Protobuf imports not resolved outside of the current buffer's directory

[mcos]

I'm using flycheck as a syntax checker for protobuf files. Within an example protobuf file at path proto/path/to/foo.proto, I have the following import line:

import 'proto/other_path/to/bar.proto';

This import line gives the following error message:

Suspicious state from syntax checker protobuf-protoc: Flycheck checker protobuf-protoc returned non-zero exit code 1, but its output contained no errors: proto/other_path/to/bar.proto: File not found.
flycheck_foo.proto: Import "proto/other_path/to/bar.proto" was not found or had errors.

Try installing a more recent version of protobuf-protoc, and please open a bug report if the issue persists in the latest release.  Thanks!

I suspect that because the import file isn't present in the buffer's directory, the path isn't being included in the proto_path argument here:

flycheck/flycheck.el

Line 8606 in 1eecec8

(eval (concat "--proto_path=" (file-name-directory (buffer-file-name))))

Is it possible to configure flycheck to add extra --proto_path arguments to the compiler to help resolve this error?

Answers

• What you did, and what you expected to happen instead

I imported a protobuf file from outside the current buffer's directory and expected no syntax errors.

• Whether and how you were able to [reproduce the issue in emacs -Q][emacsQ]

Yes, the issue also arose in the same manner

• Your Flycheck setup from M-x flycheck-verify-setup

Syntax checkers for buffer foo.proto in protobuf-mode:

  protobuf-protoc
    - may enable: yes
    - predicate:  t
    - executable: Found at /usr/local/bin/protoc

Flycheck Mode is enabled.  Use C-u C-c ! x to enable disabled
checkers.

--------------------

Flycheck version: 32snapshot (package: 20180116.147)
Emacs version:    25.2.1
System:           x86_64-apple-darwin13.4.0
Window system:    ns

• Your operating system

MacOS 10.12.6

• Your Emacs version from M-x emacs-version

GNU Emacs 25.2.1 (x86_64-apple-darwin13.4.0, NS appkit-1265.21 Version 10.9.5 (Build 13F1911)) of 2017-04-21

• Your Flycheck version from M-x flycheck-version

Flycheck version: 32snapshot (package: 20180116.147)

[cpitclaudel]

Thanks, great report. Could you show what a valid command line invocation would look like?

There's a secondary issue here, which is that our patterns are incomplete. You shouldn't get a bad error like this (instead, you should get an error on line one complaining about the failed import).

[mcos]

Let me first link to the documentation around the --proto_path argument here: https://developers.google.com/protocol-buffers/docs/proto#importing-definitions

The protocol compiler searches for imported files in a set of directories specified on the protocol compiler command line using the -I/--proto_path flag. If no flag was given, it looks in the directory in which the compiler was invoked. In general you should set the --proto_path flag to the root of your project and use fully qualified names for all imports.

So based on this, from the above example, if I'm compiling proto/path/to/foo.proto, which imports proto/other_path/to/bar.proto. The conventional approach would be to invoke the protoc compiler in the parent of the proto/ directory, as follows:

protoc --proto_path=proto/ proto/path/to/foo.proto

Hope this helps. Happy to provide more info if needed.

[drielsma]

Our project has a pretty complex set of protobuf models that requires compilation with multiple -I arguments. This would be a huge win for us!

[cpitclaudel]

@drielsma Thanks for the feedback. I'm OK with adding support for a list of proto_path arguments. I also think the current one (passing the current directory) can be removed, right? Since the compiler runs from that directory.

Looping in @marsam (hi!) since he wrote the original checker.

@drielsma, would you like to write a patch? The new argument would work just like flycheck-rust-library-path, which should be a good source of inspiration.

[fishtreesugar]

It seems use uber/prototool's lint command could solve this issue

POC Impl

(flycheck-define-checker protobuf-prototool
  :command ("prototool" "lint"
            (eval (expand-file-name (buffer-file-name)))
            )
  :error-patterns
  ((error line-start (file-name) ":" line ":" column
          ":" (message) line-end))
  :modes protobuf-mode
  :predicate (lambda () (buffer-file-name)))