[Bug]: --descriptor_set_in input files should be joined by ; on Windows rather than : in ts_proto_library

[willjschmitt]

What happened?

Building a ts_proto_library with a proto library that has transitive dependencies fails to build with a "<entire-descriptor_set_in-arg>: No such file or directory" error

Inspecting the arguments provided to protoc, it looks like the paths are separated with : characters, which makes sense, since it's the typical construction on Linux, but it turns out the Windows protoc build wants to see them ;-separated. This is reinforced looking at some examples of how descriptor_set_in is joined in the protobuf repo: https://github.com/protocolbuffers/protobuf/blob/b9d1cfff8ca6814723889bade011f3fa4675d46d/protobuf.bzl#L294-L298 (other examples: https://github.com/search?q=repo%3Aprotocolbuffers%2Fprotobuf+--descriptor_set_in&type=code), where they string join on ctx.configuration.host_path_separator.

I don't see where the use of a system path separator for path delimiting is documented (the docs just say "delimited"), but the parsing by this character is defined here: https://github.com/protocolbuffers/protobuf/blob/b9d1cfff8ca6814723889bade011f3fa4675d46d/src/google/protobuf/compiler/command_line_interface.cc#L2134-L2157, with the path separator conditionally defined to : or ; at https://github.com/protocolbuffers/protobuf/blob/b9d1cfff8ca6814723889bade011f3fa4675d46d/src/google/protobuf/compiler/command_line_interface.cc#L950-L954

The only other use of this delimiter is in --proto_path, but I don't see any uses of --proto_path in this repo

Version

Development (host) and target OS/architectures: Windows 10

Output of bazel --version: 7.1.1

Version of the Aspect rules, or other relevant rules from your
WORKSPACE or MODULE.bazel file:

• rules_ts - 2.4.2 (patched with fix: convert forward slashes to backslashes for protoc plugins on Windows. #668)

Language(s) and/or frameworks involved:
Typescript, protobuf

How to reproduce

No response

Any other information?

No response