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no-disabled-typecheck (BTTOOL001)

Added in 0.13.0 · Preview · Off by default (error)

Family: tooling · Standard: CES-58 · Languages: javascript, json, python, tsx, typescript

This rule is unstable and in preview. It runs only with preview = true, and only when it is selected.

Directive

No setting or directive turns off the type checker for a whole file, a whole project or a build. The rule reports:

Where Reported
TypeScript and JavaScript (.ts, .tsx, .js, next.config.*) a // @ts-nocheck or /* @ts-nocheck */ comment, and ignoreBuildErrors: true (the typescript option of next.config)
tsconfig.json, tsconfig.*.json, jsconfig.json "strict": false, and false for an option of the strict family: noImplicitAny, noImplicitThis, strictNullChecks, strictFunctionTypes, strictBindCallApply, strictPropertyInitialization, strictBuiltinIteratorReturn, useUnknownInCatchVariables, alwaysStrict
Python a # pyrefly: ignore-errors, # mypy: ignore-errors or # pyre-ignore-all-errors comment

A comment that silences one line (// @ts-expect-error, # pyrefly: ignore[<code>]) and # pyrefly: ignore-errors[<code>], which silences one kind of error, are left alone. An error by default.

Why

An agent whose build fails on types can make it pass by turning the checker off, and the errors stay in the code with nothing that reports them. Next.js documents ignoreBuildErrors as the way to "dangerously produce production code even when your application has errors". Since TypeScript 6.0 strict is true by default, so "strict": false is a choice someone wrote.

Do

// @ts-expect-error the types of the library return `any[]`; see its issue 812
const rows: Row[] = client.rows();

{ "compilerOptions": { "strict": true } }

Don't

// @ts-nocheck
const rows: Row[] = client.rows();

const config = { typescript: { ignoreBuildErrors: true } };

# pyrefly: ignore-errors

Suppression

In TypeScript and JavaScript, // botica: ignore[no-disabled-typecheck] on the line; in Python, # botica: ignore[no-disabled-typecheck] or # noqa: BTTOOL001 -- <reason>. JSON has no comments that botica reads: a tsconfig that has to keep an option off goes in the extend-ignores of [rules.no-disabled-typecheck].

A repository where the checker is off somewhere turns it back on in its own pull request: remove the directive or the setting, run the checker (pyrefly check, tsc --noEmit), and fix the errors or silence each on its line with the reason (# pyrefly: ignore[<code>], // @ts-expect-error <reason>). When the errors are too many for one pull request, keep the file in the extend-ignores of [rules.no-disabled-typecheck] and take it out file by file; a baseline file of pyrefly holds the existing errors and reports only new ones.

Discussion