Since last December, I’ve released five updates to expltools, a bundle that includes the static analysis tool explcheck for the expl3 programming language.

In v0.4.0 (January), I introduced the second processing step: lexical analysis. As noted in my previous blog post, this step converts the expl3 parts identified during preprocessing into TeX tokens, opening the door to deeper program analysis.

Throughout the rest of January, I focused on improving the lexical analysis and enhancing user experience. Notably, in v0.5.0, I added support for ignoring issues with inline TeX comments % noqa and the command-line option --ignored-issues. Furthermore, in v0.6.0 and v0.6.1, I implemented TOML config files to allow users to configure explcheck for their projects.

In v0.7.0 and v0.7.1 (February), I continued refining issue detection. To assist with validation, I added regression tests that regularly scan all expl3 files from TeX Live versions 2013 to 2023, comparing results to baselines as part of our continuous integration process.

Furthermore, in collaboration with Oliver Kopp and with the advice of Norbert Preining, we launched a public website that lists all issues in current TeX Live detected by explcheck.

This website offers an ongoing overview of explcheck results, enabling package maintainers to track issues without installing or running explcheck locally. It also helps me and other developers understand how explcheck behaves “in the wild,” beyond our curated unit tests. Using insights from this site, v0.7.0 and v0.7.1 include default configurations for many existing expl3 files, such as expl-code.tex, nicematrix.sty, and stex.sty, to improve detection outcomes.

Looking ahead to March, I plan to implement the next major processing steps in explcheck: syntactic analysis and semantic analysis. These steps will translate TeX tokens from the lexical analysis into higher-level statements—like variable declarations, function calls, and I/O operations—enabling more in-depth insights.

Beyond refining explcheck’s results, these improvements pave the way for more robust online resources, such as a comprehensive index of all expl3 symbols (functions, variables, constants, quarks, scan marks, etc.) in current TeX Live.

Stay tuned for further updates, and feel free to contribute or share feedback via the project repository.