[libcxx-commits] [libcxx] [libc++] Optimize ofstream::write (PR #123337)

[Louis Dionne via libcxx-commits]

================
@@ -0,0 +1,43 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_DISABLE_DEPRECATION_WARNINGS
+
+// <fstream>
+
+#include <cassert>
+#include <fstream>
+#include <vector>
+
+#include "test_macros.h"
+
+void sputn_not_open() {
+    std::vector<char> data(10, 'a');
+    std::filebuf f;
+    std::streamsize len = f.sputn(data.data(), data.size());
+    assert(len == 0);
+    assert(std::strncmp(data.data(), "aaaaaaaaaa", 10) == 0);
+}
+
+#ifndef TEST_HAS_NO_WIDE_CHARACTERS
+void sputn_not_open_wchar() {
+    std::vector<wchar_t> data(10, L'a');
+    std::wfilebuf f;
+    std::streamsize len = f.sputn(data.data(), data.size());
+    assert(len == 0);
+    assert(std::wcsncmp(data.data(), L"aaaaaaaaaa", 10) == 0);
+}
+#endif
+
+int main(int, char **) {
+    sputn_not_open();
+#ifndef TEST_HAS_NO_WIDE_CHARACTERS
+    sputn_not_open_wchar();
+#endif
+    return 0;
+}
----------------
ldionne wrote:

Newline!

https://github.com/llvm/llvm-project/pull/123337