Oct 24, 2022 · Oct 24, 2022 · Oct 24, 2022 · Oct 24, 2022
diff --git a/packages/eslint-plugin/src/rules/no-unsafe-declaration-merging.ts b/packages/eslint-plugin/src/rules/no-unsafe-declaration-merging.ts
 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';

    docs: {
      description: 'Disallow unsafe declaration merging',
      recommended: 'strict',
      requiresTypeChecking:true,
      requiresTypeChecking:false,
    },
    messages: {
      unsafeMerging:
  },
  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',
    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,
        );
      },
    };
  },
diff --git a/packages/eslint-plugin/tests/rules/no-unsafe-declaration-merging.test.ts b/packages/eslint-plugin/tests/rules/no-unsafe-declaration-merging.test.ts
    },
    {
      code: `
 namespace Foo {
  export interface Bar {}
 }
 namespace Foo {
  export class Bar {}
 }
 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,
        },
      ],
    },
Original file line number	Diff line number	Diff line change
		@@ -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,
		);
		},
		};
		},
Expand Down
Original file line number	Diff line number	Diff line change
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 Copy link MemberAuthor bradzacherOct 24, 2022 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. 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. yeonjuan reacted with thumbs up emoji Copy link Contributor yeonjuanOct 24, 2022• edited Loading Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. it seems good trade off. i tried to handle these kinds of cases but i couldn't finish until now 😅 bradzacher reacted with thumbs up emoji
		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