[libc++][print] Adds ostream overloads. (#73262)

Finishes implementation of
- P2093R14 Formatted output
- P2539R4 Should the output of std::print to a terminal be synchronized
with the underlying stream?

Differential Revision: https://reviews.llvm.org/D156609

3 files changed, 45 insertions, 0 deletions

diff --git a/libcxx/src/CMakeLists.txt b/libcxx/src/CMakeLists.txt
index be0113e..329964a 100644
--- a/libcxx/src/CMakeLists.txt
+++ b/libcxx/src/CMakeLists.txt
@@ -89,6 +89,7 @@ if (LIBCXX_ENABLE_LOCALIZATION)
     ios.instantiations.cpp
     iostream.cpp
     locale.cpp
+    ostream.cpp
     regex.cpp
     strstream.cpp
     )
diff --git a/libcxx/src/ostream.cpp b/libcxx/src/ostream.cpp
new file mode 100644
index 0000000..bba8e65
--- /dev/null
+++ b/libcxx/src/ostream.cpp
@@ -0,0 +1,42 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include <__availability>
+#include <__config>
+#ifndef _LIBCPP_HAS_NO_FILESYSTEM
+#  include <fstream>
+#endif
+#include <ostream>
+
+#include "std_stream.h"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+_LIBCPP_AVAILABILITY_PRINT _LIBCPP_EXPORTED_FROM_ABI FILE* __get_ostream_file(ostream& __os) {
+  // dynamic_cast requires RTTI, this only affects users whose vendor builds
+  // the dylib with RTTI disabled. It does not affect users who build with RTTI
+  // disabled but use a dylib where the RTTI is enabled.
+  //
+  // Returning a nullptr means the stream is not considered a terminal and the
+  // special terminal handling is not done. The terminal handling is mainly of
+  // importance on Windows.
+#ifndef _LIBCPP_HAS_NO_RTTI
+  auto* __rdbuf = __os.rdbuf();
+#  ifndef _LIBCPP_HAS_NO_FILESYSTEM
+  if (auto* __buffer = dynamic_cast<filebuf*>(__rdbuf))
+    return __buffer->__file_;
+#  endif
+
+  if (auto* __buffer = dynamic_cast<__stdoutbuf<char>*>(__rdbuf))
+    return __buffer->__file_;
+#endif // _LIBCPP_HAS_NO_RTTI
+
+  return nullptr;
+}
+
+_LIBCPP_END_NAMESPACE_STD
diff --git a/libcxx/src/std_stream.h b/libcxx/src/std_stream.h
index c4e9733..e55cd0b 100644
--- a/libcxx/src/std_stream.h
+++ b/libcxx/src/std_stream.h
@@ -269,6 +269,8 @@ private:
 
   __stdoutbuf(const __stdoutbuf&);
   __stdoutbuf& operator=(const __stdoutbuf&);
+
+  _LIBCPP_EXPORTED_FROM_ABI friend FILE* __get_ostream_file(ostream&);
 };
 
 template <class _CharT>