[libc++] Guard <codecvt> contents on _LIBCPP_HAS_LOCALIZATION

[ldionne]

The codecvt class is defined in and the contents of the header don't work when localization is disabled. Without this guard, builds with localization disabled that happen to include could be broken because they would try to include <__locale>, which ends up trying to include the locale base API and eventually platform headers like <xlocale.h> that may not exist.

[llvmbot]

@llvm/pr-subscribers-libcxx

Author: Louis Dionne (ldionne)

Changes

The codecvt class is defined in <locale> and the contents of the <codecvt> header don't work when localization is disabled. Without this guard, builds with localization disabled that happen to include <codecvt> could be broken because they would try to include <__locale>, which ends up trying to include the locale base API and eventually platform headers like <xlocale.h> that may not exist.

---

Full diff: https://github.com/llvm/llvm-project/pull/129112.diff

1 Files Affected:

• (modified) libcxx/include/codecvt (+18-13)

diff --git a/libcxx/include/codecvt b/libcxx/include/codecvt
index f7ae804c6789c..0526b8512175f 100644
--- a/libcxx/include/codecvt
+++ b/libcxx/include/codecvt
@@ -58,14 +58,17 @@ class codecvt_utf8_utf16
 #  include <__cxx03/codecvt>
 #else
 #  include <__config>
-#  include <__locale>
-#  include <version>
 
-#  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#    pragma GCC system_header
-#  endif
+#  if _LIBCPP_HAS_LOCALIZATION
+
+#    include <__locale>
+#    include <version>
 
-#  if _LIBCPP_STD_VER < 26 || defined(_LIBCPP_BUILDING_LIBRARY) || defined(_LIBCPP_ENABLE_CXX26_REMOVED_CODECVT)
+#    if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#      pragma GCC system_header
+#    endif
+
+#    if _LIBCPP_STD_VER < 26 || defined(_LIBCPP_BUILDING_LIBRARY) || defined(_LIBCPP_ENABLE_CXX26_REMOVED_CODECVT)
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
@@ -76,7 +79,7 @@ enum _LIBCPP_DEPRECATED_IN_CXX17 codecvt_mode { consume_header = 4, generate_hea
 template <class _Elem>
 class __codecvt_utf8;
 
-#    if _LIBCPP_HAS_WIDE_CHARACTERS
+#      if _LIBCPP_HAS_WIDE_CHARACTERS
 template <>
 class _LIBCPP_EXPORTED_FROM_ABI __codecvt_utf8<wchar_t> : public codecvt<wchar_t, char, mbstate_t> {
   unsigned long __maxcode_;
@@ -115,7 +118,7 @@ protected:
   int do_length(state_type&, const extern_type* __frm, const extern_type* __end, size_t __mx) const override;
   int do_max_length() const _NOEXCEPT override;
 };
-#    endif // _LIBCPP_HAS_WIDE_CHARACTERS
+#      endif // _LIBCPP_HAS_WIDE_CHARACTERS
 
 _LIBCPP_SUPPRESS_DEPRECATED_PUSH
 template <>
@@ -206,7 +209,7 @@ _LIBCPP_SUPPRESS_DEPRECATED_POP
 template <class _Elem, bool _LittleEndian>
 class __codecvt_utf16;
 
-#    if _LIBCPP_HAS_WIDE_CHARACTERS
+#      if _LIBCPP_HAS_WIDE_CHARACTERS
 template <>
 class _LIBCPP_EXPORTED_FROM_ABI __codecvt_utf16<wchar_t, false> : public codecvt<wchar_t, char, mbstate_t> {
   unsigned long __maxcode_;
@@ -284,7 +287,7 @@ protected:
   int do_length(state_type&, const extern_type* __frm, const extern_type* __end, size_t __mx) const override;
   int do_max_length() const _NOEXCEPT override;
 };
-#    endif // _LIBCPP_HAS_WIDE_CHARACTERS
+#      endif // _LIBCPP_HAS_WIDE_CHARACTERS
 
 _LIBCPP_SUPPRESS_DEPRECATED_PUSH
 template <>
@@ -451,7 +454,7 @@ _LIBCPP_SUPPRESS_DEPRECATED_POP
 template <class _Elem>
 class __codecvt_utf8_utf16;
 
-#    if _LIBCPP_HAS_WIDE_CHARACTERS
+#      if _LIBCPP_HAS_WIDE_CHARACTERS
 template <>
 class _LIBCPP_EXPORTED_FROM_ABI __codecvt_utf8_utf16<wchar_t> : public codecvt<wchar_t, char, mbstate_t> {
   unsigned long __maxcode_;
@@ -490,7 +493,7 @@ protected:
   int do_length(state_type&, const extern_type* __frm, const extern_type* __end, size_t __mx) const override;
   int do_max_length() const _NOEXCEPT override;
 };
-#    endif // _LIBCPP_HAS_WIDE_CHARACTERS
+#      endif // _LIBCPP_HAS_WIDE_CHARACTERS
 
 _LIBCPP_SUPPRESS_DEPRECATED_PUSH
 template <>
@@ -579,7 +582,9 @@ _LIBCPP_SUPPRESS_DEPRECATED_POP
 
 _LIBCPP_END_NAMESPACE_STD
 
-#  endif // _LIBCPP_STD_VER < 26 || defined(_LIBCPP_BUILDING_LIBRARY) || defined(_LIBCPP_ENABLE_CXX26_REMOVED_CODECVT)
+#    endif // _LIBCPP_STD_VER < 26 || defined(_LIBCPP_BUILDING_LIBRARY) || defined(_LIBCPP_ENABLE_CXX26_REMOVED_CODECVT)
+
+#  endif // _LIBCPP_HAS_LOCALIZATION
 
 #  if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
 #    include <atomic>

[philnik777]

I feel like we need a better story for this kind of exclusion. It's getting quite viral. But I guess it's fine for now.

[ldionne]

I feel like we need a better story for this kind of exclusion. It's getting quite viral. But I guess it's fine for now.

I agree. I am working on actually removing most of the locale-based exclusion. By formalizing the locale base API, my hope is that the "no localization" setting can instead be a "emulate only the C locale" setting, which would allow us to provide regex, iostreams and more in the "no localization" setup, but without being able to actually switch to another locale than C.

[ldionne]

@philnik777 I think your recent patch about std::async has issues on FreeBSD -- likely another race condition with the re-enablement of the CI job. Can you have a look? I'm about to go OOO for a bit and I won't have time to look into that one.

[ldionne]

Either way, that failure isn't related to this change so I'm going ahead with merging this.

[ldionne]

/cherry-pick fda7373

[llvmbot]

/pull-request #129305