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feat(eslint-plugin): [no-misused-disposable] add rule (PROTOTYPE) #11087

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feat(eslint-plugin): [no-misused-disposable] add rule (PROTOTYPE) #11087

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126 changes: 126 additions & 0 deletions packages/eslint-plugin/src/rules/no-misused-disposable.ts
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import type { TSESTree } from '@typescript-eslint/utils';

import { AST_NODE_TYPES } from '@typescript-eslint/utils';
import { nullThrows } from '@typescript-eslint/utils/eslint-utils';
import * as tsutils from 'ts-api-utils';

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

export default createRule({
name: 'no-misused-disposable',
meta: {
type: 'suggestion',
docs: {
description: "Disallow using disposables in ways that won't be disposed",
},
messages: {
misusedDisposable:
"Disposable is not handled correctly. Disposable must be in a 'using'/'await using' declaration, or returned",
},
schema: [],
},
defaultOptions: [],
create(context) {
const services = getParserServices(context);
const checker = services.program.getTypeChecker();
return {
CallExpression(node): void {
const type = services.getTypeAtLocation(node);
const disposeSymbol = tsutils.getWellKnownSymbolPropertyOfType(
type,
'dispose',
checker,
);
if (disposeSymbol == null) {
return;
}

if (isValidWayToHandleDisposable(node)) {
return;
}
context.report({
node,
messageId: 'misusedDisposable',
});
},
};

function traverseUpTransparentParents(node: TSESTree.Node): TSESTree.Node {
if (node.parent == null) {
return node;
}
switch (node.parent.type) {
case AST_NODE_TYPES.ConditionalExpression:
return traverseUpTransparentParents(node.parent);
case AST_NODE_TYPES.LogicalExpression:
if (node.parent.operator === '||' || node.parent.operator === '&&') {
return traverseUpTransparentParents(node.parent);
}
return node;
case AST_NODE_TYPES.SequenceExpression:
if (node.parent.expressions.at(-1) === node) {
return traverseUpTransparentParents(node.parent);
}
return node;
default:
return node;
}
}

function isValidWayToHandleDisposable(
disposableNode: TSESTree.Node,
): boolean {
disposableNode = traverseUpTransparentParents(disposableNode);

if (disposableNode.parent == null) {
return false;
}

if (disposableNode.parent.type === AST_NODE_TYPES.VariableDeclarator) {
// using x = makeDisposable();
if (
['using', 'await using'].includes(disposableNode.parent.parent.kind)
) {
return true;
}

// Support code like:
// const foo = makeDisposable();
// return foo;
if (
disposableNode.parent.parent.kind === 'const' &&
disposableNode.parent.id.type === AST_NODE_TYPES.Identifier
) {
const scope = context.sourceCode.getScope(disposableNode);
const smVariable = nullThrows(
findVariable(scope, disposableNode.parent.id),
"couldn't find variable",
);
for (const reference of smVariable.references) {
// TODO: if one of these is a return statement within the same function, it's handled.
const refNode = reference.identifier;
if (refNode === disposableNode) {
continue;
}
const refScope = context.sourceCode.getScope(refNode);
if (
refScope.variableScope === scope.variableScope &&
isValidWayToHandleDisposable(refNode)
) {
return true;
}
}
}

return false;
}

// return makeDisposable();
if (disposableNode.parent.type === AST_NODE_TYPES.ReturnStatement) {
return true;
}

return false;
}
},
});
111 changes: 111 additions & 0 deletions packages/eslint-plugin/tests/rules/no-misused-disposable.test.ts
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import { RuleTester } from '@typescript-eslint/rule-tester';

import rule from '../../src/rules/no-misused-disposable';
import { getFixturesRootDir } from '../RuleTester';

const rootPath = getFixturesRootDir();

const ruleTester = new RuleTester({
languageOptions: {
parserOptions: {
project: './tsconfig.json',
tsconfigRootDir: rootPath,
},
},
});

ruleTester.run('no-misused-disposable', rule, {
valid: [
`
declare function d(): Disposable;
using foo = d();
`,
`
declare function f(): void;
declare function d(): Disposable;
using foo = (f(), d());
`,
`
declare function ad(): AsyncDisposable;
async function f() {
await using foo = ad();
}
`,
`
declare function d(): Disposable;
function makeDisposable() {
return d();
}
`,
`
declare function d(): Disposable;
function makeDisposable() {
const x = d();
return x;
}
`,
// not all paths handle the disposable... should this flag?
`
declare function d(): Disposable;
function makeDisposable() {
const x = d();
if (Math.random() > 0.5) {
return x;
}
}
`,
],
invalid: [
{
code: `
declare function d(): Disposable;
const foo = d();
`,
errors: [
{
column: 13,
endColumn: 16,
endLine: 3,
line: 3,
messageId: 'misusedDisposable',
},
],
},
{
code: `
declare function f(): void;
declare function d(): Disposable;
const foo = (f(), d());
`,
errors: [
{
column: 19,
endColumn: 22,
endLine: 4,
line: 4,
messageId: 'misusedDisposable',
},
],
},
{
code: `
declare function d(): Disposable;
function makeDisposable() {
const x = d();
function inner() {
return x;
}
}
`,
errors: [
{
column: 13,
endColumn: 16,
endLine: 4,
line: 4,
messageId: 'misusedDisposable',
},
],
},
],
});
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