[libcxx-commits] [libcxx] [libc++][streams] P1759R6: Native handles and file streams (PR #76632)

[Mark de Wever via libcxx-commits]

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@@ -0,0 +1,60 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef TEST_STD_INPUT_OUTPUT_FILE_STREAMS_FSTREAMS_TEST_HELPERS_H
+#define TEST_STD_INPUT_OUTPUT_FILE_STREAMS_FSTREAMS_TEST_HELPERS_H
+
+#if _LIBCPP_STD_VER >= 26
+
+#  include <cassert>
+#  include <cstdio>
+#  include <fstream>
+#  include <filesystem>
+#  include <utility>
+
+#  if defined(_LIBCPP_WIN32API)
+#    define WIN32_LEAN_AND_MEAN
+#    define NOMINMAX
+#    include <io.h>
+#    include <windows.h>
+#  else
+#    include <fcntl.h>
+#  endif
+
+#  include "platform_support.h"
+
+#  if defined(_LIBCPP_WIN32API)
+auto is_handle_valid([[maybe_unused]] HANDLE handle) {
+  // TODO: Maybe test HANDLE with GetFileInformationByHandle??
+  return true;
+};
+#  else
+// POSIX
+auto is_handle_valid(int fd) { return fcntl(fd, F_GETFL) != -1 || errno != EBADF; };
+#  endif
+
+template <typename CharT, typename StreamT>
+void test_native_handle() {
+  static_assert(
+      std::is_same_v<typename std::basic_filebuf<CharT>::native_handle_type, typename StreamT::native_handle_type>);
+
+  StreamT f;
+  static_assert(noexcept(f.native_handle()));
+  assert(!f.is_open());
+  std::filesystem::path p = get_temp_file_name();
+  f.open(p);
+  assert(f.is_open());
+  assert(f.native_handle() == f.rdbuf()->native_handle());
+  assert(is_handle_valid(f.native_handle()));
+  assert(is_handle_valid(std::as_const(f).native_handle()));
+  static_assert(noexcept(f.native_handle()));
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mordante wrote:

let's test this for the `as_const(f)` too. In theory we can have a non-const overload that is correct.

I would also group the const and non-const tests.

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