[libcxx-commits] [libcxx] [libc++][windows] Use _wsetlocale() in __locale_guard (PR #160479)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libcxx

Author: None (lb90)

<details>
<summary>Changes</summary>

Querying the current locale string on Windows should always be done with _wsetlocale(). The OS and the CRT support localized language and country names, for example "Norwegian Bokmål_Norway". Narrow setlocale doesn't know what's the expected encoding.

Fixes #<!-- -->160478

---
Full diff: https://github.com/llvm/llvm-project/pull/160479.diff


1 Files Affected:

- (modified) libcxx/include/__locale_dir/support/windows.h (+13-3) 


``````````diff
diff --git a/libcxx/include/__locale_dir/support/windows.h b/libcxx/include/__locale_dir/support/windows.h
index 0df8709f118d0..1d54d4cb119e0 100644
--- a/libcxx/include/__locale_dir/support/windows.h
+++ b/libcxx/include/__locale_dir/support/windows.h
@@ -162,6 +162,12 @@ inline _LIBCPP_HIDE_FROM_ABI char* __setlocale(int __category, const char* __loc
     std::__throw_bad_alloc();
   return __new_locale;
 }
+inline _LIBCPP_HIDE_FROM_ABI wchar_t* __wsetlocale(int __category, const wchar_t* __locale) {
+  wchar_t* __new_locale = ::_wsetlocale(__category, __locale);
+  if (__new_locale == nullptr)
+    std::__throw_bad_alloc();
+  return __new_locale;
+}
 _LIBCPP_EXPORTED_FROM_ABI __lconv_t* __localeconv(__locale_t& __loc);
 #endif // _LIBCPP_BUILDING_LIBRARY
 
@@ -309,7 +315,11 @@ struct __locale_guard {
     // each category.  In the second case, we know at least one category won't
     // be what we want, so we only have to check the first case.
     if (std::strcmp(__l.__get_locale(), __lc) != 0) {
-      __locale_all = _strdup(__lc);
+      // Use wsetlocale to query the current locale string. This avoids a lossy
+      // conversion of the locale string from UTF-16 to the current LC_CTYPE
+      // charset. The Windows CRT allows language/country strings outside of
+      // ASCII, e.g. "Norwegian Bokmål_Norway.utf8"
+      __locale_all = _wcsdup(__locale::__wsetlocale(LC_ALL, nullptr));
       if (__locale_all == nullptr)
         std::__throw_bad_alloc();
       __locale::__setlocale(LC_ALL, __l.__get_locale());
@@ -321,13 +331,13 @@ struct __locale_guard {
     // for the different categories in the same format as returned by
     // setlocale(LC_ALL, nullptr).
     if (__locale_all != nullptr) {
-      __locale::__setlocale(LC_ALL, __locale_all);
+      __locale::__wsetlocale(LC_ALL, __locale_all);
       free(__locale_all);
     }
     _configthreadlocale(__status);
   }
   int __status;
-  char* __locale_all = nullptr;
+  wchar_t* __locale_all = nullptr;
 };
 #endif // _LIBCPP_BUILDING_LIBRARY
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/160479