Referring to types from other namespaces in C++ now works correctly.

Previously, it would ignore the fact that the type comes from a
different namespace. Now they are pre-declared in their own namespace,
and referenced with a qualified name if necessary.

Bug: 16851682
Change-Id: I5cb625b86d28e7436b9e93c70a0fa16a600d9884
Tested: on Linux

include/flatbuffers/idl.h

@@ -159,6 +159,11 @@ template<typename T> class SymbolTable {
   std::vector<T *> vec;  // Used to iterate in order of insertion
 };
 
+// A name space, as set in the schema.
+struct Namespace {
+  std::vector<std::string> components;
+};
+
 // Base class for all definition types (fields, structs_, enums_).
 struct Definition {
   Definition() : generated(false) {}
@@ -183,7 +188,8 @@ struct StructDef : public Definition {
       predecl(true),
       sortbysize(true),
       minalign(1),
-      bytesize(0)
+      bytesize(0),
+      defined_namespace(nullptr)
     {}
 
   void PadLastField(size_t minalign) {
@@ -198,6 +204,7 @@ struct StructDef : public Definition {
   bool sortbysize;  // Whether fields come in the declaration or size order.
   size_t minalign;  // What the whole object needs to be aligned to.
   size_t bytesize;  // Size if fixed.
+  Namespace *defined_namespace;  // Where it was defined.
 };
 
 inline bool IsStruct(const Type &type) {
@@ -245,7 +252,16 @@ class Parser {
     root_struct_def(nullptr),
     source_(nullptr),
     cursor_(nullptr),
-    line_(1) {}
+    line_(1) {
+      // Just in case none are declared:
+      namespaces_.push_back(new Namespace());
+  }
+
+  ~Parser() {
+    for (auto it = namespaces_.begin(); it != namespaces_.end(); ++it) {
+      delete *it;
+    }
+  }
 
   // Parse the string containing either schema or JSON data, which will
   // populate the SymbolTable's or the FlatBufferBuilder above.
@@ -284,7 +300,7 @@ class Parser {
  public:
   SymbolTable<StructDef> structs_;
   SymbolTable<EnumDef> enums_;
-  std::vector<std::string> name_space_;  // As set in the schema.
+  std::vector<Namespace *> namespaces_;
   std::string error_;         // User readable error_ if Parse() == false
 
   FlatBufferBuilder builder_;  // any data contained in the file

src/idl_gen_go.cpp

@@ -585,24 +585,24 @@ static bool SaveType(const Parser &parser, const Definition &def,
                      bool needs_imports) {
   if (!classcode.length()) return true;
 
-  std::string name_space_name;
-  std::string name_space_dir = path;
-  for (auto it = parser.name_space_.begin();
-        it != parser.name_space_.end(); ++it) {
-    if (name_space_name.length()) {
-      name_space_name += ".";
-      name_space_dir += PATH_SEPARATOR;
+  std::string namespace_name;
+  std::string namespace_dir = path;
+  auto &namespaces = parser.namespaces_.back()->components;
+  for (auto it = namespaces.begin(); it != namespaces.end(); ++it) {
+    if (namespace_name.length()) {
+      namespace_name += ".";
+      namespace_dir += PATH_SEPARATOR;
     }
-    name_space_name = *it;
-    name_space_dir += *it;
-    mkdir(name_space_dir.c_str(), S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH);
+    namespace_name = *it;
+    namespace_dir += *it;
+    mkdir(namespace_dir.c_str(), S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH);
   }
 
 
   std::string code = "";
-  BeginFile(name_space_name, needs_imports, &code);
+  BeginFile(namespace_name, needs_imports, &code);
   code += classcode;
-  std::string filename = name_space_dir + PATH_SEPARATOR + def.name + ".go";
+  std::string filename = namespace_dir + PATH_SEPARATOR + def.name + ".go";
   return SaveFile(filename.c_str(), code, false);
 }
 

src/idl_gen_java.cpp

@@ -341,27 +341,27 @@ static bool SaveClass(const Parser &parser, const Definition &def,
                       bool needs_imports) {
   if (!classcode.length()) return true;
 
-  std::string name_space_java;
-  std::string name_space_dir = path;
-  for (auto it = parser.name_space_.begin();
-        it != parser.name_space_.end(); ++it) {
-    if (name_space_java.length()) {
-      name_space_java += ".";
-      name_space_dir += kPathSeparator;
+  std::string namespace_java;
+  std::string namespace_dir = path;
+  auto &namespaces = parser.namespaces_.back()->components;
+  for (auto it = namespaces.begin(); it != namespaces.end(); ++it) {
+    if (namespace_java.length()) {
+      namespace_java += ".";
+      namespace_dir += kPathSeparator;
     }
-    name_space_java += *it;
-    name_space_dir += *it;
-    mkdir(name_space_dir.c_str(), S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH);
+    namespace_java += *it;
+    namespace_dir += *it;
+    mkdir(namespace_dir.c_str(), S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH);
   }
 
   std::string code = "// automatically generated, do not modify\n\n";
-  code += "package " + name_space_java + ";\n\n";
+  code += "package " + namespace_java + ";\n\n";
   if (needs_imports) {
     code += "import java.nio.*;\nimport java.lang.*;\nimport java.util.*;\n";
     code += "import flatbuffers.*;\n\n";
   }
   code += classcode;
-  auto filename = name_space_dir + kPathSeparator + def.name + ".java";
+  auto filename = namespace_dir + kPathSeparator + def.name + ".java";
   return SaveFile(filename.c_str(), code, false);
 }
 

src/idl_parser.cpp

@@ -647,6 +647,7 @@ StructDef *Parser::LookupCreateStruct(const std::string &name) {
     structs_.Add(name, struct_def);
     struct_def->name = name;
     struct_def->predecl = true;
+    struct_def->defined_namespace = namespaces_.back();
   }
   return struct_def;
 }
@@ -838,9 +839,10 @@ bool Parser::Parse(const char *source, const char *filepath) {
     while (token_ != kTokenEof) {
       if (token_ == kTokenNameSpace) {
         Next();
-        name_space_.clear();
+        auto ns = new Namespace();
+        namespaces_.push_back(ns);
         for (;;) {
-          name_space_.push_back(attribute_);
+          ns->components.push_back(attribute_);
           Expect(kTokenIdentifier);
           if (!IsNext('.')) break;
         }

tests/include_test2.fbs

 include "include_test2.fbs";    // should be skipped
 
+namespace MyGame.OtherNameSpace;
+
 enum FromInclude:long { IncludeVal }
 
+struct Unused {}
+
+

tests/monster_test_generated.h

@@ -5,9 +5,19 @@
 
 #include "flatbuffers/flatbuffers.h"
 
+namespace MyGame {
+namespace OtherNameSpace {
+struct Unused;
+}  // namespace OtherNameSpace
+}  // namespace MyGame
+
 namespace MyGame {
 namespace Example {
 
+struct Test;
+struct Vec3;
+struct Monster;
+
 enum {
   Color_Red = 1,
   Color_Green = 2,
@@ -35,10 +45,6 @@ inline const char *EnumNameAny(int e) { return EnumNamesAny()[e]; }
 
 bool VerifyAny(const flatbuffers::Verifier &verifier, const void *union_obj, uint8_t type);
 
-struct Test;
-struct Vec3;
-struct Monster;
-
 MANUALLY_ALIGNED_STRUCT(2) Test {
  private:
   int16_t a_;