Code formatting check failure

Playbook ID: formatting-failure Category: build Severity: low Tags: formatting, prettier, black, gofmt, rustfmt, lint, style

What this failure means

A CI formatting check failed because one or more source files do not match the project's required code style as enforced by a formatter (Prettier, Black, gofmt, rustfmt, etc.). The check runs in verification mode and exits non-zero without modifying files.

Common log signals

Reformatting...
would reformat
files would be reformatted
not formatted
format check failed
run gofmt
run goimports
prettier.*check

Diagnosis

Most projects run a formatting check in --check mode in CI, which exits non-zero if any file would be changed. The underlying code is syntactically valid but does not conform to the configured style.

This commonly happens when:

• A developer's editor does not have format-on-save configured
• The developer used a different formatter version than CI
• Auto-generated code was committed without running the formatter
• A merge or rebase introduced formatting inconsistencies

Identify which files are affected:

# Prettier
npx prettier --check .

# Black (Python)
black --check .

# Go
gofmt -l .     # lists files that differ

# Rust
cargo fmt -- --check

Fix steps

1. Run the formatter in write mode locally to auto-fix all issues:

   # Prettier
   npx prettier --write .
   
   # Black
   black .
   
   # Go
   gofmt -w .
   goimports -w .
   
   # Rust
   cargo fmt
   
   # C/C++
   clang-format -i path/to/file.cpp
   

2. Stage and commit the formatting changes:

   git add -u
   git commit -m "style: apply formatter"
   

3. Ensure all team members have format-on-save configured in their editors, or install a pre-commit hook to format automatically:

   # Using pre-commit framework
   # .pre-commit-config.yaml
   repos:
     - repo: https://github.com/psf/black
       rev: 24.3.0
       hooks:
         - id: black
   

4. If the formatter version in CI differs from local, pin or align them:

   // package.json
   "prettier": "3.2.5"
   

   # pyproject.toml
   [tool.black]
   target-version = ['py311']
   

Validation

• Re-run the formatter in check mode and confirm it exits 0.
• Push the formatted commit and verify the CI formatting step passes.

Likely files to inspect

(Not specified.)

Run Faultline

faultline analyze build.log
faultline explain formatting-failure
faultline workflow build.log --json --mode agent

Search phrases this page answers

• Code formatting check failure
• Build: code formatting check failure
• Line longer than 100 characters
• GitHub Actions code formatting check failure
• faultline explain formatting-failure

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Generated from playbooks/bundled/log/build/formatting-failure.yaml. Do not edit directly — run make docs-generate.