[libcxx] Add availability for populating cache from directory_iterator.

Author: ed-sat

libcxx/include/__configuration/availability.h

@@ -353,6 +353,12 @@
 #define _LIBCPP_AVAILABILITY_HAS_BAD_EXPECTED_ACCESS_KEY_FUNCTION _LIBCPP_INTRODUCED_IN_LLVM_19
 #define _LIBCPP_AVAILABILITY_BAD_EXPECTED_ACCESS_KEY_FUNCTION _LIBCPP_INTRODUCED_IN_LLVM_19_ATTRIBUTE
 
+// This controls the availability of populating cache for directory entry
+// filesystem system. A directory_iterator builds cache for directory_entry
+// in the library.
+#define _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_FULLY_POPULATED_CACHED_ENTRY _LIBCPP_INTRODUCED_IN_LLVM_19
+#define _LIBCPP_AVAILABILITY_FILESYSTEM_FULLY_POPULATED_CACHED_ENTRY _LIBCPP_INTRODUCED_IN_LLVM_19_ATTRIBUTE
+
 // Define availability attributes that depend on _LIBCPP_HAS_NO_EXCEPTIONS.
 // Those are defined in terms of the availability attributes above, and
 // should not be vendor-specific.

libcxx/include/__filesystem/directory_entry.h

@@ -199,11 +199,13 @@ class directory_entry {
     _Empty,
     _IterSymlink,
     _IterNonSymlink,
-    _IterCachedSymlink,
-    _IterCachedNonSymlink,
     _RefreshSymlink,
     _RefreshSymlinkUnresolved,
-    _RefreshNonSymlink
+    _RefreshNonSymlink,
+#  if _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_FULLY_POPULATED_CACHED_ENTRY
+    _IterCachedSymlink,
+    _IterCachedNonSymlink
+#  endif // _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_FULLY_POPULATED_CACHED_ENTRY
   };
 
   struct __cached_data {
@@ -242,6 +244,7 @@ class directory_entry {
     return __data;
   }
 
+  _LIBCPP_AVAILABILITY_FILESYSTEM_FULLY_POPULATED_CACHED_ENTRY
   _LIBCPP_HIDE_FROM_ABI static __cached_data
   __create_iter_cached_result(file_type __ft, uintmax_t __size, perms __perm, file_time_type __write_time) {
     __cached_data __data;
@@ -306,34 +309,42 @@ class directory_entry {
     case _Empty:
       return __symlink_status(__p_, __ec).type();
     case _IterSymlink:
+#  if _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_FULLY_POPULATED_CACHED_ENTRY
     case _IterCachedSymlink:
+#  endif // _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_FULLY_POPULATED_CACHED_ENTRY
     case _RefreshSymlink:
     case _RefreshSymlinkUnresolved:
       if (__ec)
         __ec->clear();
       return file_type::symlink;
-    case _IterNonSymlink:
+#  if _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_FULLY_POPULATED_CACHED_ENTRY
     case _IterCachedNonSymlink:
-    case _RefreshNonSymlink:
+#  endif // _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_FULLY_POPULATED_CACHED_ENTRY
+    case _IterNonSymlink:
+    case _RefreshNonSymlink: {
       file_status __st(__data_.__type_);
       if (__ec && !filesystem::exists(__st))
         *__ec = make_error_code(errc::no_such_file_or_directory);
       else if (__ec)
         __ec->clear();
       return __data_.__type_;
     }
+    }
     __libcpp_unreachable();
   }
 
   _LIBCPP_HIDE_FROM_ABI file_type __get_ft(error_code* __ec = nullptr) const {
     switch (__data_.__cache_type_) {
     case _Empty:
     case _IterSymlink:
-    case _IterCachedSymlink:
     case _RefreshSymlinkUnresolved:
       return __status(__p_, __ec).type();
-    case _IterNonSymlink:
+#  if _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_FULLY_POPULATED_CACHED_ENTRY
+    case _IterCachedSymlink:
+      return __status(__p_, __ec).type();
     case _IterCachedNonSymlink:
+#  endif // _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_FULLY_POPULATED_CACHED_ENTRY
+    case _IterNonSymlink:
     case _RefreshNonSymlink:
     case _RefreshSymlink: {
       file_status __st(__data_.__type_);
@@ -352,13 +363,17 @@ class directory_entry {
     case _Empty:
     case _IterNonSymlink:
     case _IterSymlink:
-    case _IterCachedSymlink:
     case _RefreshSymlinkUnresolved:
       return __status(__p_, __ec);
-    case _IterCachedNonSymlink:
     case _RefreshNonSymlink:
     case _RefreshSymlink:
       return file_status(__get_ft(__ec), __data_.__non_sym_perms_);
+#    if _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_FULLY_POPULATED_CACHED_ENTRY
+    case _IterCachedSymlink:
+      return __status(__p_, __ec);
+    case _IterCachedNonSymlink:
+      return file_status(__get_ft(__ec), __data_.__non_sym_perms_);
+#    endif // _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_FULLY_POPULATED_CACHED_ENTRY
     }
     __libcpp_unreachable();
   }
@@ -369,13 +384,17 @@ class directory_entry {
     case _IterNonSymlink:
     case _IterSymlink:
       return __symlink_status(__p_, __ec);
-    case _IterCachedNonSymlink:
     case _RefreshNonSymlink:
       return file_status(__get_sym_ft(__ec), __data_.__non_sym_perms_);
-    case _IterCachedSymlink:
     case _RefreshSymlink:
     case _RefreshSymlinkUnresolved:
       return file_status(__get_sym_ft(__ec), __data_.__sym_perms_);
+#    if _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_FULLY_POPULATED_CACHED_ENTRY
+    case _IterCachedNonSymlink:
+      return file_status(__get_sym_ft(__ec), __data_.__non_sym_perms_);
+    case _IterCachedSymlink:
+      return file_status(__get_sym_ft(__ec), __data_.__sym_perms_);
+#    endif // _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_FULLY_POPULATED_CACHED_ENTRY
     }
     __libcpp_unreachable();
   }
@@ -385,10 +404,13 @@ class directory_entry {
     case _Empty:
     case _IterNonSymlink:
     case _IterSymlink:
-    case _IterCachedSymlink:
     case _RefreshSymlinkUnresolved:
       return filesystem::__file_size(__p_, __ec);
+#  if _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_FULLY_POPULATED_CACHED_ENTRY
+    case _IterCachedSymlink:
+      return filesystem::__file_size(__p_, __ec);
     case _IterCachedNonSymlink:
+#  endif // _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_FULLY_POPULATED_CACHED_ENTRY
     case _RefreshSymlink:
     case _RefreshNonSymlink: {
       error_code __m_ec;
@@ -409,8 +431,10 @@ class directory_entry {
     case _Empty:
     case _IterNonSymlink:
     case _IterSymlink:
+#  if _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_FULLY_POPULATED_CACHED_ENTRY
     case _IterCachedNonSymlink:
     case _IterCachedSymlink:
+#  endif // _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_FULLY_POPULATED_CACHED_ENTRY
     case _RefreshSymlinkUnresolved:
       return filesystem::__hard_link_count(__p_, __ec);
     case _RefreshSymlink:
@@ -429,10 +453,13 @@ class directory_entry {
     case _Empty:
     case _IterNonSymlink:
     case _IterSymlink:
-    case _IterCachedSymlink:
     case _RefreshSymlinkUnresolved:
       return filesystem::__last_write_time(__p_, __ec);
+#  if _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_FULLY_POPULATED_CACHED_ENTRY
+    case _IterCachedSymlink:
+      return filesystem::__last_write_time(__p_, __ec);
     case _IterCachedNonSymlink:
+#  endif // _LIBCPP_AVAILABILITY_HAS_FILESYSTEM_FULLY_POPULATED_CACHED_ENTRY
     case _RefreshSymlink:
     case _RefreshNonSymlink: {
       error_code __m_ec;