Cannot override client version using bzlmod

[racosta]

The way the module extension is implemented doesn't actually allow you to override client versions because there will then be a name collision.

To reproduce, edit internal/test/bcr/MODULE.bazel. Notice, I haven't even tried to change versions yet, just re-use the defaults.

diff --git a/internal/test/bcr/MODULE.bazel b/internal/test/bcr/MODULE.bazel
index 0e2af0b..4938d37 100644
--- a/internal/test/bcr/MODULE.bazel
+++ b/internal/test/bcr/MODULE.bazel
@@ -9,5 +9,6 @@ local_path_override(
     path = "../../..",
 )
 openapi_gen = use_extension("@openapi_tools_generator_bazel//:extension.bzl", "openapi_gen")
+openapi_gen.client()
 use_repo(openapi_gen, "openapi_tools_generator_bazel_cli")

Then, from the internal/test/bcr directory: bazel build ... yields

❯ bazel build ...
ERROR: /home/user/.cache/bazel/_bazel_user/bd3dd79c0d936347dcd08a9f7a9427e7/external/bazel_tools/tools/build_defs/repo/jvm.bzl:306:24: Traceback (most recent call last):
        File "/home/user/.cache/bazel/_bazel_user/bd3dd79c0d936347dcd08a9f7a9427e7/external/openapi_tools_generator_bazel+/extension.bzl", line 7, column 38, in _openapi_generator_impl
                jvm_maven_import_external(
        File "/home/user/.cache/bazel/_bazel_user/bd3dd79c0d936347dcd08a9f7a9427e7/external/bazel_tools/tools/build_defs/repo/jvm.bzl", line 306, column 24, in jvm_maven_import_external
                jvm_import_external(
Error in repository_rule: A repo named openapi_tools_generator_bazel_cli is already generated by this module extension at /home/user/.cache/bazel/_bazel_user/bd3dd79c0d936347dcd08a9f7a9427e7/external/bazel_tools/tools/build_defs/repo/jvm.bzl:306:24
ERROR: Analysis of target '//:pylib' failed; build aborted: error evaluating module extension @@openapi_tools_generator_bazel+//:extension.bzl%openapi_gen
INFO: Elapsed time: 0.405s, Critical Path: 0.00s
INFO: 1 process: 1 internal.
ERROR: Build did NOT complete successfully

This is because this nested for loop is adding duplicated repos with the name openapi_tools_generator_bazel_cli. I'm not 100% sure how the resolution should be done. The names of the repos can either be adjusted to include the version (which would then require users to always specify the openapi_generator_cli attribute to the openapi_generator rule), or there can be some logic to decide which version should be used (max version?).

Temporarily we are resolving it by applying a patch which modifies the default value to what we need it to be, but I'd love to have this fixed properly. I can contribute, but I don't know the best practices for bazel module extensions well enough to know what the solution should be.

[BradHolmes]

Thank you for the report, and I would like to get this fixed before we release to the bazel central registry.

I'm not yet sure the best way to solve it. I got some feedback from bzlmod experts to consider either a toolchain or to somehow let users declare their own tool. I hope to work on that the next few days.

[BradHolmes]

I adopted the idea of a 2nd test of an older OpenAPI generator version in PR #64 -- can you see if that will work for you?