[libcxx-commits] [PATCH] D129054: [libc++] Consolidate the different [[nodiscard]] configuration options into a single one

[Nikolas Klauser via Phabricator via libcxx-commits]

philnik created this revision.
philnik added reviewers: ldionne, Mordante, var-const.
Herald added a project: All.
philnik requested review of this revision.
Herald added a project: libc++.
Herald added a subscriber: libcxx-commits.
Herald added a reviewer: libc++.

Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D129054

Files:
  libcxx/docs/ReleaseNotes.rst
  libcxx/include/__config


Index: libcxx/include/__config
===================================================================
--- libcxx/include/__config
+++ libcxx/include/__config
@@ -823,13 +823,13 @@
 
 // _LIBCPP_NODISCARD_EXT may be used to apply [[nodiscard]] to entities not
 // specified as such as an extension.
-#  if defined(_LIBCPP_ENABLE_NODISCARD) && !defined(_LIBCPP_DISABLE_NODISCARD_EXT)
+#  if defined (_LIBCPP_ENABLE_NODISCARD_EXT)
 #    define _LIBCPP_NODISCARD_EXT _LIBCPP_NODISCARD
 #  else
 #    define _LIBCPP_NODISCARD_EXT
 #  endif
 
-#  if !defined(_LIBCPP_DISABLE_NODISCARD_AFTER_CXX17) && (_LIBCPP_STD_VER > 17 || defined(_LIBCPP_ENABLE_NODISCARD))
+#  if _LIBCPP_STD_VER > 17 || defined(_LIBCPP_ENABLE_NODISCARD_EXT)
 #    define _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_NODISCARD
 #  else
 #    define _LIBCPP_NODISCARD_AFTER_CXX17
Index: libcxx/docs/ReleaseNotes.rst
===================================================================
--- libcxx/docs/ReleaseNotes.rst
+++ libcxx/docs/ReleaseNotes.rst
@@ -160,6 +160,11 @@
   To disable deprecation warnings you have to define ``_LIBCPP_DISABLE_DEPRECATION_WARNINGS``. Note that this
   disables all deprecation warnings.
 
+- ``_LIBCPP_ENABLE_NODISCARD`` and ``_LIBCPP_DISABLE_NODISCARD_AFTER_CXX17`` are no longer respected.
+  Any standards-required ``[[nodiscard]]`` applications in C++20 are now always enabled. Any extended applications
+  can now be enabled by defining ``_LIBCPP_ENABLE_NODISCARD_EXT``. Note that this also enables applications of
+  ``[[nodiscard]]`` in places where no version of the standard requires the attribute.
+
 ABI Changes
 -----------
 


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