Coming from mypy or pyright

This guide helps you migrate a project from mypy or pyright to ty.

Migration tips

mypy disables an error code with # type: ignore[code]; pyright suppresses a single line with # pyright: ignore[reportXyz]; ty's equivalent is # ty: ignore[rule]. See this page for more information about suppression comments.
mypy's disable_error_code and pyright's reportXyz = "none" both correspond to setting <rule> = "ignore" under [tool.ty.rules]. See this section for details.
Severities in ty are ignore, warn, error. Pyright's "information" and "hint" levels have no direct ty equivalent — use warn for both.
If you are looking for the equivalent of disallow_untyped_defs / no-untyped-def (mypy) or reportMissingParameterType, reportUnknownParameterType (pyright), check out this FAQ entry.

How to read this table

ty rule: the canonical name, as listed in Rules. Configure under [tool.ty.rules].
mypy error code: the value passed to # type: ignore[<code>] or disable_error_code. Some ty rules surface as one of mypy's catch-all codes (misc, assignment, valid-type); these mappings are deliberately broad.
pyright diagnostic: the report* setting in pyrightconfig.json or [tool.pyright].

A blank cell means no direct equivalent exists in that checker (the diagnostic is either not emitted, or is folded into a broader category that already appears for another ty rule).

Mapping table

ty rule	mypy error code	pyright diagnostic
`call-abstract-method`		`reportAbstractUsage`
`call-non-callable`	`operator`	`reportCallIssue`
`conflicting-declarations`	`no-redef`	`reportRedeclaration`
`conflicting-metaclass`	`metaclass`	`reportGeneralTypeIssues`
`cyclic-class-definition`	`misc`	`reportGeneralTypeIssues`
`deprecated`	`deprecated`	`reportDeprecated`
`division-by-zero`
`duplicate-base`	`misc`	`reportGeneralTypeIssues`
`empty-body`	`empty-body`
`inconsistent-mro`	`misc`	`reportGeneralTypeIssues`
`index-out-of-bounds`	`misc`	`reportGeneralTypeIssues`
`invalid-argument-type`	`arg-type` `index` `type-var` `typeddict-item`	`reportArgumentType` `reportAssignmentType`
`invalid-assignment`	`assignment`	`reportAssignmentType`
`invalid-attribute-access`	`misc`	`reportAttributeAccessIssue`
`invalid-await`	`misc`	`reportGeneralTypeIssues`
`invalid-base`	`valid-type`	`reportGeneralTypeIssues`
`invalid-context-manager`	`misc` `attr-defined`	`reportGeneralTypeIssues`
`invalid-exception-caught`	`misc`	`reportGeneralTypeIssues`
`invalid-key`	`typeddict-item` `typeddict-unknown-key`	`reportAssignmentType`
`invalid-metaclass`	`metaclass`
`invalid-method-override`	`override`	`reportIncompatibleMethodOverride`
`invalid-overload`	`no-overload-impl`	`reportNoOverloadImplementation`
`invalid-parameter-default`	`assignment`	`reportArgumentType`
`invalid-raise`	`misc`	`reportGeneralTypeIssues`
`invalid-return-type`	`return-value`	`reportReturnType`
`invalid-type-arguments`	`misc` `type-var`	`reportInvalidTypeArguments`
`invalid-type-form`	`valid-type`	`reportInvalidTypeForm`
`missing-argument`	`call-arg`	`reportCallIssue`
`missing-override-decorator`	`explicit-override`	`reportImplicitOverride`
`missing-typed-dict-key`	`typeddict-item`	`reportAssignmentType`
`no-matching-overload`	`call-overload`	`reportCallIssue`
`not-iterable`	`misc` `attr-defined`	`reportGeneralTypeIssues`
`not-subscriptable`	`index`	`reportIndexIssue`
`parameter-already-assigned`	`misc` `call-arg`	`reportCallIssue`
`possibly-missing-attribute`	`union-attr`	`reportOptionalMemberAccess` `reportAttributeAccessIssue`
`possibly-unresolved-reference`	`possibly-undefined`	`reportPossiblyUnboundVariable`
`redundant-cast`	`redundant-cast`	`reportUnnecessaryCast`
`too-many-positional-arguments`	`call-arg`	`reportCallIssue`
`type-assertion-failure`	`assert-type`	`reportAssertTypeFailure`
`undefined-reveal`	`unimported-reveal`
`unknown-argument`	`call-arg`	`reportCallIssue`
`unresolved-attribute`	`attr-defined`	`reportAttributeAccessIssue`
`unresolved-import`	`import-not-found`	`reportMissingImports`
`unresolved-reference`	`name-defined`	`reportUndefinedVariable`
`unsupported-operator`	`operator`	`reportOperatorIssue`
`unused-awaitable`	`unused-coroutine` `unused-awaitable`	`reportUnusedCoroutine`
`unused-ignore-comment`	`unused-ignore`	`reportUnnecessaryTypeIgnoreComment`

The full list of ty rules — including those without a direct equivalent above — is in Rules. Contributions to extend this mapping are welcome via pull request to the ty repository; see issue #2111 for context.