From ead6e3dca74b8449ad16f690868e32297163a238 Mon Sep 17 00:00:00 2001
From: Yuta Saito <kateinoigakukun@gmail.com>
Date: Thu, 2 Jun 2022 06:25:37 +0000
Subject: [PATCH] [Threading] Use raw gettid syscall for older glibc
 compatibility

`gettid` wrapper was added in glibc 2.30, and Ubuntu 18.04 uses glibc
2.27, so use raw syscall instead of it.
---
 include/swift/Threading/Impl/Linux/ulock.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/swift/Threading/Impl/Linux/ulock.h b/include/swift/Threading/Impl/Linux/ulock.h
index 1219c52a1d91b..a9020965ec5d4 100644
--- a/include/swift/Threading/Impl/Linux/ulock.h
+++ b/include/swift/Threading/Impl/Linux/ulock.h
@@ -46,7 +46,7 @@ typedef std::int32_t ulock_t;
 inline int ulock_get_tid(void) {
   static __thread int tid;
   if (tid == 0)
-    tid = gettid();
+    tid = syscall(SYS_gettid);
   return tid;
 }