QueryTypeId>& ids) {
  std::vector<QueryLocation> locs;
  locs.reserve(ids.size());
  for (const QueryTypeId& id : ids) {
    optional<QueryLocation> loc = GetDefinitionSpellingOfSymbol(db, id);
    if (loc)
      locs.push_back(loc.value());
  }
  return locs;
}
std::vector<QueryLocation> ToQueryLocation(QueryDatabase* db, const std::vector<QueryFuncId>& ids) {
  std::vector<QueryLocation> locs;
  locs.reserve(ids.size());
  for (const QueryFuncId& id : ids) {
    optional<QueryLocation> loc = GetDefinitionSpellingOfSymbol(db, id);
    if (loc)
      locs.push_back(loc.value());
  }
  return locs;
}
std::vector<QueryLocation> ToQueryLocation(QueryDatabase* db, const std::vector<QueryVarId>& ids) {
  std::vector<QueryLocation> locs;
  locs.reserve(ids.size());
  for (const QueryVarId& id : ids) {
    optional<QueryLocation> loc = GetDefinitionSpellingOfSymbol(db, id);
    if (loc)
      locs.push_back(loc.value());
  }
  return locs;
}



std::vector<QueryLocation> GetUsesOfSymbol(QueryDatabase* db, const SymbolIdx& symbol) {
  switch (symbol.kind) {
  case SymbolKind::Type: {
    optional<QueryType>& type = db->types[symbol.idx];
    if (type)
      return type->uses;
    break;
  }
  case SymbolKind::Func: {
    // TODO: the vector allocation could be avoided.
    optional<QueryFunc>& func = db->funcs[symbol.idx];
    if (func) {
      std::vector<QueryLocation> result = ToQueryLocation(db, func->callers);
      AddRange(&result, func->declarations);
      if (func->def.definition_spelling)
        result.push_back(*func->def.definition_spelling);
      return result;
    }
    break;
  }
  case SymbolKind::Var: {
    optional<QueryVar>& var = db->vars[symbol.idx];
    if (var)
      return var->uses;
    break;
  }
  case SymbolKind::File:
  case SymbolKind::Invalid: {
    assert(false && "unexpected");
    break;
  }
  }
  return {};
}

std::vector<QueryLocation> GetDeclarationsOfSymbolForGotoDefinition(QueryDatabase* db, const SymbolIdx& symbol) {
  switch (symbol.kind) {
  case SymbolKind::Type: {
    // Returning the definition spelling of a type is a hack (and is why the
    // function has the postfix `ForGotoDefintion`, but it lets the user
    // jump to the start of a type if clicking goto-definition on the same
    // type from within the type definition.
    optional<QueryType>& type = db->types[symbol.idx];
    if (type) {
      optional<QueryLocation> declaration = type->def.definition_spelling;
      if (declaration)
        return { *declaration };
    }
    break;
  }
  case SymbolKind::Func: {
    optional<QueryFunc>& func = db->funcs[symbol.idx];
    if (func)
      return func->declarations;
    break;
  }
  case SymbolKind::Var: {
    optional<QueryVar>& var = db->vars[symbol.idx];
    if (var) {
      optional<QueryLocation> declaration = var->def.declaration;
      if (declaration)
        return { *declaration };
    }
    break;
  }
  default:
    break;
  }

  return {};
}

optional<QueryLocation> GetBaseDefinitionOrDeclarationSpelling(QueryDatabase* db, QueryFunc& func) {
  if (!func.def.base)
    return nullopt;
  optional<QueryFunc>& base = db->funcs[func.def.base->id];
  if (!base)
    return nullopt;

  auto def = base->def.definition_spelling;
  if (!def && !base->declarations.empty())
    def = base->declarations[0];
  return def;
}

bool HasCallersOnSelfOrBaseOrDerived(QueryDatabase* db, QueryFunc& root) {
  // Check self.
  if (!root.callers.empty())
    return true;

  // Check for base calls.
  optional<QueryFuncId> func_id = root.def.base;
  while (func_id) {
    optional<QueryFunc>& func = db->funcs[func_id->id];
    if (!func)
      break;
    if (!func->callers.empty())
      return true;
    func_id = func->def.base;
  }

  // Check for derived calls.
  std::queue<QueryFuncId> queue;
  PushRange(&queue, root.derived);
  while (!queue.empty()) {
    optional<QueryFunc>& func = db->funcs[queue.front().id];
    queue.pop();
    if (!func)
      continue;

    if (!func->derived.empty())
      return true;
    PushRange(&queue, func->derived);
  }

  return false;
}

std::vector<QueryFuncRef> GetCallersForAllBaseFunctions(QueryDatabase* db, QueryFunc& root) {
  std::vector<QueryFuncRef> callers;

  optional<QueryFuncId> func_id = root.def.base;
  while (func_id) {
    optional<QueryFunc>& func = db->funcs[func_id->id];
    if (!func)
      break;

    AddRange(&callers, func->callers);
    func_id = func->def.base;
  }

  return callers;
}

std::vector<QueryFuncRef> GetCallersForAllDerivedFunctions(QueryDatabase* db, QueryFunc& root) {
  std::vector<QueryFuncRef> callers;

  std::queue<QueryFuncId> queue;
  PushRange(&queue, root.derived);

  while (!queue.empty()) {
    optional<QueryFunc>& func = db->funcs[queue.front().id];
    queue.pop();
    if (!func)
      continue;

    PushRange(&queue, func->derived);
    AddRange(&callers, func->callers);
  }

  return callers;
}

optional<lsPosition> GetLsPosition(WorkingFile* working_file, const Position& position) {
  if (!working_file)
    return lsPosition(position.line - 1, position.column - 1);

  optional<int> start = working_file->GetBufferLineFromIndexLine(position.line);
  if (!start)
    return nullopt;

  return lsPosition(*start - 1, position.column - 1);
}

optional<lsRange> GetLsRange(WorkingFile* working_file, const Range& location) {
  if (!working_file) {
    return lsRange(
      lsPosition(location.start.line - 1, location.start.column - 1),
      lsPosition(location.end.line - 1, location.end.column - 1));
  }

  optional<int> start = working_file->GetBufferLineFromIndexLine(location.start.line);
  optional<int> end = working_file->GetBufferLineFromIndexLine(location.end.line);
  if (!start || !end)
    return nullopt;

  // If remapping end fails (end can never be < start), just guess that the
  // final location didn't move. This only screws up the highlighted code
  // region if we guess wrong, so not a big deal.
  //
  // Remapping fails often in C++ since there are a lot of "};" at the end of
  // class/struct definitions.
  if (*end < *start)
    *end = *start + (location.end.line - location.start.line);

  return lsRange(
    lsPosition(*start - 1, location.start.column - 1),
    lsPosition(*end - 1, location.end.column - 1));
}

lsDocumentUri GetLsDocumentUri(QueryDatabase* db, QueryFileId file_id, std::string* path) {
  optional<QueryFile>& file = db->files[file_id.id];
  if (file) {
    *path = file->def.path;
    return lsDocumentUri::FromPath(*path);
  }
  else {
    *path = "";
    return lsDocumentUri::FromPath("");
  }
}

lsDocumentUri GetLsDocumentUri(QueryDatabase* db, QueryFileId file_id) {
  optional<QueryFile>& file = db->files[file_id.id];
  if (file) {
    return lsDocumentUri::FromPath(file->def.path);
  }
  else {
    return lsDocumentUri::FromPath("");
  }
}

optional<lsLocation> GetLsLocation(QueryDatabase* db, WorkingFiles* working_files, const QueryLocation& location) {
  std::string path;
  lsDocumentUri uri = GetLsDocumentUri(db, location.path, &path);
  optional<lsRange> range = GetLsRange(working_files->GetFileByFilename(path), location.range);
  if (!range)
    return nullopt;
  return lsLocation(uri, *range);
}

NonElidedVector<lsLocation> GetLsLocations(QueryDatabase* db, WorkingFiles* working_files, const std::vector<QueryLocation>& locations) {
  std::unordered_set<lsLocation> unique_locations;
  for (const QueryLocation& query_location : locations) {
    optional<lsLocation> location = GetLsLocation(db, working_files, query_location);
    if (!location)
      continue;
    unique_locations.insert(*location);
  }

  NonElidedVector<lsLocation> result;
  result.reserve(unique_locations.size());
  result.assign(unique_locations.begin(), unique_locations.end());
  return result;
}

// Returns a symbol. The symbol will have *NOT* have a location assigned.
optional<lsSymbolInformation> GetSymbolInfo(QueryDatabase* db, WorkingFiles* working_files, SymbolIdx symbol) {
  switch (symbol.kind) {
  case SymbolKind::File: {
    optional<QueryFile>& file = db->files[symbol.idx];
    if (!file)
      return nullopt;

    lsSymbolInformation info;
    info.name = file->def.path;
    info.kind = lsSymbolKind::File;
    return info;
  }
  case SymbolKind::Type: {
    optional<QueryType>& type = db->types[symbol.idx];
    if (!type)
      return nullopt;

    lsSymbolInformation info;
    info.name = type->def.short_name;
    if (type->def.detailed_name != type->def.short_name)
      info.containerName = type->def.detailed_name;
    info.kind = lsSymbolKind::Class;
    return info;
  }
  case SymbolKind::Func: {
    optional<QueryFunc>& func = db->funcs[symbol.idx];
    if (!func)
      return nullopt;

    lsSymbolInformation info;
    info.name = func->def.short_name;
    info.containerName = func->def.detailed_name;
    info.kind = lsSymbolKind::Function;

    if (func->def.declaring_type.has_value()) {
      optional<QueryType>& container = db->types[func->def.declaring_type->id];
      if (container)
        info.kind = lsSymbolKind::Method;
    }

    return info;
  }
  case SymbolKind::Var: {
    optional<QueryVar>& var = db->vars[symbol.idx];
    if (!var)
      return nullopt;

    lsSymbolInformation info;
    info.name += var->def.short_name;
    info.containerName = var->def.detailed_name;
    info.kind = lsSymbolKind::Variable;
    return info;
  }
  case SymbolKind::Invalid: {
    return nullopt;
  }
  };

  return nullopt;
}

void AddCodeLens(
  const char* singular,
  const char* plural,
  CommonCodeLensParams* common,
  QueryLocation loc,
  const std::vector<QueryLocation>& uses,
  optional<QueryLocation> excluded,
  bool force_display) {
  TCodeLens code_lens;
  optional<lsRange> range = GetLsRange(common->working_file, loc.range);
  if (!range)
    return;
  code_lens.range = *range;
  code_lens.command = lsCommand<lsCodeLensCommandArguments>();
  code_lens.command->command = "cquery.showReferences";
  code_lens.command->arguments.uri = GetLsDocumentUri(common->db, loc.path);
  code_lens.command->arguments.position = code_lens.range.start;

  // Add unique uses.
  std::unordered_set<lsLocation> unique_uses;
  for (const QueryLocation& use : uses) {
    if (excluded == use)
      continue;
    optional<lsLocation> location = GetLsLocation(common->db, common->working_files, use);
    if (!location)
      continue;
    unique_uses.insert(*location);
  }
  code_lens.command->arguments.locations.assign(unique_uses.begin(),
    unique_uses.end());

  // User visible label
  size_t num_usages = unique_uses.size();
  code_lens.command->title = std::to_string(num_usages) + " ";
  if (num_usages == 1)
    code_lens.command->title += singular;
  else
    code_lens.command->title += plural;

  if (force_display || unique_uses.size() > 0)
    common->result->push_back(code_lens);
}

lsWorkspaceEdit BuildWorkspaceEdit(QueryDatabase* db, WorkingFiles* working_files, const std::vector<QueryLocation>& locations, const std::string& new_text) {
  std::unordered_map<QueryFileId, lsTextDocumentEdit> path_to_edit;

  for (auto& location : locations) {
    optional<lsLocation> ls_location = GetLsLocation(db, working_files, location);
    if (!ls_location)
      continue;

    if (path_to_edit.find(location.path) == path_to_edit.end()) {
      path_to_edit[location.path] = lsTextDocumentEdit();

      optional<QueryFile>& file = db->files[location.path.id];
      if (!file)
        continue;

      const std::string& path = file->def.path;
      path_to_edit[location.path].textDocument.uri = lsDocumentUri::FromPath(path);

      WorkingFile* working_file = working_files->GetFileByFilename(path);
      if (working_file)
        path_to_edit[location.path].textDocument.version = working_file->version;
    }

    lsTextEdit edit;
    edit.range = ls_location->range;
    edit.newText = new_text;

    // vscode complains if we submit overlapping text edits.
    auto& edits = path_to_edit[location.path].edits;
    if (std::find(edits.begin(), edits.end(), edit) == edits.end())
      edits.push_back(edit);
  }


  lsWorkspaceEdit edit;
  for (const auto& changes : path_to_edit)
    edit.documentChanges.push_back(changes.second);
  return edit;
}

std::vector<SymbolRef> FindSymbolsAtLocation(WorkingFile* working_file, QueryFile* file, lsPosition position) {
  std::vector<SymbolRef> symbols;
  symbols.reserve(1);

  int target_line = position.line + 1;
  int target_column = position.character + 1;
  if (working_file) {
    optional<int> index_line = working_file->GetIndexLineFromBufferLine(target_line);
    if (index_line)
      target_line = *index_line;
  }

  for (const SymbolRef& ref : file->def.all_symbols) {
    if (ref.loc.range.Contains(target_line, target_column))
      symbols.push_back(ref);
  }

  // Order shorter ranges first, since they are more detailed/precise. This is
  // important for macros which generate code so that we can resolving the
  // macro argument takes priority over the entire macro body.
  //
  // Order functions before other types, which makes goto definition work
  // better on constructors.
  std::sort(symbols.begin(), symbols.end(), [](const SymbolRef& a, const SymbolRef& b) {
    int a_size = ComputeRangeSize(a.loc.range);
    int b_size = ComputeRangeSize(b.loc.range);

    if (a_size == b_size)
      return a.idx.kind != b.idx.kind && a.idx.kind == SymbolKind::Func;

    return a_size < b_size;
  });

  return symbols;
}

NonElidedVector<Out_CqueryTypeHierarchyTree::TypeEntry> BuildParentInheritanceHierarchyForType(QueryDatabase* db, WorkingFiles* working_files, QueryTypeId root) {
  optional<QueryType>& root_type = db->types[root.id];
  if (!root_type)
    return {};

  NonElidedVector<Out_CqueryTypeHierarchyTree::TypeEntry> parent_entries;
  parent_entries.reserve(root_type->def.parents.size());

  for (QueryTypeId parent_id : root_type->def.parents) {
    optional<QueryType>& parent_type = db->types[parent_id.id];
    if (!parent_type)
      continue;

    Out_CqueryTypeHierarchyTree::TypeEntry parent_entry;
    parent_entry.name = parent_type->def.detailed_name;
    if (parent_type->def.definition_spelling)
      parent_entry.location = GetLsLocation(db, working_files, *parent_type->def.definition_spelling);
    parent_entry.children = BuildParentInheritanceHierarchyForType(db, working_files, parent_id);

    parent_entries.push_back(parent_entry);
  }

  return parent_entries;
}


optional<Out_CqueryTypeHierarchyTree::TypeEntry> BuildInheritanceHierarchyForType(QueryDatabase* db, WorkingFiles* working_files, QueryTypeId root_id) {
  optional<QueryType>& root_type = db->types[root_id.id];
  if (!root_type)
    return nullopt;

  Out_CqueryTypeHierarchyTree::TypeEntry entry;

  // Name and location.
  entry.name = root_type->def.detailed_name;
  if (root_type->def.definition_spelling)
    entry.location = GetLsLocation(db, working_files, *root_type->def.definition_spelling);

  entry.children.reserve(root_type->derived.size());

  // Base types.
  Out_CqueryTypeHierarchyTree::TypeEntry base;
  base.name = "[[Base]]";
  base.location = entry.location;
  base.children = BuildParentInheritanceHierarchyForType(db, working_files, root_id);
  if (!base.children.empty())
    entry.children.push_back(base);

  // Add derived.
  for (QueryTypeId derived : root_type->derived) {
    auto derived_entry = BuildInheritanceHierarchyForType(db, working_files, derived);
    if (derived_entry)
      entry.children.push_back(*derived_entry);
  }

  return entry;
}


NonElidedVector<Out_CqueryTypeHierarchyTree::TypeEntry> BuildParentInheritanceHierarchyForFunc(QueryDatabase* db, WorkingFiles* working_files, QueryFuncId root) {
  optional<QueryFunc>& root_func = db->funcs[root.id];
  if (!root_func || !root_func->def.base)
    return {};

  optional<QueryFunc>& parent_func = db->funcs[root_func->def.base->id];
  if (!parent_func)
    return {};

  Out_CqueryTypeHierarchyTree::TypeEntry parent_entry;
  parent_entry.name = parent_func->def.detailed_name;
  if (parent_func->def.definition_spelling)
    parent_entry.location = GetLsLocation(db, working_files, *parent_func->def.definition_spelling);
  parent_entry.children = BuildParentInheritanceHierarchyForFunc(db, working_files, *root_func->def.base);

  NonElidedVector<Out_CqueryTypeHierarchyTree::TypeEntry> entries;
  entries.push_back(parent_entry);
  return entries;
}


optional<Out_CqueryTypeHierarchyTree::TypeEntry> BuildInheritanceHierarchyForFunc(QueryDatabase* db, WorkingFiles* working_files, QueryFuncId root_id) {
  optional<QueryFunc>& root_func = db->funcs[root_id.id];
  if (!root_func)
    return nullopt;

  Out_CqueryTypeHierarchyTree::TypeEntry entry;

  // Name and location.
  entry.name = root_func->def.detailed_name;
  if (root_func->def.definition_spelling)
    entry.location = GetLsLocation(db, working_files, *root_func->def.definition_spelling);

  entry.children.reserve(root_func->derived.size());

  // Base types.
  Out_CqueryTypeHierarchyTree::TypeEntry base;
  base.name = "[[Base]]";
  base.location = entry.location;
  base.children = BuildParentInheritanceHierarchyForFunc(db, working_files, root_id);
  if (!base.children.empty())
    entry.children.push_back(base);

  // Add derived.
  for (QueryFuncId derived : root_func->derived) {
    auto derived_entry = BuildInheritanceHierarchyForFunc(db, working_files, derived);
    if (derived_entry)
      entry.children.push_back(*derived_entry);
  }

  return entry;
}

NonElidedVector<Out_CqueryCallTree::CallEntry> BuildInitialCallTree(QueryDatabase* db, WorkingFiles* working_files, QueryFuncId root) {
  optional<QueryFunc>& root_func = db->funcs[root.id];
  if (!root_func)
    return {};
  if (!root_func->def.definition_spelling)
    return {};
  optional<lsLocation> def_loc = GetLsLocation(db, working_files, *root_func->def.definition_spelling);
  if (!def_loc)
    return {};

  Out_CqueryCallTree::CallEntry entry;
  entry.name = root_func->def.short_name;
  entry.usr = root_func->def.usr;
  entry.location = *def_loc;
  entry.hasCallers = HasCallersOnSelfOrBaseOrDerived(db, *root_func);
  NonElidedVector<Out_CqueryCallTree::CallEntry> result;
  result.push_back(entry);
  return result;
}

NonElidedVector<Out_CqueryCallTree::CallEntry> BuildExpandCallTree(QueryDatabase* db, WorkingFiles* working_files, QueryFuncId root) {
  optional<QueryFunc>& root_func = db->funcs[root.id];
  if (!root_func)
    return {};

  auto format_location = [](const lsLocation& location) -> std::string {
    std::string path = location.uri.GetPath();
    size_t last_index = path.find_last_of('/');
    if (last_index != std::string::npos)
      path = path.substr(last_index + 1);

    return path + ":" + std::to_string(location.range.start.line + 1) + ":" + std::to_string(location.range.start.character + 1);
  };

  NonElidedVector<Out_CqueryCallTree::CallEntry> result;
  std::unordered_set<QueryLocation> seen_locations;

  auto handle_caller = [&](const std::string& prefix, QueryFuncRef caller) {
    optional<lsLocation> call_location = GetLsLocation(db, working_files, caller.loc);
    if (!call_location)
      return;

    // TODO: REMOVE |seen_locations| once we fix the querydb update bugs
    // TODO: REMOVE |seen_locations| once we fix the querydb update bugs
    // TODO: REMOVE |seen_locations| once we fix the querydb update bugs
    // TODO: REMOVE |seen_locations| once we fix the querydb update bugs
    // TODO: REMOVE |seen_locations| once we fix the querydb update bugs
    // TODO: REMOVE |seen_locations| once we fix the querydb update bugs
    // TODO: REMOVE |seen_locations| once we fix the querydb update bugs
    // TODO: REMOVE |seen_locations| once we fix the querydb update bugs
    // TODO: REMOVE |seen_locations| once we fix the querydb update bugs
    // TODO: REMOVE |seen_locations| once we fix the querydb update bugs
    // TODO: REMOVE |seen_locations| once we fix the querydb update bugs
    // TODO: REMOVE |seen_locations| once we fix the querydb update bugs
    // TODO: basically, querydb gets duplicate references inserted into it.
    if (!seen_locations.insert(caller.loc).second) {
      std::cerr << "!!!! FIXME DUPLICATE REFERENCE IN QUERYDB" << std::endl;
      return;
    }

    if (caller.has_id()) {
      optional<QueryFunc>& call_func = db->funcs[caller.id_.id];
      if (!call_func)
        return;

      Out_CqueryCallTree::CallEntry call_entry;
      call_entry.name = prefix + call_func->def.short_name + " (" + format_location(*call_location) + ")";
      call_entry.usr = call_func->def.usr;
      call_entry.location = *call_location;
      call_entry.hasCallers = HasCallersOnSelfOrBaseOrDerived(db, *call_func);
      result.push_back(call_entry);
    }
    else {
      // TODO: See if we can do a better job here. Need more information from
      // the indexer.
      Out_CqueryCallTree::CallEntry call_entry;
      call_entry.name = "Likely Constructor";
      call_entry.usr = "no_usr";
      call_entry.location = *call_location;
      call_entry.hasCallers = false;
      result.push_back(call_entry);
    }
  };

  std::vector<QueryFuncRef> base_callers = GetCallersForAllBaseFunctions(db, *root_func);
  std::vector<QueryFuncRef> derived_callers = GetCallersForAllDerivedFunctions(db, *root_func);
  result.reserve(root_func->callers.size() + base_callers.size() + derived_callers.size());

  for (QueryFuncRef caller : root_func->callers)
    handle_caller("", caller);
  for (QueryFuncRef caller : base_callers) {
    // Do not show calls to the base function coming from this function.
    if (caller.id_ == root)
      continue;

    handle_caller("[B] ", caller);
  }
  for (QueryFuncRef caller : derived_callers)
    handle_caller("[D] ", caller);

  return result;
}