proto_library's import_prefix does not work across repository boundaries

[RNabel]

Description of the problem / feature request:

import_prefix does not set the prefix correctly when the proto_library target lives in an external dependency.

Feature requests: what underlying problem are you trying to solve with this feature?

The import_prefix should work across repo boundaries.

Bugs: what's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

(Skip to Repro case below for a zip containing a testable example of the reported behaviour)

Create a proto_library with import_prefix and reference it from a different workspace. If the depended-on repository has name dependency_a and the depended-on proto_library target uses import_prefix = "prefix_a", the expected import path is in a .proto file is:

import "prefix_a/test.proto";

but the actual path is:

import "prefix_a/external/dependency_a/test.proto";

Repro case

Please download this repro.zip, which illustrates this behaviour using a local_repository.

$ tree
.
├── BUILD
├── WORKSPACE
├── local_repo
│   ├── BUILD
│   ├── WORKSPACE
│   └── imported.proto
└── test.proto

Build the repro target: bazel build :test_proto
The file test.proto contains both the expected, non-functional import path, and the actual import path.

What operating system are you running Bazel on?

macOS 10.14

What's the output of bazel info release?

Tested on both 0.22 and 0.24.1

Have you found anything relevant by searching the web?

Related error: proto_source_root not working across multiple workspaces #4665

[aiuto]

My bad on the mis-categorization

[hlopko]

Hi Robin, could you pls check that #8683 fixes your problem?