[libcxx] [test] Fix the locale ctype widen tests on Windows

[mstorsjo]

Summary

On Windows, like on macOS and FreeBSD, widening char(-5) succeeds
and produces L'\u00fb'.

This is the last instance of LIBCXX-WINDOWS-FIXME.

Unfortunately, this one can't be applied quite yet, it exposes
a bug in mingw-w64's btowc, fixed in
https://github.com/mingw-w64/mingw-w64/commit/707c3b81f77dd4d3b7124796a1e3f420b05c39e5. But once the CI environment is updated to a newer version
of the mingw toolchain (which we can do e.g. after LLVM 14.0.0
is released) we'll get this fix included. Putting it up for
review now already so that we can get it reviwed and done, ready
to land once the CI environment is updated.

[Mordante]

Great that this completes the removal of LIBCXX-WINDOWS-FIXME!
LGTM!

[• Quuxplusone]

Sure, LGTM in principle. Please make sure you get a green CI run (or two!) before actually landing this, though. As you say above, that might take a while.

[mstorsjo]

Rebased, rerunning CI. The CI environment should have been updated to a newer version so that this should pass now.

In the previously failing mingw config, which now is mostly working, another minor difference was uncovered by the switch from old to new style windows testing configs as default (I previously tested it with the old style test configs when testing locally outside of CI).

The mingw implementation of btowc differs in how it widens \x85 compared to Microsoft CRT's implementation of the same function, which hadn't been noticed in test setups with the old test configs.

Therefore, switch widen_many to test using \xfb which is the same as the widen_1 test uses (which tests with char(-5)), which is unambiguous across the Windows implementations of btowc.

@Mordante, can you ack the updated tests, even if the patch itself already was preapproved a couple weeks ago?

[Mordante]

Still LGTM!

libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/widen_1.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 
 // REQUIRES: locale.en_US.UTF-8
-// XFAIL: LIBCXX-WINDOWS-FIXME
 // XFAIL: LIBCXX-AIX-FIXME
 // XFAIL: libcpp-has-no-wide-characters
 
 // <locale>
 
 // template <class charT> class ctype_byname;
 
 // charT widen(char c) const;
int main(int, char**)
             const F& f = std::use_facet<F>(ll);
 
             assert(f.widen(' ') == L' ');
             assert(f.widen('A') == L'A');
             assert(f.widen('\x07') == L'\x07');
             assert(f.widen('.') == L'.');
             assert(f.widen('a') == L'a');
             assert(f.widen('1') == L'1');
-#if defined(__APPLE__) || defined(__FreeBSD__)
+#if defined(__APPLE__) || defined(__FreeBSD__) || defined(_WIN32)
             assert(f.widen(char(-5)) == L'\u00fb');
 #else
             assert(f.widen(char(-5)) == wchar_t(-1));
 #endif
         }
     }
 
   return 0;
 }

libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/widen_many.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 
 // REQUIRES: locale.en_US.UTF-8
-// XFAIL: LIBCXX-WINDOWS-FIXME
 // XFAIL: LIBCXX-AIX-FIXME
 // XFAIL: libcpp-has-no-wide-characters
 
 // <locale>
 
 // template <class charT> class ctype_byname;
 
 // const char* widen(const char* low, const char* high, charT* to) const;

 int main(int, char**)
 {
     {
         std::locale l(LOCALE_en_US_UTF_8);
         {
             typedef std::ctype_byname<wchar_t> F;
             std::locale ll(l, new F(LOCALE_en_US_UTF_8));
             F const& f = std::use_facet<F>(ll);
-            std::string in(" A\x07.a1\x85");
+            std::string in(" A\x07.a1\xfb");
             std::vector<wchar_t> v(in.size());
 
             assert(f.widen(&in[0], in.data() + in.size(), v.data()) == in.data() + in.size());
             assert(v[0] == L' ');
             assert(v[1] == L'A');
             assert(v[2] == L'\x07');
             assert(v[3] == L'.');
             assert(v[4] == L'a');
             assert(v[5] == L'1');
             assert(v[6] == wchar_t(-1));
         }
     }
     {
         std::locale l("C");
         {
             typedef std::ctype_byname<wchar_t> F;
             std::locale ll(l, new F("C"));
             const F& f = std::use_facet<F>(ll);
-            std::string in(" A\x07.a1\x85");
+            std::string in(" A\x07.a1\xfb");
             std::vector<wchar_t> v(in.size());
 
             assert(f.widen(&in[0], in.data() + in.size(), v.data()) == in.data() + in.size());
             assert(v[0] == L' ');
             assert(v[1] == L'A');
             assert(v[2] == L'\x07');
             assert(v[3] == L'.');
             assert(v[4] == L'a');
             assert(v[5] == L'1');
-#if defined(__APPLE__) || defined(__FreeBSD__)
-            assert(v[6] == L'\x85');
+#if defined(__APPLE__) || defined(__FreeBSD__) || defined(_WIN32)
+            assert(v[6] == L'\xfb');
 #else
             assert(v[6] == wchar_t(-1));
 #endif
         }
     }
 
   return 0;
 }