Remove unused variables (#5382)

- Fix GenerateTextFromTable (aliasing typo)
- Fix unused variable in idl_gen_dart.cpp
- Fix std::string passing (should be non-const value or const-reference)
- Remove unused variables

include/flatbuffers/code_generators.h

@@ -82,8 +82,8 @@ class BaseGenerator {
  protected:
   BaseGenerator(const Parser &parser, const std::string &path,
                 const std::string &file_name,
-                const std::string qualifying_start,
-                const std::string qualifying_separator)
+                std::string qualifying_start,
+                std::string qualifying_separator)
       : parser_(parser),
         path_(path),
         file_name_(file_name),

include/flatbuffers/idl.h

@@ -790,7 +790,7 @@ class Parser : public ParserState {
 
   StructDef *LookupStruct(const std::string &id) const;
 
-  std::string UnqualifiedName(std::string fullQualifiedName);
+  std::string UnqualifiedName(const std::string &fullQualifiedName);
 
   FLATBUFFERS_CHECKED_ERROR Error(const std::string &msg);
 

src/code_generators.cpp

@@ -72,13 +72,13 @@ const char *BaseGenerator::FlatBuffersGeneratedWarning() {
 std::string BaseGenerator::NamespaceDir(const Parser &parser,
                                         const std::string &path,
                                         const Namespace &ns) {
-  EnsureDirExists(path.c_str());
+  EnsureDirExists(path);
   if (parser.opts.one_file) return path;
   std::string namespace_dir = path;  // Either empty or ends in separator.
   auto &namespaces = ns.components;
   for (auto it = namespaces.begin(); it != namespaces.end(); ++it) {
     namespace_dir += *it + kPathSeparator;
-    EnsureDirExists(namespace_dir.c_str());
+    EnsureDirExists(namespace_dir);
   }
   return namespace_dir;
 }

src/idl_gen_cpp.cpp

@@ -520,7 +520,7 @@ class CppGenerator : public BaseGenerator {
   static std::string TranslateNameSpace(const std::string &qualified_name) {
     std::string cpp_qualified_name = qualified_name;
     size_t start_pos = 0;
-    while ((start_pos = cpp_qualified_name.find(".", start_pos)) !=
+    while ((start_pos = cpp_qualified_name.find('.', start_pos)) !=
            std::string::npos) {
       cpp_qualified_name.replace(start_pos, 1, "::");
     }

src/idl_gen_dart.cpp

@@ -105,10 +105,10 @@ class DartGenerator : public BaseGenerator {
   static std::string ImportAliasName(const std::string &ns) {
     std::string ret;
     ret.assign(ns);
-    size_t pos = ret.find(".");
+    size_t pos = ret.find('.');
     while (pos != std::string::npos) {
       ret.replace(pos, 1, "_");
-      pos = ret.find(".", pos + 1);
+      pos = ret.find('.', pos + 1);
     }
 
     return ret;
@@ -409,23 +409,23 @@ class DartGenerator : public BaseGenerator {
     auto object_namespace = BuildNamespaceName(*struct_def.defined_namespace);
     std::string code;
 
-    auto object_name = struct_def.name;
+    const auto &object_name = struct_def.name;
 
     // Emit constructor
 
     GenDocComment(struct_def.doc_comment, &code, "");
 
-    auto reader_name = "_" + struct_def.name + "Reader";
-    auto builder_name = struct_def.name + "Builder";
-    auto object_builder_name = struct_def.name + "ObjectBuilder";
+    auto reader_name = "_" + object_name + "Reader";
+    auto builder_name = object_name + "Builder";
+    auto object_builder_name = object_name + "ObjectBuilder";
 
     std::string reader_code, builder_code;
 
-    code += "class " + struct_def.name + " {\n";
+    code += "class " + object_name + " {\n";
 
-    code += "  " + struct_def.name + "._(this._bc, this._bcOffset);\n";
+    code += "  " + object_name + "._(this._bc, this._bcOffset);\n";
     if (!struct_def.fixed) {
-      code += "  factory " + struct_def.name + "(List<int> bytes) {\n";
+      code += "  factory " + object_name + "(List<int> bytes) {\n";
       code += "    " + _kFb + ".BufferContext rootRef = new " + _kFb +
               ".BufferContext.fromBytes(bytes);\n";
       code += "    return reader.read(rootRef, 0);\n";
@@ -433,7 +433,7 @@ class DartGenerator : public BaseGenerator {
     }
 
     code += "\n";
-    code += "  static const " + _kFb + ".Reader<" + struct_def.name +
+    code += "  static const " + _kFb + ".Reader<" + object_name +
             "> reader = const " + reader_name + "();\n\n";
 
     code += "  final " + _kFb + ".BufferContext _bc;\n";
@@ -454,7 +454,7 @@ class DartGenerator : public BaseGenerator {
   }
 
   std::string NamespaceAliasFromUnionType(const std::string &in) {
-    if (in.find("_") == std::string::npos) { return in; }
+    if (in.find('_') == std::string::npos) { return in; }
 
     std::stringstream ss(in);
     std::string item;

src/idl_gen_general.cpp

@@ -1611,7 +1611,7 @@ std::string GeneralMakeRule(const Parser &parser, const std::string &path,
   for (auto it = parser.enums_.vec.begin(); it != parser.enums_.vec.end();
        ++it) {
     auto &enum_def = **it;
-    if (make_rule != "") make_rule += " ";
+    if (!make_rule.empty()) make_rule += " ";
     std::string directory =
         BaseGenerator::NamespaceDir(parser, path, *enum_def.defined_namespace);
     make_rule += directory + enum_def.name + lang.file_extension;
@@ -1620,7 +1620,7 @@ std::string GeneralMakeRule(const Parser &parser, const std::string &path,
   for (auto it = parser.structs_.vec.begin(); it != parser.structs_.vec.end();
        ++it) {
     auto &struct_def = **it;
-    if (make_rule != "") make_rule += " ";
+    if (!make_rule.empty()) make_rule += " ";
     std::string directory = BaseGenerator::NamespaceDir(
         parser, path, *struct_def.defined_namespace);
     make_rule += directory + struct_def.name + lang.file_extension;

src/idl_gen_go.cpp

@@ -188,7 +188,7 @@ class GoGenerator : public BaseGenerator {
   }
 
   // A single enum name member.
-  void EnumNameMember(const EnumDef &enum_def, const EnumVal ev,
+  void EnumNameMember(const EnumDef &enum_def, const EnumVal &ev,
                       size_t max_name_length, std::string *code_ptr) {
     std::string &code = *code_ptr;
     code += "\t";
@@ -228,7 +228,7 @@ class GoGenerator : public BaseGenerator {
   }
 
   // A single enum value member.
-  void EnumValueMember(const EnumDef &enum_def, const EnumVal ev,
+  void EnumValueMember(const EnumDef &enum_def, const EnumVal &ev,
                        size_t max_name_length, std::string *code_ptr) {
     std::string &code = *code_ptr;
     code += "\t\"";
@@ -895,7 +895,7 @@ class GoGenerator : public BaseGenerator {
     EndBuilderBody(code_ptr);
   }
   // Begin by declaring namespace and imports.
-  void BeginFile(const std::string name_space_name, const bool needs_imports,
+  void BeginFile(const std::string &name_space_name, const bool needs_imports,
                  const bool is_enum, std::string *code_ptr) {
     std::string &code = *code_ptr;
     code = code + "// Code generated by the FlatBuffers compiler. DO NOT EDIT.\n\n";

src/idl_gen_grpc.cpp

@@ -149,7 +149,7 @@ class FlatBufPrinter : public grpc_generator::Printer {
   }
 
   void Print(const char *s) {
-    if (s == nullptr || std::strlen(s) == 0) { return; }
+    if (s == nullptr || *s == '\0') { return; }
     // Add this string, but for each part separated by \n, add indentation.
     for (;;) {
       // Current indentation.

src/idl_gen_js_ts.cpp

@@ -214,7 +214,7 @@ class JsTsGenerator : public BaseGenerator {
     std::string &code = *code_ptr;
     std::string &exports = *exports_ptr;
     for (auto it = sorted_namespaces.begin(); it != sorted_namespaces.end();
-         it++) {
+         ++it) {
       if (lang_.language == IDLOptions::kTs) {
         if (it->find('.') == std::string::npos) {
           code += "import { flatbuffers } from \"./flatbuffers\"\n";

src/idl_gen_lua.cpp

@@ -88,7 +88,7 @@ namespace lua {
     }
 
     // Begin enum code with a class declaration.
-    void BeginEnum(const std::string class_name, std::string *code_ptr) {
+    void BeginEnum(const std::string &class_name, std::string *code_ptr) {
       std::string &code = *code_ptr;
       code += "local " + class_name + " = {\n";
     }
@@ -683,7 +683,7 @@ namespace lua {
     }
 
     // Begin by declaring namespace and imports.
-    void BeginFile(const std::string name_space_name, const bool needs_imports,
+    void BeginFile(const std::string &name_space_name, const bool needs_imports,
       std::string *code_ptr) {
       std::string &code = *code_ptr;
       code += std::string(Comment) + FlatBuffersGeneratedWarning() + "\n\n";

src/idl_gen_php.cpp

@@ -232,7 +232,6 @@ class PhpGenerator : public BaseGenerator {
   // Get the value of a table's scalar.
   void GetScalarFieldOfTable(const FieldDef &field, std::string *code_ptr) {
     std::string &code = *code_ptr;
-    std::string getter = GenGetter(field.value.type);
 
     code += Indent + "/**\n";
     code += Indent + " * @return " + GenTypeGet(field.value.type) + "\n";

src/idl_gen_python.cpp

@@ -95,7 +95,7 @@ class PythonGenerator : public BaseGenerator {
   }
 
   // Begin enum code with a class declaration.
-  void BeginEnum(const std::string class_name, std::string *code_ptr) {
+  void BeginEnum(const std::string &class_name, std::string *code_ptr) {
     std::string &code = *code_ptr;
     code += "class " + class_name + "(object):\n";
   }
@@ -750,7 +750,7 @@ class PythonGenerator : public BaseGenerator {
   }
 
   // Begin by declaring namespace and imports.
-  void BeginFile(const std::string name_space_name, const bool needs_imports,
+  void BeginFile(const std::string &name_space_name, const bool needs_imports,
                  std::string *code_ptr) {
     std::string &code = *code_ptr;
     code = code + "# " + FlatBuffersGeneratedWarning() + "\n\n";

src/idl_gen_rust.cpp

@@ -449,7 +449,7 @@ class RustGenerator : public BaseGenerator {
     std::stringstream stream;
 
     stream << "::";
-    for (auto d = dst->components.begin(); d != dst->components.end(); d++) {
+    for (auto d = dst->components.begin(); d != dst->components.end(); ++d) {
       stream << MakeSnakeCase(*d) + "::";
     }
     return stream.str();
@@ -481,15 +481,15 @@ class RustGenerator : public BaseGenerator {
       if (s == src->components.end()) { break; }
       if (d == dst->components.end()) { break; }
       if (*s != *d) { break; }
-      s++;
-      d++;
-      i++;
+      ++s;
+      ++d;
+      ++i;
     }
 
-    for (; s != src->components.end(); s++) {
+    for (; s != src->components.end(); ++s) {
       stream << "super::";
     }
-    for (; d != dst->components.end(); d++) {
+    for (; d != dst->components.end(); ++d) {
       stream << MakeSnakeCase(*d) + "::";
     }
     return stream.str();
@@ -758,7 +758,7 @@ class RustGenerator : public BaseGenerator {
   //    the vtable, or
   // 3) return a hardcoded value because the vtable field value is set to zero.
   std::string TableBuilderArgsDefnType(const FieldDef &field,
-                                       const std::string lifetime) {
+                                       const std::string &lifetime) {
     const Type& type = field.value.type;
 
     switch (GetFullType(type)) {
@@ -786,7 +786,6 @@ class RustGenerator : public BaseGenerator {
         return typname;
       }
       case ftUnionValue: {
-        const auto typname = WrapInNameSpace(*type.enum_def);
         return "Option<flatbuffers::WIPOffset<flatbuffers::UnionWIPOffset>>";
       }
 
@@ -836,10 +835,11 @@ class RustGenerator : public BaseGenerator {
     return GetDefaultScalarValue(field);
   }
   std::string TableBuilderAddFuncDefaultValue(const FieldDef &field) {
+    // All branches of switch do the same action!
     switch (GetFullType(field.value.type)) {
       case ftUnionKey:
       case ftEnumKey: {
-        const std::string basetype = GetTypeBasic(field.value.type);
+        const std::string basetype = GetTypeBasic(field.value.type); //<- never used
         return GetDefaultScalarValue(field);
       }
 
@@ -848,7 +848,7 @@ class RustGenerator : public BaseGenerator {
   }
 
   std::string TableBuilderArgsAddFuncType(const FieldDef &field,
-                                          const std::string lifetime) {
+                                          const std::string &lifetime) {
     const Type& type = field.value.type;
 
     switch (GetFullType(field.value.type)) {
@@ -883,7 +883,6 @@ class RustGenerator : public BaseGenerator {
                ", " + typname + ">>";
       }
       case ftVectorOfUnionValue: {
-        const auto typname = WrapInNameSpace(*type.enum_def);
         return "flatbuffers::WIPOffset<flatbuffers::Vector<" + lifetime + \
                ", flatbuffers::ForwardsUOffset<flatbuffers::Table<" + \
                lifetime + ">>>";
@@ -916,7 +915,6 @@ class RustGenerator : public BaseGenerator {
         return typname;
       }
       case ftUnionValue: {
-        const auto typname = WrapInNameSpace(*type.enum_def);
         return "flatbuffers::WIPOffset<flatbuffers::UnionWIPOffset>";
       }
     }
@@ -970,7 +968,7 @@ class RustGenerator : public BaseGenerator {
   }
 
   std::string GenTableAccessorFuncReturnType(const FieldDef &field,
-                                             const std::string lifetime) {
+                                             const std::string &lifetime) {
     const Type& type = field.value.type;
 
     switch (GetFullType(field.value.type)) {
@@ -1041,8 +1039,8 @@ class RustGenerator : public BaseGenerator {
   }
 
   std::string GenTableAccessorFuncBody(const FieldDef &field,
-                                       const std::string lifetime,
-                                       const std::string offset_prefix) {
+                                       const std::string &lifetime,
+                                       const std::string &offset_prefix) {
     const std::string offset_name = offset_prefix + "::" + \
                                     GetFieldOffsetName(field);
     const Type& type = field.value.type;
@@ -1072,7 +1070,7 @@ class RustGenerator : public BaseGenerator {
       }
       case ftUnionKey:
       case ftEnumKey: {
-        const auto underlying_typname = GetTypeBasic(type);
+        const auto underlying_typname = GetTypeBasic(type); //<- never used
         const auto typname = WrapInNameSpace(*type.enum_def);
         const auto default_value = GetDefaultScalarValue(field);
         return "self._tab.get::<" + typname + ">(" + offset_name + \
@@ -1394,8 +1392,6 @@ class RustGenerator : public BaseGenerator {
         const bool is_scalar = IsScalar(field.value.type.base_type);
 
         std::string offset = GetFieldOffsetName(field);
-        std::string name = Name(field);
-        std::string value = GetDefaultScalarValue(field);
 
         // Generate functions to add data, which take one of two forms.
         //

src/idl_gen_text.cpp

@@ -309,10 +309,10 @@ bool GenerateTextFromTable(const Parser &parser, const void *table,
   if (struct_def == nullptr) {
     return false;
   }
-  auto text = *_text;
+  auto &text = *_text;
   text.reserve(1024);  // Reduce amount of inevitable reallocs.
   auto root = static_cast<const Table *>(table);
-  if (!GenStruct(*struct_def, root, 0, parser.opts, _text)) {
+  if (!GenStruct(*struct_def, root, 0, parser.opts, &text)) {
     return false;
   }
   text += NewLine(parser.opts);

src/idl_parser.cpp

@@ -2099,7 +2099,7 @@ Namespace *Parser::UniqueNamespace(Namespace *ns) {
   return ns;
 }
 
-std::string Parser::UnqualifiedName(std::string full_qualified_name) {
+std::string Parser::UnqualifiedName(const std::string &full_qualified_name) {
   Namespace *ns = new Namespace();
 
   std::size_t current, previous = 0;
@@ -3066,13 +3066,12 @@ bool StructDef::Deserialize(Parser &parser, const reflection::Object *object) {
   name = parser.UnqualifiedName(object->name()->str());
   predecl = false;
   sortbysize = attributes.Lookup("original_order") == nullptr && !fixed;
-  std::vector<uoffset_t> indexes =
-    std::vector<uoffset_t>(object->fields()->size());
-  for (uoffset_t i = 0; i < object->fields()->size(); i++)
-    indexes[object->fields()->Get(i)->id()] = i;
+  const auto& of = *(object->fields());
+  auto indexes = std::vector<uoffset_t>(of.size());
+  for (uoffset_t i = 0; i < of.size(); i++) indexes[of.Get(i)->id()] = i;
   size_t tmp_struct_size = 0;
   for (size_t i = 0; i < indexes.size(); i++) {
-    auto field = object->fields()->Get(indexes[i]);
+    auto field = of.Get(indexes[i]);
     auto field_def = new FieldDef();
     if (!field_def->Deserialize(parser, field) ||
         fields.Add(field_def->name, field_def)) {
@@ -3084,7 +3083,7 @@ bool StructDef::Deserialize(Parser &parser, const reflection::Object *object) {
       auto size = InlineSize(field_def->value.type);
       auto next_field =
           i + 1 < indexes.size()
-          ? object->fields()->Get(indexes[i+1])
+          ? of.Get(indexes[i+1])
           : nullptr;
       tmp_struct_size += size;
       field_def->padding =

src/util.cpp

@@ -127,12 +127,12 @@ static const char kPathSeparatorWindows = '\\';
 static const char *PathSeparatorSet = "\\/";  // Intentionally no ':'
 
 std::string StripExtension(const std::string &filepath) {
-  size_t i = filepath.find_last_of(".");
+  size_t i = filepath.find_last_of('.');
   return i != std::string::npos ? filepath.substr(0, i) : filepath;
 }
 
 std::string GetExtension(const std::string &filepath) {
-  size_t i = filepath.find_last_of(".");
+  size_t i = filepath.find_last_of('.');
   return i != std::string::npos ? filepath.substr(i + 1) : "";
 }