---
name: julialang-external-deps
description: "Modify Julia's external dependencies and JLLs — patches under deps/patches/, version bumps in deps/, and JLL updates. Use when touching deps/ or any *_jll folder, including refreshing checksums."
license: "MIT"
metadata:
  decimalai-skill-id: "fe41e141-11d1-4137-ac80-7b96a9087540"
  decimalai-version-id: "619ffc02-73ac-401f-a325-20adc989c2ac"
  decimalai-version: "1"
  decimalai-body-sha256: "cf2cb2bdf089cfe8191e8a5d9e8a764b854d2cd868b3028f0772264ca8b120d2"
  decimalai-name: "julialang/external-deps"
  decimalai-format: "1"
  decimalai-invocation: "model"
  decimalai-category: "coding"
  decimalai-source: "https://app.decimal.ai/s/julialang-external-deps@1/SKILL.md"
---
# External dependencies & JLLs

Use this when modifying `deps/`, dependency patches, or a JLL.

## External dependencies (deps/, deps/patches/)

When modifying external dependencies (patches in `deps/patches/` or version
updates in `deps/`):

1. Always test builds with `USE_BINARYBUILDER=0` to ensure source builds work correctly.
2. For patches to external libraries:
   - Verify the patch applies cleanly by running the extraction and patch steps.
   - Test the full build of the dependency: `make -C deps USE_BINARYBUILDER=0 compile-<depname>`.
   - Prefer using the full upstream commit in `git am` format (e.g., `git format-patch`) which includes proper commit metadata.
3. When updating dependency versions, ensure all associated patches still apply.

## External JLLs

To update a JLL to the latest version:

- Update the version number in the appropriate jll folder.
- If the dependencies in the upstream jll changed, update the `Project.toml`.
- Run `make -f contrib/refresh_checksums.mk <jll>` to update the checksums. This may take a few minutes.