[libc++] Handle threads-related .cpp files like we do all other source files (#71100)
Source files in libc++ are added to the CMake targets only if they are
required by the configuration. We do this pretty consistently for all
configurations like no-filesystem, no-random-device, etc. but we didn't
do it for no-threads. This patch makes this consistent for no-threads,
which is helpful in reducing the amount of work required to port libc++
to some platforms without threads.
Indeed, with the previous approach, several threads-related source files
would end up including headers that might fail to compile properly on
some platforms. This issue is sidestepped entirely by making the
approach for no-threads consistent with the other configurations.
diff --git a/libcxx/src/shared_mutex.cpp b/libcxx/src/shared_mutex.cpp
index 49a51e0..1a346dd 100644
--- a/libcxx/src/shared_mutex.cpp
+++ b/libcxx/src/shared_mutex.cpp
@@ -6,15 +6,11 @@
//
//===----------------------------------------------------------------------===//
-#include <__config>
-
-#ifndef _LIBCPP_HAS_NO_THREADS
-
-# include <mutex>
-# include <shared_mutex>
-# if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
-# pragma comment(lib, "pthread")
-# endif
+#include <mutex>
+#include <shared_mutex>
+#if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
+# pragma comment(lib, "pthread")
+#endif
_LIBCPP_BEGIN_NAMESPACE_STD
@@ -95,5 +91,3 @@
void shared_timed_mutex::unlock_shared() { return __base_.unlock_shared(); }
_LIBCPP_END_NAMESPACE_STD
-
-#endif // !_LIBCPP_HAS_NO_THREADS
