TS5097 is not reported for `require()` in checked JS or for clause-less side-effect imports

[ekazakov14]

Regression from typescript@6.0.2 to typescript@7.0.2. Also reproduces on @typescript/native-preview@7.0.0-dev.20260707.2 and on current main. node v24.13.0, darwin/arm64.

Steps to reproduce

Three files, no tsconfig.json:

lib.ts

export const value = 1;

require.js

// @ts-check
const { value } = require('./lib.ts');
console.log(value);

side-effect.ts

import './lib.ts';

tsc --noEmit --allowJs require.js side-effect.ts

Behavior with typescript@6.0.2

require.js(2,27): error TS5097: An import path can only end with a '.ts' extension when 'allowImportingTsExtensions' is enabled.
side-effect.ts(1,8): error TS5097: An import path can only end with a '.ts' extension when 'allowImportingTsExtensions' is enabled.

Behavior with typescript@7.0.2

No output — both are silently accepted.

This is not a module-resolution difference: 7.0 resolves require('./lib.ts') and type-checks against it. Changing console.log(value) to value(123) yields the same TS2349 from both versions at the same position — only TS5097 is missing.

Root cause

The two versions guard the diagnostic differently:

7.0 — tsc/internal/checker/checker.go:15334    if ast.FindAncestor(location, ast.IsEmittableImport) != nil {
6.0 — src/compiler/checker.ts:4779             if (errorNode && !(importOrExport?.isTypeOnly || findAncestor(location, isImportTypeNode))) {

7.0 asks "will this import survive emit?"; 6.0 asks "is this explicitly type-only?". The answers differ for exactly two shapes: a CommonJS require(), which is a plain CallExpression that IsEmittableImport never matched, and a clause-less side-effect import, which stopped matching in typescript-go#1198 — a fix for typescript-go#1190 in the adjacent .d.ts branch, which shares the same predicate.

Full matrix

case	6.0.2	7.0.2
require('./lib.ts') in checked JS	TS5097	—
import './lib.ts'	TS5097	—
import { value } from './lib.ts'	TS5097	TS5097
import { value } from './lib.ts' in JS	TS5097	TS5097
export { value } from './lib.ts'	TS5097	TS5097
import('./lib.ts')	TS5097	TS5097
import lib = require('./lib.ts')	TS5097	TS5097
import type { Thing } from './lib.ts'	—	—
export type { Thing } from './lib.ts'	—	—
import('./lib.ts').Thing in type position	—	—
import './types.d.ts'	—	—

The versions disagree only on the first two rows; the last four are negative cases where both correctly stay silent.