Use swig from BCR, allowing to remove last dep on WORKSPACE

[hzeller]

No description provided.

[hzeller]

CC: @oharboe

[gemini-code-assist]

Code Review

This pull request migrates the swig dependency from a WORKSPACE definition to using the version from the Bazel Central Registry (BCR). This is a great improvement for modernizing the build and removing the legacy WORKSPACE file. The changes in the .bzl files to update the swig label are correct. I've only left one comment in MODULE.bazel regarding the alphabetical sorting of dependencies to improve maintainability.

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[oharboe]

😌

[hzeller]

It is unclear why the CI failed - there are no usable logs.

[hzeller]

making this a draft for now. Looks like the other CI shows an actual error that can be traced to swig

https://jenkins.openroad.tools/job/OpenROAD-Public/job/PR-9555-merge/1/pipeline-overview/?start-byte=34095&selected-node=161#log-161-138

[maliberty]

[2026-02-26T17:18:41.705Z] (17:18:41) ERROR: /tmp/workspace/OpenROAD-Public_PR-9555-head-1-bazel-ci/src/ant/BUILD:75:12: Action src/ant/swig.cc [for tool] failed: (Exit 1): swig failed: error executing Action command (from target //src/ant:swig) bazel-out/k8-opt-exec-ST-d57f47055a04/bin/external/swig+/swig -tcl8 -c++ -module ant -namespace -prefix ant -Isrc/ant/src -o bazel-out/k8-opt-exec-ST-d57f47055a04/bin/src/ant/swig.cc ... (remaining 1 argument skipped)
[2026-02-26T17:18:41.705Z]
[2026-02-26T17:18:41.705Z] Use --sandbox_debug to see verbose messages from the sandbox and retain the sandbox build root for debugging
[2026-02-26T17:18:41.705Z] :EOF: Error: Unable to find 'swig.swg'
[2026-02-26T17:18:41.705Z] :2: Error: Unable to find 'tcl8.swg'

[hzeller]

Looks like the BCR version is doing things a bit differently. Will have to dig into that and possibly upstream a fix.
So this PR might take a little longer.

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[hzeller]

Added swig 4.3.0.bcr.2 with tcl support in in bazelbuild/bazel-central-registry#7732 so this should work now.

Note, even though we could remove WORKSPACE in this PR (yay!), we can't remove the common --enable_workspace quite yet; apparently this requires the rules_python transition from #9558 first which currently awaits yaml-issue-resolving.

[hzeller]

Ready for review.

[maliberty]

🥇