[gcc r12-10252] libstdc++: Fix exception thrown by std::shared_lock::unlock() [PR112089]

[gcc r12-10252] libstdc++: Fix exception thrown by std::shared_lock::unlock() [PR112089]

[Jonathan Wakely]

https://gcc.gnu.org/g:c285c1b9a940bde745f296e1bfc1a5cfddb63254

commit r12-10252-gc285c1b9a940bde745f296e1bfc1a5cfddb63254
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Oct 26 16:51:30 2023 +0100

    libstdc++: Fix exception thrown by std::shared_lock::unlock() [PR112089]
    
    The incorrect errc constant here looks like a copy&paste error.
    
    libstdc++-v3/ChangeLog:
    
            PR libstdc++/112089
            * include/std/shared_mutex (shared_lock::unlock): Change errc
            constant to operation_not_permitted.
            * testsuite/30_threads/shared_lock/locking/112089.cc: New test.
    
    (cherry picked from commit 0c305f3dec9a992dd775a3b9607b7b1e8c051859)

Diff:
---
 libstdc++-v3/include/std/shared_mutex              |  2 +-
 .../30_threads/shared_lock/locking/112089.cc       | 23 ++++++++++++++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/libstdc++-v3/include/std/shared_mutex b/libstdc++-v3/include/std/shared_mutex
index 817a9587d87..0a61bedbe12 100644
--- a/libstdc++-v3/include/std/shared_mutex
+++ b/libstdc++-v3/include/std/shared_mutex
@@ -801,7 +801,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       unlock()
       {
 	if (!_M_owns)
-	  __throw_system_error(int(errc::resource_deadlock_would_occur));
+	  __throw_system_error(int(errc::operation_not_permitted));
 	_M_pm->unlock_shared();
 	_M_owns = false;
       }
diff --git a/libstdc++-v3/testsuite/30_threads/shared_lock/locking/112089.cc b/libstdc++-v3/testsuite/30_threads/shared_lock/locking/112089.cc
new file mode 100644
index 00000000000..432c17591a1
--- /dev/null
+++ b/libstdc++-v3/testsuite/30_threads/shared_lock/locking/112089.cc
@@ -0,0 +1,23 @@
+// { dg-do run { target c++14 } }
+// { dg-require-gthreads "" }
+// { dg-additional-options "-pthread" { target pthread } }
+
+#include <shared_mutex>
+#include <system_error>
+#include <testsuite_hooks.h>
+
+// PR libstdc++/112089 shared_lock::unlock should throw operation_not_permitted
+
+int main()
+{
+  std::shared_lock<std::shared_timed_mutex> l;
+  try
+  {
+    l.unlock();
+    VERIFY( false );
+  }
+  catch (const std::system_error& e)
+  {
+    VERIFY( e.code() == std::errc::operation_not_permitted );
+  }
+}