[libc++] Improves _LIBCPP_HAS_NO_THREADS guards.

libcxx/include/barrier

@@ -45,11 +45,16 @@ namespace std
 
 */
 
+#include <__config>
+
+#ifdef _LIBCPP_HAS_NO_THREADS
+#  error "<barrier> is not supported since libc++ has been configured without support for threads."
+#endif
+
 #include <__assert> // all public C++ headers provide the assertion handler
 #include <__atomic/atomic_base.h>
 #include <__atomic/memory_order.h>
 #include <__availability>
-#include <__config>
 #include <__memory/unique_ptr.h>
 #include <__thread/poll_with_backoff.h>
 #include <__thread/timed_backoff_policy.h>
@@ -63,10 +68,6 @@ namespace std
 #  pragma GCC system_header
 #endif
 
-#ifdef _LIBCPP_HAS_NO_THREADS
-#  error "<barrier> is not supported since libc++ has been configured without support for threads."
-#endif
-
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 

libcxx/include/future

@@ -362,11 +362,16 @@ template <class R, class Alloc> struct uses_allocator<packaged_task<R>, Alloc>;
 
 */
 
+#include <__config>
+
+#ifdef _LIBCPP_HAS_NO_THREADS
+#  error "<future> is not supported since libc++ has been configured without support for threads."
+#endif
+
 #include <__assert> // all public C++ headers provide the assertion handler
 #include <__availability>
 #include <__chrono/duration.h>
 #include <__chrono/time_point.h>
-#include <__config>
 #include <__exception/exception_ptr.h>
 #include <__memory/addressof.h>
 #include <__memory/allocator.h>
@@ -396,10 +401,6 @@ template <class R, class Alloc> struct uses_allocator<packaged_task<R>, Alloc>;
 #  pragma GCC system_header
 #endif
 
-#ifdef _LIBCPP_HAS_NO_THREADS
-#  error "<future> is not supported since libc++ has been configured without support for threads."
-#endif
-
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 // enum class future_errc

libcxx/include/latch

@@ -40,12 +40,17 @@ namespace std
 
 */
 
+#include <__config>
+
+#ifdef _LIBCPP_HAS_NO_THREADS
+#  error "<latch> is not supported since libc++ has been configured without support for threads."
+#endif
+
 #include <__assert> // all public C++ headers provide the assertion handler
 #include <__atomic/atomic_base.h>
 #include <__atomic/atomic_sync.h>
 #include <__atomic/memory_order.h>
 #include <__availability>
-#include <__config>
 #include <cstddef>
 #include <limits>
 #include <version>
@@ -54,10 +59,6 @@ namespace std
 #  pragma GCC system_header
 #endif
 
-#ifdef _LIBCPP_HAS_NO_THREADS
-#  error "<latch> is not supported since libc++ has been configured without support for threads."
-#endif
-
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 

libcxx/include/semaphore

@@ -45,13 +45,18 @@ using binary_semaphore = counting_semaphore<1>;
 
 */
 
+#include <__config>
+
+#ifdef _LIBCPP_HAS_NO_THREADS
+#  error "<semaphore> is not supported since libc++ has been configured without support for threads."
+#endif
+
 #include <__assert> // all public C++ headers provide the assertion handler
 #include <__atomic/atomic_base.h>
 #include <__atomic/atomic_sync.h>
 #include <__atomic/memory_order.h>
 #include <__availability>
 #include <__chrono/time_point.h>
-#include <__config>
 #include <__thread/poll_with_backoff.h>
 #include <__thread/timed_backoff_policy.h>
 #include <__threading_support>
@@ -63,10 +68,6 @@ using binary_semaphore = counting_semaphore<1>;
 #  pragma GCC system_header
 #endif
 
-#ifdef _LIBCPP_HAS_NO_THREADS
-#  error "<semaphore> is not supported since libc++ has been configured without support for threads."
-#endif
-
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 

libcxx/include/shared_mutex

@@ -122,13 +122,18 @@ template <class Mutex>
 
 */
 
+#include <__config>
+
+#  ifdef _LIBCPP_HAS_NO_THREADS
+#    error "<shared_mutex> is not supported since libc++ has been configured without support for threads."
+#  endif
+
 #include <__assert> // all public C++ headers provide the assertion handler
 #include <__availability>
 #include <__chrono/duration.h>
 #include <__chrono/steady_clock.h>
 #include <__chrono/time_point.h>
 #include <__condition_variable/condition_variable.h>
-#include <__config>
 #include <__memory/addressof.h>
 #include <__mutex/mutex.h>
 #include <__mutex/tag_types.h>
@@ -147,10 +152,6 @@ _LIBCPP_PUSH_MACROS
 #    pragma GCC system_header
 #  endif
 
-#  ifdef _LIBCPP_HAS_NO_THREADS
-#    error "<shared_mutex> is not supported since libc++ has been configured without support for threads."
-#  endif
-
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 struct _LIBCPP_EXPORTED_FROM_ABI __shared_mutex_base {

libcxx/include/stop_token

@@ -31,8 +31,13 @@ namespace std {
 
 */
 
-#include <__assert> // all public C++ headers provide the assertion handler
 #include <__config>
+
+#ifdef _LIBCPP_HAS_NO_THREADS
+#  error "<stop_token> is not supported since libc++ has been configured without support for threads."
+#endif
+
+#include <__assert> // all public C++ headers provide the assertion handler
 #include <__stop_token/stop_callback.h>
 #include <__stop_token/stop_source.h>
 #include <__stop_token/stop_token.h>
@@ -42,10 +47,6 @@ namespace std {
 #  pragma GCC system_header
 #endif
 
-#ifdef _LIBCPP_HAS_NO_THREADS
-#  error "<stop_token> is not supported since libc++ has been configured without support for threads."
-#endif
-
 #if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
 #  include <iosfwd>
 #endif

libcxx/include/thread

@@ -86,9 +86,14 @@ void sleep_for(const chrono::duration<Rep, Period>& rel_time);
 
 */
 
+#include <__config>
+
+#ifdef _LIBCPP_HAS_NO_THREADS
+#  error "<thread> is not supported since libc++ has been configured without support for threads."
+#endif
+
 #include <__assert> // all public C++ headers provide the assertion handler
 #include <__availability>
-#include <__config>
 #include <__thread/formatter.h>
 #include <__thread/jthread.h>
 #include <__thread/this_thread.h>
@@ -105,10 +110,6 @@ void sleep_for(const chrono::duration<Rep, Period>& rel_time);
 #  pragma GCC system_header
 #endif
 
-#ifdef _LIBCPP_HAS_NO_THREADS
-#  error "<thread> is not supported since libc++ has been configured without support for threads."
-#endif
-
 #if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES)
 #  include <cstddef>
 #  include <ctime>