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feat(eslint-plugin): added related-getter-setter-pairs rule (#10192)
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* feat(eslint-plugin): added related-getter-setter-pairs rule

* Fixed stack popping

* Fixed stack popping

* Correction: reported getter always has return type annotation

* Correction: reported getter always has return type annotation

* Update packages/eslint-plugin/docs/rules/related-getter-setter-pairs.mdx

Co-authored-by: Joshua Chen <sidachen2003@gmail.com>

---------

Co-authored-by: Joshua Chen <sidachen2003@gmail.com>
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JoshuaKGoldberg and Josh-Cena authored Nov 11, 2024
1 parent 16fba0a commit 0409851
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61 changes: 61 additions & 0 deletions packages/eslint-plugin/docs/rules/related-getter-setter-pairs.mdx
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---
description: 'Enforce that `get()` types should be assignable to their equivalent `set()` type.'
---

import Tabs from '@theme/Tabs';
import TabItem from '@theme/TabItem';

> 🛑 This file is source code, not the primary documentation location! 🛑
>
> See **https://typescript-eslint.io/rules/related-getter-setter-pairs** for documentation.
TypeScript allows defining different types for a `get` parameter and its corresponding `set` return.
Prior to TypeScript 4.3, the types had to be identical.
From TypeScript 4.3 to 5.0, the `get` type had to be a subtype of the `set` type.
As of TypeScript 5.1, the types may be completely unrelated as long as there is an explicit type annotation.

Defining drastically different types for a `get` and `set` pair can be confusing.
It means that assigning a property to itself would not work:

```ts
// Assumes box.value's get() return is assignable to its set() parameter
box.value = box.value;
```

This rule reports cases where a `get()` and `set()` have the same name, but the `get()`'s type is not assignable to the `set()`'s.

## Examples

<Tabs>
<TabItem value="❌ Incorrect">

```ts
interface Box {
get value(): string;
set value(newValue: number);
}
```

</TabItem>
<TabItem value="✅ Correct">

```ts
interface Box {
get value(): string;
set value(newValue: string);
}
```

</TabItem>
</Tabs>

## When Not To Use It

If your project needs to model unusual relationships between data, such as older DOM types, this rule may not be useful for you.
You might consider using [ESLint disable comments](https://eslint.org/docs/latest/use/configure/rules#using-configuration-comments-1) for those specific situations instead of completely disabling this rule.

## Further Reading

- [MDN documentation on `get`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/get)
- [MDN documentation on `set`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/set)
- [TypeScript 5.1 Release Notes > Unrelated Types for Getters and Setters](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-5-1.html#unrelated-types-for-getters-and-setters)
1 change: 1 addition & 0 deletions packages/eslint-plugin/src/configs/all.ts
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Expand Up @@ -142,6 +142,7 @@ export = {
'@typescript-eslint/prefer-return-this-type': 'error',
'@typescript-eslint/prefer-string-starts-ends-with': 'error',
'@typescript-eslint/promise-function-async': 'error',
'@typescript-eslint/related-getter-setter-pairs': 'error',
'@typescript-eslint/require-array-sort-compare': 'error',
'require-await': 'off',
'@typescript-eslint/require-await': 'error',
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1 change: 1 addition & 0 deletions packages/eslint-plugin/src/configs/disable-type-checked.ts
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Expand Up @@ -56,6 +56,7 @@ export = {
'@typescript-eslint/prefer-return-this-type': 'off',
'@typescript-eslint/prefer-string-starts-ends-with': 'off',
'@typescript-eslint/promise-function-async': 'off',
'@typescript-eslint/related-getter-setter-pairs': 'off',
'@typescript-eslint/require-array-sort-compare': 'off',
'@typescript-eslint/require-await': 'off',
'@typescript-eslint/restrict-plus-operands': 'off',
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Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,7 @@ export = {
'@typescript-eslint/prefer-promise-reject-errors': 'error',
'@typescript-eslint/prefer-reduce-type-parameter': 'error',
'@typescript-eslint/prefer-return-this-type': 'error',
'@typescript-eslint/related-getter-setter-pairs': 'error',
'require-await': 'off',
'@typescript-eslint/require-await': 'error',
'@typescript-eslint/restrict-plus-operands': [
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3 changes: 2 additions & 1 deletion packages/eslint-plugin/src/configs/strict-type-checked.ts
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Expand Up @@ -76,6 +76,7 @@ export = {
'@typescript-eslint/prefer-promise-reject-errors': 'error',
'@typescript-eslint/prefer-reduce-type-parameter': 'error',
'@typescript-eslint/prefer-return-this-type': 'error',
'@typescript-eslint/related-getter-setter-pairs': 'error',
'require-await': 'off',
'@typescript-eslint/require-await': 'error',
'@typescript-eslint/restrict-plus-operands': [
Expand All @@ -93,10 +94,10 @@ export = {
{
allowAny: false,
allowBoolean: false,
allowNever: false,
allowNullish: false,
allowNumber: false,
allowRegExp: false,
allowNever: false,
},
],
'no-return-await': 'off',
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2 changes: 2 additions & 0 deletions packages/eslint-plugin/src/rules/index.ts
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Expand Up @@ -114,6 +114,7 @@ import preferReturnThisType from './prefer-return-this-type';
import preferStringStartsEndsWith from './prefer-string-starts-ends-with';
import preferTsExpectError from './prefer-ts-expect-error';
import promiseFunctionAsync from './promise-function-async';
import relatedGetterSetterPairs from './related-getter-setter-pairs';
import requireArraySortCompare from './require-array-sort-compare';
import requireAwait from './require-await';
import restrictPlusOperands from './restrict-plus-operands';
Expand Down Expand Up @@ -244,6 +245,7 @@ const rules = {
'prefer-string-starts-ends-with': preferStringStartsEndsWith,
'prefer-ts-expect-error': preferTsExpectError,
'promise-function-async': promiseFunctionAsync,
'related-getter-setter-pairs': relatedGetterSetterPairs,
'require-array-sort-compare': requireArraySortCompare,
'require-await': requireAwait,
'restrict-plus-operands': restrictPlusOperands,
Expand Down
113 changes: 113 additions & 0 deletions packages/eslint-plugin/src/rules/related-getter-setter-pairs.ts
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import type { TSESTree } from '@typescript-eslint/utils';

import { AST_NODE_TYPES } from '@typescript-eslint/utils';

import { createRule, getNameFromMember, getParserServices } from '../util';

type Method = TSESTree.MethodDefinition | TSESTree.TSMethodSignature;

type GetMethod = {
kind: 'get';
returnType: TSESTree.TSTypeAnnotation;
} & Method;

type GetMethodRaw = {
returnType: TSESTree.TSTypeAnnotation | undefined;
} & GetMethod;

type SetMethod = { kind: 'set'; params: [TSESTree.Node] } & Method;

interface MethodPair {
get?: GetMethod;
set?: SetMethod;
}

export default createRule({
name: 'related-getter-setter-pairs',
meta: {
type: 'problem',
docs: {
description:
'Enforce that `get()` types should be assignable to their equivalent `set()` type',
recommended: 'strict',
requiresTypeChecking: true,
},
messages: {
mismatch:
'`get()` type should be assignable to its equivalent `set()` type.',
},
schema: [],
},
defaultOptions: [],
create(context) {
const services = getParserServices(context);
const checker = services.program.getTypeChecker();
const methodPairsStack: Map<string, MethodPair>[] = [];

function addPropertyNode(
member: GetMethod | SetMethod,
inner: TSESTree.Node,
kind: 'get' | 'set',
): void {
const methodPairs = methodPairsStack[methodPairsStack.length - 1];
const { name } = getNameFromMember(member, context.sourceCode);

methodPairs.set(name, {
...methodPairs.get(name),
[kind]: inner,
});
}

return {
':matches(ClassBody, TSInterfaceBody, TSTypeLiteral):exit'(): void {
const methodPairs = methodPairsStack[methodPairsStack.length - 1];

for (const pair of methodPairs.values()) {
if (!pair.get || !pair.set) {
continue;
}

const getter = pair.get;

const getType = services.getTypeAtLocation(getter);
const setType = services.getTypeAtLocation(pair.set.params[0]);

if (!checker.isTypeAssignableTo(getType, setType)) {
context.report({
node: getter.returnType.typeAnnotation,
messageId: 'mismatch',
});
}
}

methodPairsStack.pop();
},
':matches(MethodDefinition, TSMethodSignature)[kind=get]'(
node: GetMethodRaw,
): void {
const getter = getMethodFromNode(node);

if (getter.returnType) {
addPropertyNode(node, getter, 'get');
}
},
':matches(MethodDefinition, TSMethodSignature)[kind=set]'(
node: SetMethod,
): void {
const setter = getMethodFromNode(node);

if (setter.params.length === 1) {
addPropertyNode(node, setter, 'set');
}
},

'ClassBody, TSInterfaceBody, TSTypeLiteral'(): void {
methodPairsStack.push(new Map());
},
};
},
});

function getMethodFromNode(node: GetMethodRaw | SetMethod) {
return node.type === AST_NODE_TYPES.TSMethodSignature ? node : node.value;
}

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