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feat(eslint-plugin): [no-unsafe-declaration-merging] switch to use scope analysis instead of type information #5865

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merged 1 commit into from Oct 24, 2022
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feat(eslint-plugin): [no-unsafe-declaration-merging] switch to use scope analysis instead of type information #5865

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45 changes: 33 additions & 12 deletions packages/eslint-plugin/src/rules/no-unsafe-declaration-merging.ts
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@@ -1,5 +1,6 @@
import type { Scope } from '@typescript-eslint/scope-manager';
import type { TSESTree } from '@typescript-eslint/utils';
import * as ts from 'typescript';
import { AST_NODE_TYPES } from '@typescript-eslint/utils';

import * as util from '../util';

Expand All @@ -10,7 +11,7 @@ export default util.createRule({
docs: {
description: 'Disallow unsafe declaration merging',
recommended: 'strict',
requiresTypeChecking: true,
requiresTypeChecking: false,
},
messages: {
unsafeMerging:
Expand All @@ -20,17 +21,22 @@ export default util.createRule({
},
defaultOptions: [],
create(context) {
const parserServices = util.getParserServices(context);
const checker = parserServices.program.getTypeChecker();

function checkUnsafeDeclaration(
scope: Scope,
node: TSESTree.Identifier,
unsafeKind: ts.SyntaxKind,
unsafeKind: AST_NODE_TYPES,
): void {
const tsNode = parserServices.esTreeNodeToTSNodeMap.get(node);
const type = checker.getTypeAtLocation(tsNode);
const symbol = type.getSymbol();
if (symbol?.declarations?.some(decl => decl.kind === unsafeKind)) {
const variable = scope.set.get(node.name);
if (!variable) {
return;
}

const defs = variable.defs;
if (defs.length <= 1) {
return;
}

if (defs.some(def => def.node.type === unsafeKind)) {
context.report({
node,
messageId: 'unsafeMerging',
Expand All @@ -41,11 +47,26 @@ export default util.createRule({
return {
ClassDeclaration(node): void {
if (node.id) {
checkUnsafeDeclaration(node.id, ts.SyntaxKind.InterfaceDeclaration);
// by default eslint returns the inner class scope for the ClassDeclaration node
// but we want the outer scope within which merged variables will sit
const currentScope = context.getScope().upper;
if (currentScope == null) {
return;
}

checkUnsafeDeclaration(
currentScope,
node.id,
AST_NODE_TYPES.TSInterfaceDeclaration,
);
}
},
TSInterfaceDeclaration(node): void {
checkUnsafeDeclaration(node.id, ts.SyntaxKind.ClassDeclaration);
checkUnsafeDeclaration(
context.getScope(),
node.id,
AST_NODE_TYPES.ClassDeclaration,
);
},
};
},
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16 changes: 6 additions & 10 deletions packages/eslint-plugin/tests/rules/no-unsafe-declaration-merging.test.ts
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Expand Up @@ -80,23 +80,19 @@ class Foo {}
},
{
code: `
namespace Foo {
export interface Bar {}
}
namespace Foo {
export class Bar {}
}
Comment on lines -83 to -88
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note - we can no longer detect cases like this (as I mentioned here #5854 (comment)).

I think this is an okay trade-off as it should be really rare that someone is declaration merging via a declaration merged namespace.

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@yeonjuan yeonjuan Oct 24, 2022 •
edited

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it seems good trade off. i tried to handle these kinds of cases but i couldn't finish until now 😅

class Foo {}
interface Foo {}
`,
errors: [
{
messageId: 'unsafeMerging',
line: 3,
column: 20,
line: 2,
column: 7,
},
{
messageId: 'unsafeMerging',
line: 6,
column: 16,
line: 3,
column: 11,
},
],
},
Expand Down