[llvm] [clang] [lld] [libcxx] [flang] [libc++][streams] P1759R6: Native handles and file streams (PR #76632)

[Hristo Hristov via cfe-commits]

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@@ -245,6 +267,18 @@ public:
 #  endif
   _LIBCPP_HIDE_FROM_ABI basic_filebuf* __open(int __fd, ios_base::openmode __mode);
   basic_filebuf* close();
+#  if _LIBCPP_STD_VER >= 26
+  _LIBCPP_HIDE_FROM_ABI native_handle_type native_handle() const noexcept {
+    _LIBCPP_ASSERT_UNCATEGORIZED(this->is_open(), "File must be opened");
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H-G-Hristov wrote:

Can runtime assertions be validated? I couldn't figure it out.

https://github.com/llvm/llvm-project/pull/76632