fantomas
Reporting a bug
Fantomas should never break your code. When it does, when it throws, or when formatting its own result changes it again, we would like to hear about it.
The online tool
We prefer bugs to be reported through the online tool. Paste the code, pick the settings you use, and press Looks wrong? Create an issue!. It formats with the latest main branch and opens a GitHub issue with everything a maintainer needs to reproduce it.
Keep the code as small as you can. Isolate the part that goes wrong: a report of five lines gets fixed much sooner than a file of five hundred. It also has to fit in a link, and GitHub refuses a link to a new issue once it grows past a few thousand characters.
Not sure which settings apply to a file? dotnet fantomas doctor <file> lists every setting your
.editorconfig sets for it, see Diagnosing one file.
Please report a new issue even when one looks the same. Bugs that look alike often have different causes, and the maintainers can tell.
With a coding agent
If you work with a coding agent, the fantomas-report skill does the same, starting from the file
Fantomas failed on:
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Then ask your agent to report the file Fantomas could not format. The skill:
- shrinks the code to a minimal sample, and notes which variations make a difference;
- tries it against released versions, to tell a regression from an old bug, and a bug that is already fixed from one that is not;
- recognizes code Fantomas cannot format by design, such as the nesting that depends on a define, and proposes a change to your code instead;
- checks the sample against the latest main branch, the same way the online tool does;
- opens the new issue form in your browser, filled in the way the online tool fills it.
It never submits the issue: you read it and decide. It needs the .NET 10 SDK, and Bun or Node.js 22.18 or later. It asks before it clones the Fantomas repository, which makes shrinking a sample much faster.