[libc++] Treat incomplete features just like other experimental features

In particular remove the ability to expel incomplete features from the
library at configure-time, since this can now be done through the
_LIBCPP_ENABLE_EXPERIMENTAL macro.

Also, never provide symbols related to incomplete features inside the
dylib, instead provide them in c++experimental.a (this changes the
symbols list, but not for any configuration that should have shipped).

Differential Revision: https://reviews.llvm.org/D128928

3 files changed, 1 insertions, 104 deletions

diff --git a/libcxx/docs/BuildingLibcxx.rst b/libcxx/docs/BuildingLibcxx.rst
index 7c347c6..f365aac 100644
--- a/libcxx/docs/BuildingLibcxx.rst
+++ b/libcxx/docs/BuildingLibcxx.rst
@@ -265,15 +265,6 @@ libc++ specific options
    support for ``wchar_t``. This is especially useful in embedded settings where
    C Standard Libraries don't always provide all the usual bells and whistles.
 
-.. option:: LIBCXX_ENABLE_INCOMPLETE_FEATURES:BOOL
-
-  **Default**: ``ON``
-
-  Whether to enable support for incomplete library features. Incomplete features
-  are new library features under development. These features don't guarantee
-  ABI stability nor the quality of completed library features. Vendors
-  shipping the library may want to disable this option.
-
 .. option:: LIBCXX_INSTALL_LIBRARY_DIR:PATH
 
   **Default**: ``lib${LIBCXX_LIBDIR_SUFFIX}``
diff --git a/libcxx/docs/Contributing.rst b/libcxx/docs/Contributing.rst
index 9806f9b..15c75e8 100644
--- a/libcxx/docs/Contributing.rst
+++ b/libcxx/docs/Contributing.rst
@@ -86,97 +86,3 @@ abilist for the platform, e.g.:
 
 * C++20 for the Linux platform.
 * MacOS C++20 for the Apple platform.
-
-Working on large features
-=========================
-
-Libc++ makes no guarantees about the implementation status or the ABI stability
-of features that have not yet been ratified in the C++ Standard. After the C++
-Standard is ratified libc++ promises a conforming and ABI-stable
-implementation. When working on a large new feature in the ratified version of
-the C++ Standard that can't be finished before the next release branch is
-created, we can't honor this promise. Another reason for not being able to
-promise ABI stability happens when the C++ Standard committee retroactively
-accepts ABI breaking papers as defect reports against the ratified C++
-Standard.
-
-When working on these features it should be possible for libc++ vendors to
-disable these incomplete features, so they can promise ABI stability to their
-customers. This is done by the CMake option
-``LIBCXX_ENABLE_INCOMPLETE_FEATURES``. When start working on a large feature
-the following steps are required to guard the new library with the CMake
-option.
-
-* ``libcxx/CMakeLists.txt``: Add
-
-  .. code-block:: cmake
-
-    config_define_if_not(LIBCXX_ENABLE_INCOMPLETE_FEATURES _LIBCPP_HAS_NO_INCOMPLETE_FOO)
-
-* ``libcxx/include/__config_site.in``: Add
-
-  .. code-block:: c++
-
-    #cmakedefine _LIBCPP_HAS_NO_INCOMPLETE_FOO
-
-* ``libcxx/include/foo``: The contents of the file should be guarded in an
-  ``ifdef`` and always include ``<version>``
-
-  .. code-block:: c++
-
-    #ifndef _LIBCPP_FOO
-    #define _LIBCPP_FOO
-
-    // Make sure all feature-test macros are available.
-    #include <version>
-    // Enable the contents of the header only when libc++ was built with LIBCXX_ENABLE_INCOMPLETE_FEATURES.
-    #if !defined(_LIBCPP_HAS_NO_INCOMPLETE_FOO)
-
-    ...
-
-    #endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_FO0)
-    #endif // _LIBCPP_FOO
-
-* ``libcxx/src/CMakeLists.txt``: When the library has a file ``foo.cpp`` it
-  should only be added when ``LIBCXX_ENABLE_INCOMPLETE_FEATURES`` is enabled
-
-  .. code-block:: cmake
-
-    if(LIBCXX_ENABLE_INCOMPLETE_FEATURES)
-      list(APPEND LIBCXX_SOURCES
-        foo.cpp
-      )
-    endif()
-
-* ``libcxx/utils/generate_feature_test_macro_components.py``: Add to
-  ``lit_markup``
-
-  .. code-block:: python
-
-    "foo": ["UNSUPPORTED: libcpp-has-no-incomplete-foo"],
-
-* ``libcxx/utils/generate_header_inclusion_tests.py``: Add to ``lit_markup``
-
-  .. code-block:: python
-
-    "foo": ["UNSUPPORTED: libcpp-has-no-incomplete-foo"],
-
-* ``libcxx/utils/generate_header_tests.py``: Add to ``header_markup``
-
-  .. code-block:: python
-
-    "foo": ["ifndef _LIBCPP_HAS_NO_INCOMPLETE_FOO"],
-
-* ``libcxx/utils/libcxx/test/features.py``: Add to ``macros``
-
-  .. code-block:: python
-
-    '_LIBCPP_HAS_NO_INCOMPLETE_FOO': 'libcpp-has-no-incomplete-foo',
-
-* All tests that include ``<foo>`` should contain
-
-  .. code-block:: c++
-
-    // UNSUPPORTED: libcpp-has-no-incomplete-foo
-
-Once the library is complete these changes and guards should be removed.
diff --git a/libcxx/docs/Status/Cxx20.rst b/libcxx/docs/Status/Cxx20.rst
index e1a3c70..742d91a 100644
--- a/libcxx/docs/Status/Cxx20.rst
+++ b/libcxx/docs/Status/Cxx20.rst
@@ -42,7 +42,7 @@ Paper Status
 
    .. [#note-P0600] P0600: The missing bits in P0600 are in |sect|\ [mem.res.class] and |sect|\ [mem.poly.allocator.class].
    .. [#note-P0645] P0645: The paper is implemented but still marked as an incomplete feature
-      (the feature-test macro is not set and the libary is only available when built with ``LIBCXX_ENABLE_INCOMPLETE_FEATURES``).
+      (the feature-test macro is not set and the libary is only available when built with ``-D_LIBCPP_ENABLE_EXPERIMENTAL``).
       Not yet implemented LWG-issues will cause API and ABI breakage.
    .. [#note-P0966] P0966: It was previously erroneously marked as complete in version 8.0. See `bug 45368 <https://llvm.org/PR45368>`__.
    .. [#note-P0619] P0619: Only sections D.8, D.9, D.10 and D.13 are implemented. Sections D.4, D.7, D.11, D.12, and D.14 remain undone.