[libcxx-commits] [libcxx] [libc++] Fix ABI tag on __str_to_float_c_locale exported specialisations on MinGW (PR #229456)

[via libcxx-commits]

https://github.com/Himadhith updated https://github.com/llvm/llvm-project/pull/229456

>From 63000e0de9cdfade694b3f4c134e0ebe3c06e556 Mon Sep 17 00:00:00 2001
From: himadhith <himadhith.v at ibm.com>
Date: Tue, 6 Oct 2026 11:18:24 -0400
Subject: [PATCH 1/2] [libc++] Fix ABI tag on __str_to_float_c_locale exported
 specialisations on MinGW

---
 libcxx/include/__locale_dir/support/windows.h | 20 +++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/libcxx/include/__locale_dir/support/windows.h b/libcxx/include/__locale_dir/support/windows.h
index e4a030c72e701..2d264c8665571 100644
--- a/libcxx/include/__locale_dir/support/windows.h
+++ b/libcxx/include/__locale_dir/support/windows.h
@@ -175,32 +175,40 @@ _LIBCPP_EXPORTED_FROM_ABI const char* __get_locale_encoding(__locale_t __loc);
 //
 
 // the *_l functions are prefixed on Windows, only available for msvcr80+, VS2005+
+#if defined(_LIBCPP_MSVCRT)
 template <class _FloatT>
 _LIBCPP_HIDE_FROM_ABI _FloatT __str_to_float_c_locale(const char* __nptr, char** __endptr);
-#if defined(_LIBCPP_MSVCRT)
 
 template <>
 inline _LIBCPP_HIDE_FROM_ABI float __str_to_float_c_locale<float>(const char* __nptr, char** __endptr) {
   return ::_strtof_l(__nptr, __endptr, __get_c_locale());
 }
 
+template <>
+inline _LIBCPP_HIDE_FROM_ABI double __str_to_float_c_locale<double>(const char* __nptr, char** __endptr) {
+  return ::_strtod_l(__nptr, __endptr, __get_c_locale());
+}
+
 template <>
 inline _LIBCPP_HIDE_FROM_ABI long double __str_to_float_c_locale<long double>(const char* __nptr, char** __endptr) {
   return ::_strtold_l(__nptr, __endptr, __get_c_locale());
 }
 #else
-template <>
-_LIBCPP_EXPORTED_FROM_ABI float __str_to_float_c_locale<float>(const char*, char**);
+template <class _FloatT>
+_FloatT __str_to_float_c_locale(const char* __nptr, char** __endptr);
 
 template <>
-_LIBCPP_EXPORTED_FROM_ABI long double __str_to_float_c_locale<long double>(const char*, char**);
-#endif
+_LIBCPP_EXPORTED_FROM_ABI float __str_to_float_c_locale<float>(const char*, char**);
 
 template <>
-inline _LIBCPP_HIDE_FROM_ABI double __str_to_float_c_locale<double>(const char* __nptr, char** __endptr) {
+_LIBCPP_HIDDEN inline double __str_to_float_c_locale<double>(const char* __nptr, char** __endptr) {
   return ::_strtod_l(__nptr, __endptr, __get_c_locale());
 }
 
+template <>
+_LIBCPP_EXPORTED_FROM_ABI long double __str_to_float_c_locale<long double>(const char*, char**);
+#endif
+
 //
 // Character manipulation functions
 //

>From e8734033c320198f86d8ef2255750e7606b73a76 Mon Sep 17 00:00:00 2001
From: himadhith <himadhith.v at ibm.com>
Date: Thu, 8 Oct 2026 00:56:29 -0400
Subject: [PATCH 2/2] Add comments with concise explanations

---
 libcxx/include/__locale_dir/support/windows.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libcxx/include/__locale_dir/support/windows.h b/libcxx/include/__locale_dir/support/windows.h
index 2d264c8665571..2920fab3f8472 100644
--- a/libcxx/include/__locale_dir/support/windows.h
+++ b/libcxx/include/__locale_dir/support/windows.h
@@ -194,12 +194,14 @@ inline _LIBCPP_HIDE_FROM_ABI long double __str_to_float_c_locale<long double>(co
   return ::_strtold_l(__nptr, __endptr, __get_c_locale());
 }
 #else
+// No _LIBCPP_HIDE_FROM_ABI as exported specialisations must not inherit abi_tag.
 template <class _FloatT>
 _FloatT __str_to_float_c_locale(const char* __nptr, char** __endptr);
 
 template <>
 _LIBCPP_EXPORTED_FROM_ABI float __str_to_float_c_locale<float>(const char*, char**);
 
+// _LIBCPP_HIDDEN not _LIBCPP_HIDE_FROM_ABI, can't add abi_tag when primary has none.
 template <>
 _LIBCPP_HIDDEN inline double __str_to_float_c_locale<double>(const char* __nptr, char** __endptr) {
   return ::_strtod_l(__nptr, __endptr, __get_c_locale());