[tdf-discuss] Migrating LibreOffice Build System to Bazel

Dear LibreOffice developers and contributors,

I recently opened Bug 
168776(https://bugs.documentfoundation.org/show_bug.cgi?id=168776) to 
propose migrating the LibreOffice build system from Make, autotools, and 
Perl to *Bazel*.
In the discussion there, I was advised to bring this topic to this 
mailing list for broader feedback and discussion.

I believe such a migration could bring several benefits and 
simplifications, including:

 *

   *Incremental Builds:* Bazel can significantly reduce compilation
   time compared to the current Make-based system.

 *

   *Simplified File Structure:* As of October 2025, LibreOffice
   contains about 2,581 Makefiles. This could be reduced to around 150
   |BUILD.bazel| files (roughly one per module).

 *

   *Unified Testing:* |bazel test| would remove the need for separate
   Makefiles for unit tests.

 *

   *Modern Build Language:* Legacy Perl scripts could be replaced by
   the modern, Python-like Starlark language.

 *

   *Refactoring Opportunity:* The current integration among autotools,
   gbuild, and Perl scripts makes refactoring legacy OpenOffice-era
   code difficult.

 *

   *Module Management:* Bazel’s |MODULE.bazel| and |http_archive|
   features can consolidate external dependencies into a single
   configuration file, rather than the scattered |external/| directory.

 *

   *Cross-Platform Builds:* |select()| expressions can cleanly handle
   platform-specific build options.

I understand that such a migration would involve a significant 
transition period and changes to the CI infrastructure.
However, as LibreOffice continues to grow in complexity and scale, 
modernizing the build system could improve maintainability, 
reproducibility, and the onboarding experience for new developers.

In short, Bazel could modernize LibreOffice’s build process, reduce 
maintenance burden, and improve reproducibility.
I’d like to ask whether there have been any previous attempts or 
internal discussions on this topic, and whether a *partial or per-module 
migration* could be considered as a starting point.

Thank you for your time and consideration.

Best regards,
Haruhiko Nishizaki

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