diff --git a/libcxx/test/libcxx/input.output/file.streams/fstreams/fstream.cons/wchar_pointer.pass.cpp b/libcxx/test/libcxx/input.output/file.streams/fstreams/fstream.cons/wchar_pointer.pass.cpp
--- a/libcxx/test/libcxx/input.output/file.streams/fstreams/fstream.cons/wchar_pointer.pass.cpp
+++ b/libcxx/test/libcxx/input.output/file.streams/fstreams/fstream.cons/wchar_pointer.pass.cpp
@@ -13,14 +13,16 @@
 
 // explicit basic_fstream(const wchar_t* s, ios_base::openmode mode = ios_base::in | ios_base::out);
 
+// This extension is only provided on Windows.
+// REQUIRES: windows
+// UNSUPPORTED: no-wide-characters
+
 #include <fstream>
 #include <cassert>
 #include "test_macros.h"
-#include "platform_support.h"
+#include "wide_temp_file.h"
 
-int main(int, char**)
-{
-#ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
+int main(int, char**) {
     std::wstring temp = get_wide_temp_file_name();
     {
         std::fstream fs(temp.c_str(), std::ios_base::in | std::ios_base::out
@@ -42,7 +44,6 @@
         assert(x == 3.25);
     }
     _wremove(temp.c_str());
-#endif
 
-  return 0;
+    return 0;
 }
diff --git a/libcxx/test/libcxx/input.output/file.streams/fstreams/fstream.members/open_wchar_pointer.pass.cpp b/libcxx/test/libcxx/input.output/file.streams/fstreams/fstream.members/open_wchar_pointer.pass.cpp
--- a/libcxx/test/libcxx/input.output/file.streams/fstreams/fstream.members/open_wchar_pointer.pass.cpp
+++ b/libcxx/test/libcxx/input.output/file.streams/fstreams/fstream.members/open_wchar_pointer.pass.cpp
@@ -13,14 +13,16 @@
 
 // void open(const wchar_t* s, ios_base::openmode mode = ios_base::in|ios_base::out);
 
+// This extension is only provided on Windows.
+// REQUIRES: windows
+// UNSUPPORTED: no-wide-characters
+
 #include <fstream>
 #include <cassert>
 #include "test_macros.h"
-#include "platform_support.h"
+#include "wide_temp_file.h"
 
-int main(int, char**)
-{
-#ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
+int main(int, char**) {
     std::wstring temp = get_wide_temp_file_name();
     {
         std::fstream fs;
@@ -48,7 +50,6 @@
         assert(x == 3.25);
     }
     _wremove(temp.c_str());
-#endif
 
-  return 0;
+    return 0;
 }
diff --git a/libcxx/test/libcxx/input.output/file.streams/fstreams/ifstream.cons/wchar_pointer.pass.cpp b/libcxx/test/libcxx/input.output/file.streams/fstreams/ifstream.cons/wchar_pointer.pass.cpp
--- a/libcxx/test/libcxx/input.output/file.streams/fstreams/ifstream.cons/wchar_pointer.pass.cpp
+++ b/libcxx/test/libcxx/input.output/file.streams/fstreams/ifstream.cons/wchar_pointer.pass.cpp
@@ -13,6 +13,10 @@
 
 // explicit basic_ifstream(const wchar_t* s, ios_base::openmode mode = ios_base::in);
 
+// This extension is only provided on Windows.
+// REQUIRES: windows
+// UNSUPPORTED: no-wide-characters
+
 // FILE_DEPENDENCIES: test.dat
 
 #include <fstream>
@@ -20,9 +24,7 @@
 
 #include "test_macros.h"
 
-int main(int, char**)
-{
-#ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
+int main(int, char**) {
     {
         std::ifstream fs(L"test.dat");
         double x = 0;
@@ -41,7 +43,6 @@
     // std::wifstream(const wchar_t*, std::ios_base::openmode) is tested in
     // test/libcxx/input.output/file.streams/fstreams/ofstream.cons/wchar_pointer.pass.cpp
     // which creates writable files.
-#endif
 
-  return 0;
+    return 0;
 }
diff --git a/libcxx/test/libcxx/input.output/file.streams/fstreams/ifstream.members/open_wchar_pointer.pass.cpp b/libcxx/test/libcxx/input.output/file.streams/fstreams/ifstream.members/open_wchar_pointer.pass.cpp
--- a/libcxx/test/libcxx/input.output/file.streams/fstreams/ifstream.members/open_wchar_pointer.pass.cpp
+++ b/libcxx/test/libcxx/input.output/file.streams/fstreams/ifstream.members/open_wchar_pointer.pass.cpp
@@ -13,6 +13,10 @@
 
 // void open(const wchar_t* s, ios_base::openmode mode = ios_base::in);
 
+// This extension is only provided on Windows.
+// REQUIRES: windows
+// UNSUPPORTED: no-wide-characters
+
 // FILE_DEPENDENCIES: test.dat
 
 #include <fstream>
@@ -20,9 +24,7 @@
 
 #include "test_macros.h"
 
-int main(int, char**)
-{
-#ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
+int main(int, char**) {
     {
         std::ifstream fs;
         assert(!fs.is_open());
@@ -47,7 +49,6 @@
         fs >> c;
         assert(c == L'r');
     }
-#endif
 
-  return 0;
+    return 0;
 }
diff --git a/libcxx/test/libcxx/input.output/file.streams/fstreams/ofstream.cons/wchar_pointer.pass.cpp b/libcxx/test/libcxx/input.output/file.streams/fstreams/ofstream.cons/wchar_pointer.pass.cpp
--- a/libcxx/test/libcxx/input.output/file.streams/fstreams/ofstream.cons/wchar_pointer.pass.cpp
+++ b/libcxx/test/libcxx/input.output/file.streams/fstreams/ofstream.cons/wchar_pointer.pass.cpp
@@ -13,14 +13,16 @@
 
 // explicit basic_ofstream(const wchar_t* s, ios_base::openmode mode = ios_base::out);
 
+// This extension is only provided on Windows.
+// REQUIRES: windows
+// UNSUPPORTED: no-wide-characters
+
 #include <fstream>
 #include <cassert>
 #include "test_macros.h"
-#include "platform_support.h"
+#include "wide_temp_file.h"
 
-int main(int, char**)
-{
-#ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
+int main(int, char**) {
     std::wstring temp = get_wide_temp_file_name();
     {
         std::ofstream fs(temp.c_str());
@@ -56,7 +58,6 @@
         assert(x == 3.25);
     }
     _wremove(temp.c_str());
-#endif
 
-  return 0;
+    return 0;
 }
diff --git a/libcxx/test/libcxx/input.output/file.streams/fstreams/ofstream.members/open_wchar_pointer.pass.cpp b/libcxx/test/libcxx/input.output/file.streams/fstreams/ofstream.members/open_wchar_pointer.pass.cpp
--- a/libcxx/test/libcxx/input.output/file.streams/fstreams/ofstream.members/open_wchar_pointer.pass.cpp
+++ b/libcxx/test/libcxx/input.output/file.streams/fstreams/ofstream.members/open_wchar_pointer.pass.cpp
@@ -13,14 +13,16 @@
 
 // void open(const wchar_t* s, ios_base::openmode mode = ios_base::out);
 
+// This extension is only provided on Windows.
+// REQUIRES: windows
+// UNSUPPORTED: no-wide-characters
+
 #include <fstream>
 #include <cassert>
 #include "test_macros.h"
-#include "platform_support.h"
+#include "wide_temp_file.h"
 
-int main(int, char**)
-{
-#ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
+int main(int, char**) {
     std::wstring temp = get_wide_temp_file_name();
     {
         std::ofstream fs;
@@ -56,7 +58,6 @@
         assert(c == L'a');
     }
     _wremove(temp.c_str());
-#endif
 
-  return 0;
+    return 0;
 }
diff --git a/libcxx/test/support/platform_support.h b/libcxx/test/support/platform_support.h
--- a/libcxx/test/support/platform_support.h
+++ b/libcxx/test/support/platform_support.h
@@ -35,8 +35,6 @@
 
 #include <stdio.h>
 #include <stdlib.h>
-#include <codecvt>
-#include <locale>
 #include <string>
 #if defined(_WIN32)
 #   include <io.h> // _mktemp_s
@@ -85,17 +83,6 @@
 #endif
 }
 
-_LIBCPP_SUPPRESS_DEPRECATED_PUSH
-#ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
-inline
-std::wstring get_wide_temp_file_name()
-{
-    return std::wstring_convert<std::codecvt_utf8_utf16<wchar_t> >().from_bytes(
-        get_temp_file_name());
-}
-#endif // _LIBCPP_HAS_OPEN_WITH_WCHAR
-_LIBCPP_SUPPRESS_DEPRECATED_POP
-
 #if defined(_CS_GNU_LIBC_VERSION)
 inline bool glibc_version_less_than(char const* version) {
   std::string test_version = std::string("glibc ") + version;
diff --git a/libcxx/test/support/wide_temp_file.h b/libcxx/test/support/wide_temp_file.h
new file mode 100644
--- /dev/null
+++ b/libcxx/test/support/wide_temp_file.h
@@ -0,0 +1,27 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef TEST_SUPPORT_WIDE_TEMP_FILE_H
+#define TEST_SUPPORT_WIDE_TEMP_FILE_H
+
+#include <codecvt>
+#include <locale>
+#include <string>
+
+#include "platform_support.h"
+#include "test_macros.h"
+
+TEST_DIAGNOSTIC_PUSH
+TEST_CLANG_DIAGNOSTIC_IGNORED("-Wdeprecated-declarations")
+TEST_GCC_DIAGNOSTIC_IGNORED("-Wdeprecated-declarations")
+inline std::wstring get_wide_temp_file_name() {
+    return std::wstring_convert<std::codecvt_utf8_utf16<wchar_t> >().from_bytes(get_temp_file_name());
+}
+TEST_DIAGNOSTIC_POP
+
+#endif // TEST_SUPPORT_WIDE_TEMP_FILE_H
diff --git a/libcxx/utils/libcxx/test/features.py b/libcxx/utils/libcxx/test/features.py
--- a/libcxx/utils/libcxx/test/features.py
+++ b/libcxx/utils/libcxx/test/features.py
@@ -236,7 +236,7 @@
                                   when=lambda cfg, alts=alts: hasAnyLocale(cfg, alts)))
 
 
-# Add features representing the platform name: darwin, linux, windows, etc...
+# Add features representing the target platform name: darwin, linux, windows, etc...
 DEFAULT_FEATURES += [
   Feature(name='darwin', when=lambda cfg: '__APPLE__' in compilerMacros(cfg)),
   Feature(name='windows', when=lambda cfg: '_WIN32' in compilerMacros(cfg)),