Import libc++ 8.0.0.

4 files changed, 84 insertions, 49 deletions

diff --git a/lib/libcxx/docs/DesignDocs/AvailabilityMarkup.rst b/lib/libcxx/docs/DesignDocs/AvailabilityMarkup.rst
index b8b44509790..4e6d80b50bf 100644
--- a/lib/libcxx/docs/DesignDocs/AvailabilityMarkup.rst
+++ b/lib/libcxx/docs/DesignDocs/AvailabilityMarkup.rst
@@ -24,11 +24,11 @@ systems. For example::
 
     // Define availability macros.
     #if defined(_LIBCPP_USE_AVAILABILITY_APPLE)
-    #define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS __attribute__((unavailable))
+    # define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS __attribute__((unavailable))
     #else  if defined(_LIBCPP_USE_AVAILABILITY_SOME_OTHER_VENDOR)
-    #define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS __attribute__((unavailable))
-	#else
-    #define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS
+    # define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS __attribute__((unavailable))
+    #else
+    # define _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS
     #endif
 
 When the library is updated by the platform vendor, the markup can be updated.
@@ -43,9 +43,9 @@ For example::
 In the source code, the macro can be added on a class if the full class requires
 type info from the library for example::
 
-	_LIBCPP_BEGIN_NAMESPACE_EXPERIMENTAL
-	class _LIBCPP_EXCEPTION_ABI _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS bad_optional_access
-	    : public std::logic_error {
+    _LIBCPP_BEGIN_NAMESPACE_EXPERIMENTAL
+    class _LIBCPP_EXCEPTION_ABI _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS bad_optional_access
+      : public std::logic_error {
 
 or on a particular symbol:
 
@@ -55,7 +55,7 @@ or on a particular symbol:
 Testing
 =======
 
-Some parameters can be passed to lit to run the test-suite and exercising the
+Some parameters can be passed to lit to run the test-suite and exercise the
 availability.
 
 * The `platform` parameter controls the deployment target. For example lit can
@@ -65,14 +65,11 @@ availability.
   the test-suite against the host system library. Alternatively a path to the
   directory containing a specific prebuilt libc++ can be used, for example:
   `--param=use_system_cxx_lib=/path/to/macOS/10.8/`.
-* The `with_availability` boolean parameter enables the availability markup.
 
 Tests can be marked as XFAIL based on multiple features made available by lit:
 
 
-* if either `use_system_cxx_lib` or  `with_availability` is passed to lit,
-  assuming `--param=platform=macosx10.8` is passed as well the following
-  features will be available:
+* if `--param=platform=macosx10.8` is passed, the following features will be available:
 
   - availability
   - availability=x86_64
@@ -81,11 +78,11 @@ Tests can be marked as XFAIL based on multiple features made available by lit:
   - availability=x86_64-apple-macosx10.8
   - availability=macosx10.8
 
-  This feature is used to XFAIL a test that *is* using a class of a method marked
+  This feature is used to XFAIL a test that *is* using a class or a method marked
   as unavailable *and* that is expected to *fail* if deployed on an older system.
 
-* if `use_system_cxx_lib` is passed to lit, the following features will also
-  be available:
+* if `use_system_cxx_lib` and `--param=platform=macosx10.8` are passed to lit,
+  the following features will also be available:
 
   - with_system_cxx_lib
   - with_system_cxx_lib=x86_64
@@ -94,21 +91,9 @@ Tests can be marked as XFAIL based on multiple features made available by lit:
   - with_system_cxx_lib=x86_64-apple-macosx10.8
   - with_system_cxx_lib=macosx10.8
 
-  This feature is used to XFAIL a test that is *not* using a class of a method
+  This feature is used to XFAIL a test that is *not* using a class or a method
   marked as unavailable *but* that is expected to fail if deployed on an older
-  system. For example if we know that it exhibits a but in the libc on a
-  particular system version.
-
-* if `with_availability` is passed to lit, the following features will also
-  be available:
-
-  - availability_markup
-  - availability_markup=x86_64
-  - availability_markup=macosx
-  - availability_markup=x86_64-macosx
-  - availability_markup=x86_64-apple-macosx10.8
-  - availability_markup=macosx10.8
-
-  This feature is used to XFAIL a test that *is* using a class of a method
-  marked as unavailable *but* that is expected to *pass* if deployed on an older
-  system. For example if it is using a symbol in a statically evaluated context.
+  system. For example, if the test exhibits a bug in the libc on a particular
+  system version, or if the test uses a symbol that is not available on an
+  older version of the dylib (but for which there is no availability markup,
+  otherwise the XFAIL should use `availability` above).
diff --git a/lib/libcxx/docs/DesignDocs/CapturingConfigInfo.rst b/lib/libcxx/docs/DesignDocs/CapturingConfigInfo.rst
index 88102251d93..29156bff8bc 100644
--- a/lib/libcxx/docs/DesignDocs/CapturingConfigInfo.rst
+++ b/lib/libcxx/docs/DesignDocs/CapturingConfigInfo.rst
@@ -28,7 +28,7 @@ Design Goals
   It makes developers lives harder if they have to regenerate the libc++ headers
   every time they are modified.
 
-* The solution should not make any of the libc++ headers dependant on
+* The solution should not make any of the libc++ headers dependent on
   files generated by the build system. The headers should be able to compile
   out of the box without any modification.
 
diff --git a/lib/libcxx/docs/DesignDocs/FeatureTestMacros.rst b/lib/libcxx/docs/DesignDocs/FeatureTestMacros.rst
new file mode 100644
index 00000000000..d55af96c674
--- /dev/null
+++ b/lib/libcxx/docs/DesignDocs/FeatureTestMacros.rst
@@ -0,0 +1,44 @@
+===================
+Feature Test Macros
+===================
+
+.. contents::
+   :local:
+
+Overview
+========
+
+Libc++ implements the C++ feature test macros as specified in the C++2a standard,
+and before that in non-normative guiding documents (`See cppreference <https://en.cppreference.com/w/User:D41D8CD98F/feature_testing_macros>`)
+
+Design
+======
+
+Feature test macros are tricky to track, implement, test, and document correctly.
+They must be available from a list of headers, they may have different values in
+different dialects, and they may or may not be implemented by libc++. In order to
+track all of these conditions correctly and easily, we want a Single Source of
+Truth (SSoT) that defines each feature test macro, its values, the headers it
+lives in, and whether or not is is implemented by libc++. From this SSoA we
+have enough information to automatically generate the `<version>` header,
+the tests, and the documentation.
+
+Therefore we maintain a SSoA in
+`libcxx/test/std/language.support/support.limits/support.limits.general/generate_feature_test_macro_components.py`
+which doubles as a script to generate the following components:
+
+* The `<version>` header.
+* The version tests under `support.limits.general`.
+* Documentation of libc++'s implementation of each macro.
+
+Usage
+=====
+
+The `generate_feature_test_macro_components.py` script is used to track and
+update feature test macros in libc++.
+
+Whenever a feature test macro is added or changed, the table should be updated
+and the script should be re-ran. The script will clobber the existing test files
+and the documentation and it will generate a new `<version>` header as a
+temporary file. The generated `<version>` header should be merged with the
+existing one.
\ No newline at end of file
diff --git a/lib/libcxx/docs/DesignDocs/VisibilityMacros.rst b/lib/libcxx/docs/DesignDocs/VisibilityMacros.rst
index ab577df1364..d0d4f0adb22 100644
--- a/lib/libcxx/docs/DesignDocs/VisibilityMacros.rst
+++ b/lib/libcxx/docs/DesignDocs/VisibilityMacros.rst
@@ -22,11 +22,11 @@ Visibility Macros
   Mark a symbol as being exported by the libc++ library. This attribute must
   be applied to the declaration of all functions exported by the libc++ dylib.
 
-**_LIBCPP_EXTERN_VIS**
+**_LIBCPP_EXPORTED_FROM_ABI**
   Mark a symbol as being exported by the libc++ library. This attribute may
-  only be applied to objects defined in the libc++ library. On Windows this
-  macro applies `dllimport`/`dllexport` to the symbol. On all other platforms
-  this macro has no effect.
+  only be applied to objects defined in the libc++ runtime library. On Windows,
+  this macro applies `dllimport`/`dllexport` to the symbol, and on other
+  platforms it gives the symbol default visibility.
 
 **_LIBCPP_OVERRIDABLE_FUNC_VIS**
   Mark a symbol as being exported by the libc++ library, but allow it to be
@@ -44,6 +44,21 @@ Visibility Macros
   Mark a function as not being part of the ABI of any final linked image that
   uses it.
 
+**_LIBCPP_HIDE_FROM_ABI_AFTER_V1**
+  Mark a function as being hidden from the ABI (per `_LIBCPP_HIDE_FROM_ABI`)
+  when libc++ is built with an ABI version after ABI v1. This macro is used to
+  maintain ABI compatibility for symbols that have been historically exported
+  by libc++ in v1 of the ABI, but that we don't want to export in the future.
+
+  This macro works as follows. When we build libc++, we either hide the symbol
+  from the ABI (if the symbol is not part of the ABI in the version we're
+  building), or we leave it included. From user code (i.e. when we're not
+  building libc++), the macro always marks symbols as internal so that programs
+  built using new libc++ headers stop relying on symbols that are removed from
+  the ABI in a future version. Each time we release a new stable version of the
+  ABI, we should create a new _LIBCPP_HIDE_FROM_ABI_AFTER_XXX macro, and we can
+  use it to start removing symbols from the ABI after that stable version.
+
 **_LIBCPP_HIDE_FROM_ABI_PER_TU**
   This macro controls whether symbols hidden from the ABI with `_LIBCPP_HIDE_FROM_ABI`
   are local to each translation unit in addition to being local to each final
@@ -67,9 +82,9 @@ Visibility Macros
 **_LIBCPP_HIDE_FROM_ABI_PER_TU_BY_DEFAULT**
   This macro controls the default value for `_LIBCPP_HIDE_FROM_ABI_PER_TU`.
   When the macro is defined, per TU ABI insulation is enabled by default, and
-  `_LIBCPP_HIDE_FROM_ABI_PER_TU` is defined to 1 unless overriden by users.
+  `_LIBCPP_HIDE_FROM_ABI_PER_TU` is defined to 1 unless overridden by users.
   Otherwise, per TU ABI insulation is disabled by default, and
-  `_LIBCPP_HIDE_FROM_ABI_PER_TU` is defined to 0 unless overriden by users.
+  `_LIBCPP_HIDE_FROM_ABI_PER_TU` is defined to 0 unless overridden by users.
 
   This macro is intended for vendors to control whether they want to ship
   libc++ with per TU ABI insulation enabled by default. Users can always
@@ -77,7 +92,7 @@ Visibility Macros
   appropriately.
 
   By default, this macro is not defined, which means that per TU ABI insulation
-  is not provided unless explicitly overriden by users.
+  is not provided unless explicitly overridden by users.
 
 **_LIBCPP_TYPE_VIS**
   Mark a type's typeinfo, vtable and members as having default visibility.
@@ -172,15 +187,6 @@ Visibility Macros
   against the libc++ headers after making `_LIBCPP_TYPE_VIS` and
   `_LIBCPP_EXTERN_TEMPLATE_TYPE_VIS` expand to default visibility.
 
-**_LIBCPP_EXTERN_TEMPLATE_INLINE_VISIBILITY**
-  Mark a member function of a class template as visible and always inline. This
-  macro should only be applied to member functions of class templates that are
-  externally instantiated. It is important that these symbols are not marked
-  as hidden as that will prevent the dylib definition from being found.
-
-  This macro is used to maintain ABI compatibility for symbols that have been
-  historically exported by the libc++ library but are now marked inline.
-
 **_LIBCPP_EXCEPTION_ABI**
   Mark the member functions, typeinfo, and vtable of the type as being exported
   by the libc++ library. This macro must be applied to all *exception types*.