Linting

Run acton check to catch compiler errors and lint diagnostics in Tolk contracts, tests, and standalone scripts. Command supports automatic fixes and various output formats for use on CI platforms, such as GitHub and GitLab.

Lint the whole project

Run:

acton check

This checks all lint roots discovered from the project:

• Contracts declared in Acton.toml;
• Workspace *.test.tolk files;
• Standalone script roots that define main().

Use this command before commits and before CI runs.

Lint one contract or one file

Use a contract name from Acton.toml:

acton check Counter

Use a file path to check one source file:

acton check ./contracts/Counter.tolk

Prefer an explicit path such as ./contracts/Counter.tolk when a file name could be mistaken for a contract name from Acton.toml.

Apply automatic fixes

Apply safe fixes in place:

acton check --fix

--fix works only with the default plain terminal output. It applies only fixes that the linter marks as automatically applicable, and the command can still exit with a non-zero status if unfixed diagnostics remain.

Focus on specific rules

Explain a diagnostic code:

acton check --explain E002

Run only selected rules during one pass:

acton check --enable-only E003,E028

Use full rule codes for predictable matching.

Set project lint policy

Store the default lint policy in Acton.toml:

[lint]
max-warnings = 0
exclude = ["contracts/generated/*.tolk"]
output-format = "sarif"

[lint.rules]
unused-variable = "deny"
mutable-variable-can-be-immutable = "warn"

[lint.rules.Counter]
unused-variable = "allow"

Use:

• [lint] for global behavior such as warning thresholds, excluded paths, and default output format;
• [lint.rules] for project-wide rule levels;
• [lint.rules.<ContractName>] for per-contract overrides.

Supported rule levels are:

• allow to disable the rule;
• warn to report the rule as a warning;
• deny to report the rule as an error.

Keep these exclude rules in mind:

• In project-wide runs, excluded contracts are skipped as lint roots.
• If an explicit target is passed, that contract or file is still checked.
• Excluded dependency files can still be parsed for imports and types, but their lint diagnostics are hidden.
• Excluded roots do not report compiler errors or lint diagnostics in project-wide runs.
• Exclude matching works against both project-root-relative and absolute paths.

When only one line needs an exception, suppress the rule on the next line instead of weakening the whole project policy:

// check-disable-next-line unused-variable
val legacy = oldLogic();

Another common pattern is suppressing more than one diagnostic:

// check-disable-next-line unused-variable, write-only-variable
var tmp = 10;
tmp = 20;

Use rule names such as unused-variable or deprecated-symbol-use, not diagnostic codes such as E002 or E004, in suppression comments.

For suppressions:

• The comment applies only to the immediately following line.
• The comment must use // and sit directly above the target line.
• all suppresses all diagnostics for the next line.
• Unknown rule names in the suppression list are ignored.
• compiler-error rule (C001) and parse-error rule cannot be suppressed.

Use linting in CI

Fail the job on any warning:

[lint]
max-warnings = 0

Then run:

acton check # plain terminal output

For machine-readable reports, choose a non-plain output format:

acton check --output-format json
acton check --output-format sarif --output-file build/reports/lint.sarif
acton check --output-format github
acton check --output-format gitlab --output-file gl-code-quality-report.json

--fix can only be used with plain output. With json, sarif, github, or gitlab, Acton rejects the command instead of rewriting files.

Refer to the CI integration page for more information on output formats and overall CI setup.

See also

• acton check reference
• Lint rules reference