Add LLVM 22 availability annotation

Author: smallp-o-p

libcxx/include/__configuration/availability.h

@@ -84,6 +84,9 @@
 // in all versions of the library are available.
 #if !_LIBCPP_HAS_VENDOR_AVAILABILITY_ANNOTATIONS
 
+#  define _LIBCPP_INTRODUCED_IN_LLVM_22 1
+#  define _LIBCPP_INTRODUCED_IN_LLVM_22_ATTRIBUTE /* nothing */
+
 #  define _LIBCPP_INTRODUCED_IN_LLVM_21 1
 #  define _LIBCPP_INTRODUCED_IN_LLVM_21_ATTRIBUTE /* nothing */
 
@@ -112,6 +115,10 @@
 
 // clang-format off
 
+// LLVM 22 
+#  define _LIBCPP_INTRODUCED_IN_LLVM_22 0
+#  define _LIBCPP_INTRODUCED_IN_LLVM_22_ATTRIBUTE __attribute__((unavailable))
+
 // LLVM 21
 // TODO: Fill this in
 #  define _LIBCPP_INTRODUCED_IN_LLVM_21 0
@@ -291,6 +298,10 @@
 #define _LIBCPP_AVAILABILITY_HAS_BAD_FUNCTION_CALL_GOOD_WHAT_MESSAGE _LIBCPP_INTRODUCED_IN_LLVM_21
 // No attribute, since we've had bad_function_call::what() in the headers before
 
+// Controls whether the internal implementation for text_encoding::environment() -> te_impl::__environment() is available
+#define _LIBCPP_AVAILABILITY_HAS_TE_ENVIRONMENT _LIBCPP_INTRODUCED_IN_LLVM_22
+#define _LIBCPP_AVAILABILITY_TE_ENVIRONMENT _LIBCPP_INTRODUCED_IN_LLVM_22_ATTRIBUTE
+
 // Define availability attributes that depend on both
 // _LIBCPP_HAS_EXCEPTIONS and _LIBCPP_HAS_RTTI.
 #if !_LIBCPP_HAS_EXCEPTIONS || !_LIBCPP_HAS_RTTI

libcxx/include/__text_encoding/te_impl.h

@@ -531,12 +531,14 @@ struct __te_impl {
   _LIBCPP_HIDDEN static __id __get_win32_acp();
 #    endif
 
+#    if _LIBCPP_AVAILABILITY_HAS_TE_ENVIRONMENT
   [[nodiscard]] _LIBCPP_EXPORTED_FROM_ABI static __te_impl __environment();
 
   template <__id _Id>
   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI static bool __environment_is() {
     return __environment() == _Id;
   }
+#    endif
 #  endif
 
   const __te_data* __encoding_rep_     = __text_encoding_data + 1;

libcxx/test/libcxx/utilities/text_encoding/environment.pass.cpp

@@ -14,6 +14,7 @@
 // UNSUPPORTED: no-localization
 // UNSUPPORTED: android
 // UNSUPPORTED: windows
+// UNSUPPORTED: availability-te-environment-missing
 
 #include <algorithm>
 #include <cassert>

libcxx/test/std/utilities/text_encoding/text_encoding.members/environment.pass.cpp

@@ -13,6 +13,7 @@
 
 // UNSUPPORTED: no-localization
 // UNSUPPORTED: android
+// UNSUPPORTED: availability-te-environment-missing
 
 // class text_encoding
 

libcxx/utils/libcxx/test/features.py

@@ -889,4 +889,13 @@ def check_gdb(cfg):
             cfg.available_features,
         ),
     ),
+    
+    # Tests that require std::text_encoding::environment() in the built library
+    Feature(
+        name="availability-te-environment-missing",
+        when=lambda cfg: BooleanExpression.evaluate(
+            "!libcpp-has-no-availability-markup && (stdlib=apple-libc++ && !_target-has-llvm-22)",
+            cfg.available_features,
+        ),
+    ),
 ]