From 77aac87ddd8062c70c46aa47f8bd76ac91753c72 Mon Sep 17 00:00:00 2001
From: Vladimir <sleuths.slews0s@icloud.com>
Date: Mon, 10 Aug 2026 15:19:54 +0200
Subject: [PATCH] fix(typecheck): report a checker crash on Windows instead of
 a spawn failure (#10907)

---
 .../vitest/src/node/pools/workers/typecheckWorker.ts     | 5 ++---
 packages/vitest/src/typecheck/typechecker.ts             | 7 ++++++-
 test/typescript/fixtures/typecheck-crash/fake-tsc.cmd    | 2 ++
 test/typescript/test/typechecker.test.ts                 | 9 ++++++---
 4 files changed, 16 insertions(+), 7 deletions(-)
 create mode 100644 test/typescript/fixtures/typecheck-crash/fake-tsc.cmd

diff --git a/packages/vitest/src/node/pools/workers/typecheckWorker.ts b/packages/vitest/src/node/pools/workers/typecheckWorker.ts
index 954af48bd..3f099ddc7 100644
--- a/packages/vitest/src/node/pools/workers/typecheckWorker.ts
+++ b/packages/vitest/src/node/pools/workers/typecheckWorker.ts
@@ -7,7 +7,7 @@ import type { TestRunEndReason } from '../../types/reporter'
 import type { PoolOptions, PoolWorker, WorkerRequest, WorkerResponse } from '../types'
 import EventEmitter from 'node:events'
 import { createDefer } from '@vitest/utils/helpers'
-import { Typechecker } from '../../../typecheck/typechecker'
+import { OOM_OUTPUT_PATTERN, Typechecker } from '../../../typecheck/typechecker'
 import { hasFailed } from '../../../utils/tasks'
 
 /** @experimental */
@@ -130,8 +130,7 @@ function createRunner(vitest: Vitest) {
 
       if (exitCode || signal) {
         const output = checker.getOutput()
-        const looksLikeOom = signal === 'SIGABRT'
-          || /JavaScript heap out of memory|Reached heap limit|Allocation failed/i.test(output)
+        const looksLikeOom = signal === 'SIGABRT' || OOM_OUTPUT_PATTERN.test(output)
 
         let message: string
         if (signal || looksLikeOom) {
diff --git a/packages/vitest/src/typecheck/typechecker.ts b/packages/vitest/src/typecheck/typechecker.ts
index efbdf934d..9355db5b1 100644
--- a/packages/vitest/src/typecheck/typechecker.ts
+++ b/packages/vitest/src/typecheck/typechecker.ts
@@ -18,6 +18,9 @@ import { createLocationsIndexMap } from '../utils/base'
 import { convertTasksToEvents } from '../utils/tasks'
 import { getRawErrsMapFromTsCompile } from './parse'
 
+// the V8 fatal output of a checker that ran out of memory
+export const OOM_OUTPUT_PATTERN: RegExp = /JavaScript heap out of memory|Reached heap limit|Allocation failed/i
+
 export class TypeCheckError extends Error {
   name = 'TypeCheckError'
 
@@ -428,7 +431,9 @@ export class Typechecker {
 
       if (process.platform === 'win32') {
         child.process.once('close', (code) => {
-          if (code != null && code !== 0 && !dataReceived) {
+          // an OOM abort writes only to stderr, but the checker did start;
+          // `start` awaits the process and reports the crash from its output
+          if (code != null && code !== 0 && !dataReceived && !OOM_OUTPUT_PATTERN.test(this._output)) {
             onError(new Error(`The ${typecheck.checker} command exited with code ${code}.`))
           }
           else if (!resolved) {
diff --git a/test/typescript/fixtures/typecheck-crash/fake-tsc.cmd b/test/typescript/fixtures/typecheck-crash/fake-tsc.cmd
new file mode 100644
index 000000000..e3b5d003b
--- /dev/null
+++ b/test/typescript/fixtures/typecheck-crash/fake-tsc.cmd
@@ -0,0 +1,2 @@
+@rem Windows can't execute .mjs files directly, run the fake checker with node
+@node "%~dp0fake-tsc.mjs" %*
diff --git a/test/typescript/test/typechecker.test.ts b/test/typescript/test/typechecker.test.ts
index cff2d96ae..9e53a191a 100644
--- a/test/typescript/test/typechecker.test.ts
+++ b/test/typescript/test/typechecker.test.ts
@@ -23,15 +23,18 @@ describe('Typechecker', () => {
         enabled: true,
         checker: resolve(
           import.meta.dirname,
-          '../fixtures/typecheck-crash/fake-tsc.mjs',
+          // Windows can't execute an .mjs file, the .cmd shim runs it with node
+          process.platform === 'win32'
+            ? '../fixtures/typecheck-crash/fake-tsc.cmd'
+            : '../fixtures/typecheck-crash/fake-tsc.mjs',
         ),
       },
     })
 
     // A checker that aborts (OOM) without producing diagnostics must NOT be
     // reported as passing — the run has to fail with a clear error. The abort
-    // surfaces as a signal (SIGABRT) on POSIX and as exit code 134 on Windows;
-    // both paths must be treated as an abnormal, failing exit.
+    // surfaces as a signal (SIGABRT) on POSIX and as a non-zero exit code on
+    // Windows; both paths must be treated as an abnormal, failing exit.
     expect(exitCode).toBe(1)
     expect(stderr).toContain('Typecheck Error')
     expect(stderr).toContain('before type checking finished')
-- 
2.51.2