[llvm] Fix thread handle leak on Windows (PR #156854)

[Lukasz Mielicki via llvm-commits]

https://github.com/lmielick created https://github.com/llvm/llvm-project/pull/156854

Contrary to pthread_join on Windows WaitForSingleObject does not destroy the thread handle. Add missing CloseHandle call to avoid a handle leak.

>From 2c1503de804ba2ef0d890dea0a70a7cf1e552430 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C5=81ukasz=20Mielicki?= <lukasz.mielicki at intel.com>
Date: Wed, 4 Jun 2025 11:55:12 +0200
Subject: [PATCH] Fix thread handle leak on Windows (#133)

---
 llvm/lib/Support/Windows/Threading.inc | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/llvm/lib/Support/Windows/Threading.inc b/llvm/lib/Support/Windows/Threading.inc
index b11f216adeba4..fd872a2b133e9 100644
--- a/llvm/lib/Support/Windows/Threading.inc
+++ b/llvm/lib/Support/Windows/Threading.inc
@@ -42,6 +42,9 @@ void llvm_thread_join_impl(HANDLE hThread) {
   if (::WaitForSingleObject(hThread, INFINITE) == WAIT_FAILED) {
     ReportLastErrorFatal("WaitForSingleObject failed");
   }
+  if (::CloseHandle(hThread) == FALSE) {
+    ReportLastErrorFatal("CloseHandle failed");
+  }
 }
 
 void llvm_thread_detach_impl(HANDLE hThread) {