Add more warnings to for the ObjC runtime build

Working on https://github.com/google/protobuf/issues/1599, specifically:
- Turn on more warnings that the Xcode UI calls out with individual controls.
- Manually add:
  -Wundef
  -Wswitch-enum
- Manually add and then diable in the unittests because of XCTest's headers:
  -Wreserved-id-macro
  -Wdocumentation-unknown-command
- Manually add -Wdirect-ivar-access, but disable it for the unittests and in
  the library code (via #pragmas to suppress it). This is done so proto users
  can enable the warning.

3 files changed, 45 insertions, 2 deletions

diff --git a/src/google/protobuf/compiler/objectivec/objectivec_file.cc b/src/google/protobuf/compiler/objectivec/objectivec_file.cc
index ccf5fbb4..7774058e 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_file.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_file.cc
@@ -182,6 +182,10 @@ void FileGenerator::GenerateHeader(io::Printer *printer) {
     import_writer.Print(printer);
   }
 
+  // Note:
+  //  deprecated-declarations suppression is only needed if some place in this
+  //    proto file is something deprecated or if it references something from
+  //    another file that is deprecated.
   printer->Print(
       "// @@protoc_insertion_point(imports)\n"
       "\n"
@@ -292,14 +296,34 @@ void FileGenerator::GenerateSource(io::Printer *printer) {
     import_writer.Print(printer);
   }
 
+  bool includes_oneof = false;
+  for (vector<MessageGenerator *>::iterator iter = message_generators_.begin();
+       iter != message_generators_.end(); ++iter) {
+    if ((*iter)->IncludesOneOfDefinition()) {
+      includes_oneof = true;
+      break;
+    }
+  }
+
+  // Note:
+  //  deprecated-declarations suppression is only needed if some place in this
+  //    proto file is something deprecated or if it references something from
+  //    another file that is deprecated.
   printer->Print(
       "// @@protoc_insertion_point(imports)\n"
       "\n"
       "#pragma clang diagnostic push\n"
-      "#pragma clang diagnostic ignored \"-Wdeprecated-declarations\"\n"
-      "\n");
+      "#pragma clang diagnostic ignored \"-Wdeprecated-declarations\"\n");
+  if (includes_oneof) {
+    // The generated code for oneof's uses direct ivar access, suppress the
+    // warning incase developer turn that on in the context they compile the
+    // generated code.
+    printer->Print(
+        "#pragma clang diagnostic ignored \"-Wdirect-ivar-access\"\n");
+  }
 
   printer->Print(
+      "\n"
       "#pragma mark - $root_class_name$\n"
       "\n"
       "@implementation $root_class_name$\n\n",
diff --git a/src/google/protobuf/compiler/objectivec/objectivec_message.cc b/src/google/protobuf/compiler/objectivec/objectivec_message.cc
index bf272596..e1a78619 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_message.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_message.cc
@@ -246,6 +246,22 @@ void MessageGenerator::DetermineForwardDeclarations(set<string>* fwd_decls) {
   }
 }
 
+bool MessageGenerator::IncludesOneOfDefinition() const {
+  if (!oneof_generators_.empty()) {
+    return true;
+  }
+
+  for (vector<MessageGenerator*>::const_iterator iter =
+           nested_message_generators_.begin();
+       iter != nested_message_generators_.end(); ++iter) {
+    if ((*iter)->IncludesOneOfDefinition()) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
 void MessageGenerator::GenerateEnumHeader(io::Printer* printer) {
   for (vector<EnumGenerator*>::iterator iter = enum_generators_.begin();
        iter != enum_generators_.end(); ++iter) {
diff --git a/src/google/protobuf/compiler/objectivec/objectivec_message.h b/src/google/protobuf/compiler/objectivec/objectivec_message.h
index 8565e76f..910535ac 100644
--- a/src/google/protobuf/compiler/objectivec/objectivec_message.h
+++ b/src/google/protobuf/compiler/objectivec/objectivec_message.h
@@ -66,6 +66,9 @@ class MessageGenerator {
   void GenerateExtensionRegistrationSource(io::Printer* printer);
   void DetermineForwardDeclarations(set<string>* fwd_decls);
 
+  // Checks if the message or a nested message includes a oneof definition.
+  bool IncludesOneOfDefinition() const;
+
  private:
   void GenerateParseFromMethodsHeader(io::Printer* printer);