Unexpected error when formatting valid proto definition

[johanbrandhorst]

The following protofile produces a pretty hard-to-debug error when linting (and probably for other stuff as well):

syntax = "proto3";

import "google/api/annotations.proto";

service Test {
    rpc Test(Void) returns (Void) {
        option (google.api.http) = {
            post: "/api/v1/test";
            body: "*";
        };
    }
}

message Void {}

The error:

$ prototool lint test.proto
test.proto:12:1: found "}" but expected [.proto element {comment|option|import|syntax|enum|service|package|message}]

Specifically, it's the semicolons inside the options object that the parser doesn't like.

This is, of course, a perfectly valid protofile definition (as protoc accepts it), though I admit I'm having trouble finding a definition for multi-value options. See https://developers.google.com/protocol-buffers/docs/reference/proto3-spec#option, https://developers.google.com/protocol-buffers/docs/proto#customoptions for more information. The latter lists a single example of a multi-value option where all options are on the same line, without semicolon;

// usage:
message Bar {
  optional int32 a = 1 [(foo_options).opt1 = 123, (foo_options).opt2 = "baz"];
  // alternative aggregate syntax (uses TextFormat):
  optional int32 b = 2 [(foo_options) = { opt1: 123 opt2: "baz" }];
}

So perhaps this could be a linter option? In any case the parser should allow it.

[bufdev]

This is an issue in emicklei/proto, see #1, we will need to file an issue over there.

[johanbrandhorst]

In fact, even when fixing this (removing the semicolons) and then running prototool format -w twice, the second run fails because the parser can't parse the output of prototool format when using nested options:

1. Start with a protofile with nested options:

syntax = "proto3";

import "google/api/annotations.proto";

service Test {
    rpc Test(Void) returns (Void) {
        option (google.api.http) = {
            get: "/api/v1/test"
            additional_bindings {
                post: "/api/v1/test"
                body: "*"
            }
        };
    }
}

message Void {}

2. Run prototool format -w twice:

$ prototool format -w
$ prototool format -w
test.proto:7:44:1:1:Error while parsing option value for "http": Expected "{", found ".".

The formatted file looks like this:

syntax = "proto3";

import "google/api/annotations.proto";

service Test {
	rpc Test(Void) returns (Void) {
		option (google.api.http) = {
			get: "/api/v1/test"
			additional_bindings.post: "/api/v1/test"
			additional_bindings.body: "*"
		};
	}
}

message Void {}

[johanbrandhorst]

I could raise a separate issue for this case if you wish?

[bufdev]

I’d prefer the relevant issues be filed in emicklei/proto, no need to create new issues here. A test case in a PR to reproduce the above would be good too.

[johanbrandhorst]

Raised emicklei/proto#79 and emicklei/proto#80, I also raised #27 so we can make a decision on what should be done for that case. Closing this.