[libc++] Remove unnecessary #ifdef guards around PSTL implementation details (#95268)

We want the PSTL implementation details to be available regardless of
the Standard mode or whether the experimental PSTL is enabled. This
patch guards the inclusion of the PSTL to the top-level headers that
define the public API in `__numeric` and `__algorithm`.

Author: ldionne

libcxx/include/__algorithm/pstl.h

@@ -10,17 +10,6 @@
 #define _LIBCPP___ALGORITHM_PSTL_H
 
 #include <__config>
-#include <__functional/operations.h>
-#include <__iterator/cpp17_iterator_concepts.h>
-#include <__iterator/iterator_traits.h>
-#include <__pstl/backend.h>
-#include <__pstl/dispatch.h>
-#include <__pstl/handle_exception.h>
-#include <__type_traits/enable_if.h>
-#include <__type_traits/is_execution_policy.h>
-#include <__type_traits/remove_cvref.h>
-#include <__utility/forward.h>
-#include <__utility/move.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
@@ -31,6 +20,18 @@ _LIBCPP_PUSH_MACROS
 
 #if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
 
+#  include <__functional/operations.h>
+#  include <__iterator/cpp17_iterator_concepts.h>
+#  include <__iterator/iterator_traits.h>
+#  include <__pstl/backend.h>
+#  include <__pstl/dispatch.h>
+#  include <__pstl/handle_exception.h>
+#  include <__type_traits/enable_if.h>
+#  include <__type_traits/is_execution_policy.h>
+#  include <__type_traits/remove_cvref.h>
+#  include <__utility/forward.h>
+#  include <__utility/move.h>
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 template <class _ExecutionPolicy,

libcxx/include/__numeric/pstl.h

@@ -10,18 +10,6 @@
 #define _LIBCPP___NUMERIC_PSTL_H
 
 #include <__config>
-#include <__functional/identity.h>
-#include <__functional/operations.h>
-#include <__iterator/cpp17_iterator_concepts.h>
-#include <__iterator/iterator_traits.h>
-#include <__pstl/backend.h>
-#include <__pstl/dispatch.h>
-#include <__pstl/handle_exception.h>
-#include <__type_traits/enable_if.h>
-#include <__type_traits/is_execution_policy.h>
-#include <__type_traits/remove_cvref.h>
-#include <__utility/forward.h>
-#include <__utility/move.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
@@ -32,6 +20,19 @@ _LIBCPP_PUSH_MACROS
 
 #if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
 
+#  include <__functional/identity.h>
+#  include <__functional/operations.h>
+#  include <__iterator/cpp17_iterator_concepts.h>
+#  include <__iterator/iterator_traits.h>
+#  include <__pstl/backend.h>
+#  include <__pstl/dispatch.h>
+#  include <__pstl/handle_exception.h>
+#  include <__type_traits/enable_if.h>
+#  include <__type_traits/is_execution_policy.h>
+#  include <__type_traits/remove_cvref.h>
+#  include <__utility/forward.h>
+#  include <__utility/move.h>
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 template <class _ExecutionPolicy,

libcxx/include/__pstl/backends/default.h

@@ -33,8 +33,6 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
 _LIBCPP_BEGIN_NAMESPACE_STD
 namespace __pstl {
 
@@ -500,8 +498,6 @@ struct __rotate_copy<__default_backend_tag, _ExecutionPolicy> {
 } // namespace __pstl
 _LIBCPP_END_NAMESPACE_STD
 
-#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___PSTL_BACKENDS_DEFAULT_H

libcxx/include/__pstl/backends/libdispatch.h

@@ -44,8 +44,6 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
 _LIBCPP_BEGIN_NAMESPACE_STD
 namespace __pstl {
 
@@ -142,15 +140,15 @@ struct __cpu_traits<__libdispatch_backend_tag> {
 
     unique_ptr<__merge_range_t[], decltype(__destroy)> __ranges(
         [&]() -> __merge_range_t* {
-#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
           try {
-#  endif
+#endif
             return std::allocator<__merge_range_t>().allocate(__n_ranges);
-#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
           } catch (const std::bad_alloc&) {
             return nullptr;
           }
-#  endif
+#endif
         }(),
         __destroy);
 
@@ -394,8 +392,6 @@ struct __fill<__libdispatch_backend_tag, _ExecutionPolicy>
 } // namespace __pstl
 _LIBCPP_END_NAMESPACE_STD
 
-#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___PSTL_BACKENDS_LIBDISPATCH_H

libcxx/include/__pstl/backends/serial.h

@@ -27,10 +27,8 @@
 #  pragma GCC system_header
 #endif
 
-#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
 _LIBCPP_PUSH_MACROS
-#  include <__undef_macros>
+#include <__undef_macros>
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 namespace __pstl {
@@ -180,6 +178,4 @@ _LIBCPP_END_NAMESPACE_STD
 
 _LIBCPP_POP_MACROS
 
-#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && && _LIBCPP_STD_VER >= 17
-
 #endif // _LIBCPP___PSTL_BACKENDS_SERIAL_H

libcxx/include/__pstl/backends/std_thread.h

@@ -32,8 +32,6 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
 _LIBCPP_BEGIN_NAMESPACE_STD
 namespace __pstl {
 
@@ -133,8 +131,6 @@ struct __fill<__std_thread_backend_tag, _ExecutionPolicy>
 } // namespace __pstl
 _LIBCPP_END_NAMESPACE_STD
 
-#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && && _LIBCPP_STD_VER >= 17
-
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___PSTL_BACKENDS_STD_THREAD_H

libcxx/include/__pstl/cpu_algos/any_of.h

@@ -23,10 +23,8 @@
 #include <cstdint>
 #include <optional>
 
-#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
 _LIBCPP_PUSH_MACROS
-#  include <__undef_macros>
+#include <__undef_macros>
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 namespace __pstl {
@@ -98,6 +96,4 @@ _LIBCPP_END_NAMESPACE_STD
 
 _LIBCPP_POP_MACROS
 
-#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
 #endif // _LIBCPP___PSTL_CPU_ALGOS_ANY_OF_H

libcxx/include/__pstl/cpu_algos/fill.h

@@ -23,8 +23,6 @@
 #  pragma GCC system_header
 #endif
 
-#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
 _LIBCPP_BEGIN_NAMESPACE_STD
 namespace __pstl {
 
@@ -65,6 +63,4 @@ struct __cpu_parallel_fill {
 } // namespace __pstl
 _LIBCPP_END_NAMESPACE_STD
 
-#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
 #endif // _LIBCPP___PSTL_CPU_ALGOS_FILL_H

libcxx/include/__pstl/cpu_algos/find_if.h

@@ -28,10 +28,8 @@
 #  pragma GCC system_header
 #endif
 
-#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
 _LIBCPP_PUSH_MACROS
-#  include <__undef_macros>
+#include <__undef_macros>
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 namespace __pstl {
@@ -136,6 +134,4 @@ _LIBCPP_END_NAMESPACE_STD
 
 _LIBCPP_POP_MACROS
 
-#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
 #endif // _LIBCPP___PSTL_CPU_ALGOS_FIND_IF_H

libcxx/include/__pstl/cpu_algos/for_each.h

@@ -23,8 +23,6 @@
 #  pragma GCC system_header
 #endif
 
-#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
 _LIBCPP_BEGIN_NAMESPACE_STD
 namespace __pstl {
 
@@ -65,6 +63,4 @@ struct __cpu_parallel_for_each {
 } // namespace __pstl
 _LIBCPP_END_NAMESPACE_STD
 
-#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
-
 #endif // _LIBCPP___PSTL_CPU_ALGOS_FOR_EACH_H