[libc++] Add thread safety annotations for std::lock #154078
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@llvm/pr-subscribers-libcxx Author: Nikolas Klauser (philnik777) ChangesFixes #151733 Full diff: https://github.com/llvm/llvm-project/pull/154078.diff 2 Files Affected:
diff --git a/libcxx/include/mutex b/libcxx/include/mutex
index 78d8c8a9bcc6e..3f546f039f4c7 100644
--- a/libcxx/include/mutex
+++ b/libcxx/include/mutex
@@ -351,7 +351,7 @@ _LIBCPP_HIDE_FROM_ABI int try_lock(_L0& __l0, _L1& __l1, _L2& __l2, _L3&... __l3
# endif // _LIBCPP_CXX03_LANG
template <class _L0, class _L1>
-_LIBCPP_HIDE_FROM_ABI void lock(_L0& __l0, _L1& __l1) {
+_LIBCPP_HIDE_FROM_ABI void lock(_L0& __l0, _L1& __l1) _LIBCPP_ACQUIRE_CAPABILITY(__l0, __l1) {
while (true) {
{
unique_lock<_L0> __u0(__l0);
@@ -411,7 +411,8 @@ void __lock_first(int __i, _L0& __l0, _L1& __l1, _L2& __l2, _L3&... __l3) {
}
template <class _L0, class _L1, class _L2, class... _L3>
-inline _LIBCPP_HIDE_FROM_ABI void lock(_L0& __l0, _L1& __l1, _L2& __l2, _L3&... __l3) {
+inline _LIBCPP_HIDE_FROM_ABI void lock(_L0& __l0, _L1& __l1, _L2& __l2, _L3&... __l3)
+ _LIBCPP_ACQUIRE_CAPABILITY(__l0, __l1, __l2, __l3...) {
std::__lock_first(0, __l0, __l1, __l2, __l3...);
}
diff --git a/libcxx/test/extensions/clang/thread/thread.mutex/lock.verify.cpp b/libcxx/test/extensions/clang/thread/thread.mutex/lock.verify.cpp
new file mode 100644
index 0000000000000..0b3f87068589a
--- /dev/null
+++ b/libcxx/test/extensions/clang/thread/thread.mutex/lock.verify.cpp
@@ -0,0 +1,43 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: no-threads
+
+// <mutex>
+
+// GCC doesn't have thread safety attributes
+// UNSUPPORTED: gcc
+
+// ADDITIONAL_COMPILE_FLAGS: -Wthread-safety -Wno-comment
+
+// XFAIL: FROZEN-CXX03-HEADERS-FIXME
+
+#include <mutex>
+
+std::mutex m0;
+std::mutex m1;
+std::mutex m2;
+std::mutex m3;
+
+void f1() {
+ std::lock(m0, m1);
+} // expected-warning {{mutex 'm0' is still held at the end of function}} \
+ expected-warning {{mutex 'm1' is still held at the end of function}}
+
+void f2() {
+ std::lock(m0, m1, m2);
+} // expected-warning {{mutex 'm0' is still held at the end of function}} \
+ expected-warning {{mutex 'm1' is still held at the end of function}} \
+ expected-warning {{mutex 'm2' is still held at the end of function}}
+
+void f3() {
+ std::lock(m0, m1, m2, m3);
+} // expected-warning {{mutex 'm0' is still held at the end of function}} \
+ expected-warning {{mutex 'm1' is still held at the end of function}} \
+ expected-warning {{mutex 'm2' is still held at the end of function}} \
+ expected-warning {{mutex 'm3' is still held at the end of function}}
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ldionne
approved these changes
Sep 2, 2025
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/cherry-pick 0a2eb85 |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/159/builds/30029 Here is the relevant piece of the build log for the reference |
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Failed to cherry-pick: 0a2eb85 https://github.com/llvm/llvm-project/actions/runs/17425303760 Please manually backport the fix and push it to your github fork. Once this is done, please create a pull request |
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Looks like that this PR missed handling for Apple Clang... |
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It looks like this patch leads to Do more |
PiJoules
added a commit
to PiJoules/llvm-project
that referenced
this pull request
Sep 4, 2025
…4078)" This reverts commit 0a2eb85. Reverting because this leads to a false positive with -Wthread-safety. See llvm#156760.
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Fixes #151733