Error while compiling protocol buffer on mac - c++

Question

I am following the tutorial for protocol buffers and I keep running into different errors while compiling. my addressbook.proto file is in /Users/flexmaster411/protobuffer
protoc -I=/Users/flexmaster411/protobuffer --python_out= /Users/flexmaster411/protobuffer/addressbook.proto /Users/flexmaster411/protobuffer
I keep getting the following error even though I have syntax = "proto3" on my proto file
[libprotobuf WARNING google/protobuf/compiler/parser.cc:471] No syntax specified for the proto file. Please use 'syntax = "proto2";' or 'syntax = "proto3";' to specify a syntax version. (Defaulted to proto2 syntax.)
Not sure if I have correctly done the destination folders set up which is causing this or not Any help appreciated
syntax = "proto3";
package tutorial;
message Person {
string name = 1;
int32 id = 2; // Unique ID number for this person.
string email = 3;
enum PhoneType {
MOBILE = 0;
HOME = 1;
WORK = 2;
}
message PhoneNumber {
string number = 1;
PhoneType type = 2;
}
repeated PhoneNumber phones = 4;
}
// Our address book file is just one of these.
message AddressBook {
repeated Person people = 1;
}

Answer 1

It looks like you reversed the order of the parameters. /Users/flexmaster411/protobuffer is your output directory, so it should appear with --python_out. Since you specified it second, protoc thinks you're telling it that /Users/flexmaster411/protobuffer is an input. So it's trying to open a directory and then parse it as a .proto file. Amusingly, read() on a directory returns no data, which protoc interprets as a perfectly valid .proto file that simply doesn't declare anything! But it then gives you a warning because this empty file doesn't have any syntax line.
I think what you meant to type is:
protoc -I=/Users/flexmaster411/protobuffer --python_out=/Users/flexmaster411/protobuffer /Users/flexmaster411/protobuffer/addressbook.proto