Vendor import of libc++ trunk r256633:vendor/libc++/r256633

https://llvm.org/svn/llvm-project/libcxx/trunk@256633

1 files changed, 263 insertions, 205 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 687c4cfc29a9..e6c96f64711b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,13 +3,16 @@
 #===============================================================================
 # Setup Project
 #===============================================================================
-
-project(libcxx CXX C)
 cmake_minimum_required(VERSION 2.8)
 
 if(POLICY CMP0042)
   cmake_policy(SET CMP0042 NEW) # Set MACOSX_RPATH=YES by default
 endif()
+if(POLICY CMP0022)
+  cmake_policy(SET CMP0022 NEW) # Required when interacting with LLVM and Clang
+endif()
+
+project(libcxx CXX C)
 
 set(PACKAGE_NAME libcxx)
 set(PACKAGE_VERSION trunk-svn)
@@ -30,61 +33,40 @@ MACRO_ENSURE_OUT_OF_SOURCE_BUILD(
  build directory and run 'cmake /path/to/${PROJECT_NAME} [options]' there."
  )
 
-if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
-  set(LIBCXX_LIBDIR_SUFFIX "" CACHE STRING
-      "Define suffix of library directory name (32/64)")
-
-  set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib${LIBCXX_LIBDIR_SUFFIX})
-  set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib${LIBCXX_LIBDIR_SUFFIX})
-
-  set(LIBCXX_BUILT_STANDALONE 1)
-else()
-  set(LIBCXX_LIBDIR_SUFFIX ${LLVM_LIBDIR_SUFFIX})
+# Find the LLVM sources and simulate LLVM CMake options.
+include(HandleOutOfTreeLLVM)
+if (LIBCXX_BUILT_STANDALONE AND NOT LLVM_FOUND)
+  message(WARNING "UNSUPPORTED LIBCXX CONFIGURATION DETECTED: "
+                  "llvm-config not found and LLVM_PATH not defined.\n"
+                  "Reconfigure with -DLLVM_CONFIG=path/to/llvm-config "
+                  "or -DLLVM_PATH=path/to/llvm-source-root.")
 endif()
 
 #===============================================================================
 # Setup CMake Options
 #===============================================================================
 
-# Define options.
-option(LIBCXX_ENABLE_EXCEPTIONS "Use exceptions." ON)
-option(LIBCXX_ENABLE_RTTI "Use run time type information." ON)
+# Basic options ---------------------------------------------------------------
 option(LIBCXX_ENABLE_ASSERTIONS "Enable assertions independent of build mode." ON)
-option(LIBCXX_ENABLE_PEDANTIC "Compile with pedantic enabled." ON)
-option(LIBCXX_ENABLE_WERROR "Fail and stop if a warning is triggered." OFF)
-option(LIBCXX_ENABLE_CXX1Y "Enable -std=c++1y and use of c++1y language features if the compiler supports it." OFF)
 option(LIBCXX_ENABLE_SHARED "Build libc++ as a shared library." ON)
-option(LIBCXX_ENABLE_GLOBAL_FILESYSTEM_NAMESPACE "Build libc++ with support for the global filesystem namespace." ON)
-option(LIBCXX_ENABLE_STDIN "Build libc++ with support for stdin/std::cin." ON)
-option(LIBCXX_ENABLE_STDOUT "Build libc++ with support for stdout/std::cout." ON)
-option(LIBCXX_ENABLE_THREADS "Build libc++ with support for threads." ON)
-option(LIBCXX_ENABLE_THREAD_UNSAFE_C_FUNCTIONS "Build libc++ with support for thread-unsafe C functions" ON)
-option(LIBCXX_BUILD_32_BITS "Build 32 bit libc++" OFF)
-option(LIBCXX_ENABLE_MONOTONIC_CLOCK
-  "Build libc++ with support for a monotonic clock.
-   This option may only be used when LIBCXX_ENABLE_THREADS=OFF." ON)
+
+option(LIBCXX_INCLUDE_TESTS "Build the libc++ tests." ${LLVM_INCLUDE_TESTS})
+option(LIBCXX_INCLUDE_DOCS "Build the libc++ documentation." ${LLVM_INCLUDE_DOCS})
+set(LIBCXX_LIBDIR_SUFFIX "${LLVM_LIBDIR_SUFFIX}" CACHE STRING
+    "Define suffix of library directory name (32/64)")
 option(LIBCXX_INSTALL_HEADERS "Install the libc++ headers." ON)
+option(LIBCXX_INSTALL_LIBRARY "Install the libc++ library." ON)
 option(LIBCXX_INSTALL_SUPPORT_HEADERS "Install libc++ support headers." ON)
-option(LIBCXX_GENERATE_COVERAGE "Enable generating code coverage." OFF)
-set(LIBCXX_COVERAGE_LIBRARY "" CACHE STRING
-       "The Profile-rt library used to build with code coverage")
-option(LIBCXX_ENABLE_STATIC_ABI_LIBRARY "Statically link the ABI library" OFF)
-set(LIBCXX_SYSROOT "" CACHE STRING "Use alternate sysroot.")
-set(LIBCXX_GCC_TOOLCHAIN "" CACHE STRING "Use alternate GCC toolchain.")
-if (LIBCXX_BUILT_STANDALONE)
-  set(LLVM_USE_SANITIZER "" CACHE STRING
-      "Define the sanitizer used to build the library and tests")
-endif()
-
-if (LIBCXX_ENABLE_STATIC_ABI_LIBRARY)
-  if (APPLE)
-    message(FATAL_ERROR "LIBCXX_ENABLE_STATIC_ABI_LIBRARY is not supported on OS X")
-  else()
-    message(WARNING "LIBCXX_ENABLE_STATIC_ABI_LIBRARY is an experimental option")
-  endif()
-endif()
+set(LIBCXX_ABI_VERSION 1 CACHE STRING "ABI version of libc++.")
+option(LIBCXX_ABI_UNSTABLE "Unstable ABI of libc++." OFF)
 
+# ABI Library options ---------------------------------------------------------
+set(LIBCXX_CXX_ABI "${LIBCXX_CXX_ABI}" CACHE STRING
+    "Specify C++ ABI library to use." FORCE)
 set(CXXABIS none libcxxabi libcxxrt libstdc++ libsupc++)
+set_property(CACHE LIBCXX_CXX_ABI PROPERTY STRINGS ;${CXXABIS})
+
+# Setup the default options if LIBCXX_CXX_ABI is not specified.
 if (NOT LIBCXX_CXX_ABI)
   if (NOT DEFINED LIBCXX_BUILT_STANDALONE AND
       IS_DIRECTORY "${CMAKE_SOURCE_DIR}/projects/libcxxabi")
@@ -97,14 +79,139 @@ if (NOT LIBCXX_CXX_ABI)
 else ()
   set(LIBCXX_CXX_ABI_LIBNAME "${LIBCXX_CXX_ABI}")
 endif ()
-set(LIBCXX_CXX_ABI "${LIBCXX_CXX_ABI}" CACHE STRING
-    "Specify C++ ABI library to use." FORCE)
-set_property(CACHE LIBCXX_CXX_ABI PROPERTY STRINGS ;${CXXABIS})
+
+# Use a static copy of the ABI library when linking libc++. This option
+# cannot be used with LIBCXX_ENABLE_ABI_LINKER_SCRIPT.
+option(LIBCXX_ENABLE_STATIC_ABI_LIBRARY "Statically link the ABI library" OFF)
+
+# Generate and install a linker script inplace of libc++.so. The linker script
+# will link libc++ to the correct ABI library. This option is on by default
+# On UNIX platforms other than Apple unless 'LIBCXX_ENABLE_STATIC_ABI_LIBRARY'
+# is on. This option is also disabled when the ABI library is not specified
+# or is specified to be "none".
+set(ENABLE_LINKER_SCRIPT_DEFAULT_VALUE OFF)
+if (LLVM_HAVE_LINK_VERSION_SCRIPT AND NOT LIBCXX_ENABLE_STATIC_ABI_LIBRARY
+      AND NOT LIBCXX_CXX_ABI_LIBNAME STREQUAL "none"
+      AND PYTHONINTERP_FOUND)
+    set(ENABLE_LINKER_SCRIPT_DEFAULT_VALUE ON)
+endif()
+
+option(LIBCXX_ENABLE_ABI_LINKER_SCRIPT
+      "Use and install a linker script for the given ABI library"
+      ${ENABLE_LINKER_SCRIPT_DEFAULT_VALUE})
 
 # Build libc++abi with libunwind. We need this option to determine whether to
 # link with libunwind or libgcc_s while running the test cases.
 option(LIBCXXABI_USE_LLVM_UNWINDER "Build and use the LLVM unwinder." OFF)
 
+# Target options --------------------------------------------------------------
+option(LIBCXX_BUILD_32_BITS "Build 32 bit libc++." ${LLVM_BUILD_32_BITS})
+set(LIBCXX_SYSROOT "" CACHE STRING "Use alternate sysroot.")
+set(LIBCXX_GCC_TOOLCHAIN "" CACHE STRING "Use alternate GCC toolchain.")
+
+# Feature options -------------------------------------------------------------
+option(LIBCXX_ENABLE_EXCEPTIONS "Use exceptions." ON)
+option(LIBCXX_ENABLE_RTTI "Use run time type information." ON)
+option(LIBCXX_ENABLE_GLOBAL_FILESYSTEM_NAMESPACE "Build libc++ with support for the global filesystem namespace." ON)
+option(LIBCXX_ENABLE_STDIN "Build libc++ with support for stdin/std::cin." ON)
+option(LIBCXX_ENABLE_STDOUT "Build libc++ with support for stdout/std::cout." ON)
+option(LIBCXX_ENABLE_THREADS "Build libc++ with support for threads." ON)
+option(LIBCXX_ENABLE_THREAD_UNSAFE_C_FUNCTIONS "Build libc++ with support for thread-unsafe C functions" ON)
+option(LIBCXX_ENABLE_MONOTONIC_CLOCK
+  "Build libc++ with support for a monotonic clock.
+   This option may only be set to OFF when LIBCXX_ENABLE_THREADS=OFF." ON)
+option(LIBCXX_HAS_MUSL_LIBC "Build libc++ with support for the Musl C library" OFF)
+
+# Misc options ----------------------------------------------------------------
+# FIXME: Turn -pedantic back ON. It is currently off because it warns
+# about #include_next which is used everywhere.
+option(LIBCXX_ENABLE_PEDANTIC "Compile with pedantic enabled." OFF)
+option(LIBCXX_ENABLE_WERROR "Fail and stop if a warning is triggered." OFF)
+
+option(LIBCXX_GENERATE_COVERAGE "Enable generating code coverage." OFF)
+set(LIBCXX_COVERAGE_LIBRARY "" CACHE STRING
+    "The Profile-rt library used to build with code coverage")
+
+# Don't allow a user to accidentally overwrite the system libc++ installation on Darwin.
+# If the user specifies -DCMAKE_INSTALL_PREFIX=/usr the install rules for libc++
+# will not be generated and a warning will be issued.
+option(LIBCXX_OVERRIDE_DARWIN_INSTALL "Enable overwriting darwins libc++ installation." OFF)
+mark_as_advanced(LIBCXX_OVERRIDE_DARWIN_INSTALL) # Don't show this option by default.
+
+if (${CMAKE_SYSTEM_NAME} MATCHES "Darwin" AND NOT LIBCXX_OVERRIDE_DARWIN_INSTALL)
+  if ("${CMAKE_INSTALL_PREFIX}" STREQUAL "/usr")
+    message(WARNING "Disabling libc++ install rules because installation would "
+                    "overwrite the systems installation. Configure with "
+                    "-DLIBCXX_OVERRIDE_DARWIN_INSTALL=ON to suppress this behaviour.")
+    mark_as_advanced(CLEAR LIBCXX_OVERRIDE_DARWIN_INSTALL) # Show the override option.
+    set(LIBCXX_INSTALL_HEADERS OFF)
+    set(LIBCXX_INSTALL_LIBRARY OFF)
+  endif()
+endif()
+
+set(LIBCXX_CONFIGURE_IDE_DEFAULT OFF)
+if (XCODE OR MSVC_IDE)
+  set(LIBCXX_CONFIGURE_IDE_DEFAULT ON)
+endif()
+option(LIBCXX_CONFIGURE_IDE "Configure libcxx for use within an IDE"
+      ${LIBCXX_CONFIGURE_IDE_DEFAULT})
+
+#===============================================================================
+# Check option configurations
+#===============================================================================
+
+# Ensure LIBCXX_ENABLE_MONOTONIC_CLOCK is set to ON only when
+# LIBCXX_ENABLE_THREADS is on.
+if(LIBCXX_ENABLE_THREADS AND NOT LIBCXX_ENABLE_MONOTONIC_CLOCK)
+  message(FATAL_ERROR "LIBCXX_ENABLE_MONOTONIC_CLOCK can only be set to OFF"
+                      " when LIBCXX_ENABLE_THREADS is also set to OFF.")
+endif()
+
+# Ensure LLVM_USE_SANITIZER is not specified when LIBCXX_GENERATE_COVERAGE
+# is ON.
+if (LLVM_USE_SANITIZER AND LIBCXX_GENERATE_COVERAGE)
+  message(FATAL_ERROR "LLVM_USE_SANITIZER cannot be used with LIBCXX_GENERATE_COVERAGE")
+endif()
+
+# Set LIBCXX_BUILD_32_BITS to (LIBCXX_BUILD_32_BITS OR LLVM_BUILD_32_BITS)
+# and check that we can build with 32 bits if requested.
+if (CMAKE_SIZEOF_VOID_P EQUAL 8 AND NOT WIN32)
+  if (LIBCXX_BUILD_32_BITS AND NOT LLVM_BUILD_32_BITS) # Don't duplicate the output from LLVM
+    message(STATUS "Building 32 bits executables and libraries.")
+  endif()
+elseif(LIBCXX_BUILD_32_BITS)
+  message(FATAL_ERROR "LIBCXX_BUILD_32_BITS=ON is not supported on this platform.")
+endif()
+
+# Check that this option is not enabled on Apple and emit a usage warning.
+if (LIBCXX_ENABLE_STATIC_ABI_LIBRARY)
+  if (APPLE)
+    message(FATAL_ERROR "LIBCXX_ENABLE_STATIC_ABI_LIBRARY is not supported on OS X")
+  else()
+    message(WARNING "LIBCXX_ENABLE_STATIC_ABI_LIBRARY is an experimental option")
+  endif()
+endif()
+
+if (LIBCXX_ENABLE_ABI_LINKER_SCRIPT)
+    if (APPLE)
+      message(FATAL_ERROR "LIBCXX_ENABLE_ABI_LINKER_SCRIPT cannot be used on APPLE targets")
+    endif()
+    if (NOT PYTHONINTERP_FOUND)
+      message(FATAL_ERROR "LIBCXX_ENABLE_ABI_LINKER_SCRIPT requires python but it was not found.")
+    endif()
+endif()
+
+if (LIBCXX_ENABLE_STATIC_ABI_LIBRARY AND LIBCXX_ENABLE_ABI_LINKER_SCRIPT)
+    message(FATAL_ERROR "Conflicting options given.
+        LIBCXX_ENABLE_STATIC_ABI_LIBRARY cannot be specified with
+        LIBCXX_ENABLE_ABI_LINKER_SCRIPT")
+endif()
+
+if (LIBCXX_HAS_MUSL_LIBC AND NOT LIBCXX_INSTALL_SUPPORT_HEADERS)
+  message(FATAL_ERROR "LIBCXX_INSTALL_SUPPORT_HEADERS can not be turned off"
+                      "when building for Musl with LIBCXX_HAS_MUSL_LIBC.")
+endif()
+
 #===============================================================================
 # Configure System
 #===============================================================================
@@ -114,232 +221,183 @@ set(LIBCXX_SOURCE_DIR  ${CMAKE_CURRENT_SOURCE_DIR})
 set(LIBCXX_BINARY_DIR  ${CMAKE_CURRENT_BINARY_DIR})
 set(LIBCXX_LIBRARY_DIR ${CMAKE_BINARY_DIR}/lib${LIBCXX_LIBDIR_SUFFIX})
 
+set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${LIBCXX_LIBRARY_DIR})
+set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${LIBCXX_LIBRARY_DIR})
+
 # Declare libc++ configuration variables.
 # They are intended for use as follows:
 # LIBCXX_CXX_FLAGS: General flags for both the compiler and linker.
 # LIBCXX_COMPILE_FLAGS: Compile only flags.
 # LIBCXX_LINK_FLAGS: Linker only flags.
-set(LIBCXX_CXX_FLAGS "")
 set(LIBCXX_COMPILE_FLAGS "")
 set(LIBCXX_LINK_FLAGS "")
+set(LIBCXX_LIBRARIES "")
 
 # Configure compiler.
 include(config-ix)
-# Configure ABI library
-include(HandleLibCXXABI)
+
 # Configure coverage options.
 if (LIBCXX_GENERATE_COVERAGE)
   include(CodeCoverage)
   set(CMAKE_BUILD_TYPE "COVERAGE" CACHE STRING "" FORCE)
 endif()
 
+string(TOUPPER "${CMAKE_BUILD_TYPE}" uppercase_CMAKE_BUILD_TYPE)
+
 #===============================================================================
 # Setup Compiler Flags
 #===============================================================================
 
-# Get required flags.
-# On all systems the system c++ standard library headers need to be excluded.
-if (MSVC)
-  # MSVC only has -X, which disables all default includes; including the crt.
-  # Thus, we do nothing and hope we don't accidentally include any of the C++
-  # headers.
-else()
-  if (LIBCXX_HAS_NOSTDINCXX_FLAG)
-    list(APPEND LIBCXX_COMPILE_FLAGS -nostdinc++)
-    string(REPLACE "-stdlib=libc++" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
-    string(REPLACE "-stdlib=libstdc++" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
-  endif()
-  # If c++1y has been enabled then attempt to use it. Fail if it is no supported
-  # by the compiler. Otherwise choose c++11 and ensure the compiler supports it.
-  if (LIBCXX_ENABLE_CXX1Y)
-    if (LIBCXX_HAS_STDCXX1Y_FLAG)
-      set(LIBCXX_STD_VERSION c++1y)
-    else()
-      message(FATAL_ERROR "c++1y was enabled but the compiler does not support it.")
-    endif()
-  else()
-    if (LIBCXX_HAS_STDCXX11_FLAG)
-      set(LIBCXX_STD_VERSION c++11)
-    else()
-      message(FATAL_ERROR "c++11 is required by libc++ but is not supported by the compiler")
-    endif()
-  endif()
-  # LIBCXX_STD_VERSION should always be set at this point.
-  list(APPEND LIBCXX_CXX_FLAGS "-std=${LIBCXX_STD_VERSION}")
-endif()
+include(HandleLibCXXABI) # Steup the ABI library flags
 
-macro(append_if list condition var)
-  if (${condition})
-    list(APPEND ${list} ${var})
-  endif()
-endmacro()
+# Include macros for adding and removing libc++ flags.
+include(HandleLibcxxFlags)
 
-# Get warning flags
-if (NOT MSVC)
-  append_if(LIBCXX_COMPILE_FLAGS LIBCXX_HAS_WALL_FLAG -Wall)
-  list(APPEND LIBCXX_COMPILE_FLAGS -Werror=return-type)
+# Remove flags that may have snuck in.
+remove_flags(-DNDEBUG -UNDEBUG -D_DEBUG
+             -stdlib=libc++ -stdlib=libstdc++ -lc++abi -m32)
+
+# FIXME(EricWF): See the FIXME on LIBCXX_ENABLE_PEDANTIC.
+# Remove the -pedantic flag and -Wno-pedantic and -pedantic-errors
+# so they don't get transformed into -Wno and -errors respectivly.
+remove_flags(-Wno-pedantic -pedantic-errors -pedantic)
+
+# Required flags ==============================================================
+add_compile_flags_if_supported(-std=c++11)
+if (NOT MSVC AND NOT LIBCXX_SUPPORTS_STD_EQ_CXX11_FLAG)
+  message(FATAL_ERROR "C++11 is required but the compiler does not support -std=c++11")
 endif()
 
-append_if(LIBCXX_COMPILE_FLAGS LIBCXX_HAS_W_FLAG -W)
-append_if(LIBCXX_COMPILE_FLAGS LIBCXX_HAS_WNO_UNUSED_PARAMETER_FLAG -Wno-unused-parameter)
-append_if(LIBCXX_COMPILE_FLAGS LIBCXX_HAS_WWRITE_STRINGS_FLAG -Wwrite-strings)
-append_if(LIBCXX_COMPILE_FLAGS LIBCXX_HAS_WNO_LONG_LONG_FLAG -Wno-long-long)
+# On all systems the system c++ standard library headers need to be excluded.
+# MSVC only has -X, which disables all default includes; including the crt.
+# Thus, we do nothing and hope we don't accidentally include any of the C++
+# headers
+add_compile_flags_if_supported(-nostdinc++)
+
+# Target flags ================================================================
+add_flags_if(LIBCXX_BUILD_32_BITS -m32)
+add_flags_if(LIBCXX_TARGET_TRIPLE "-target ${LIBCXX_TARGET_TRIPLE}")
+add_flags_if(LIBCXX_SYSROOT "--sysroot ${LIBCXX_SYSROOT}")
+add_flags_if(LIBCXX_GCC_TOOLCHAIN "-gcc-toolchain ${LIBCXX_GCC_TOOLCHAIN}")
+
+# Warning flags ===============================================================
+add_definitions(-D_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+add_compile_flags_if_supported(
+    -Wall -W -Wwrite-strings
+    -Wno-unused-parameter -Wno-long-long
+    -Werror=return-type)
 if (LIBCXX_ENABLE_WERROR)
-  append_if(LIBCXX_COMPILE_FLAGS LIBCXX_HAS_WERROR_FLAG -Werror)
-  append_if(LIBCXX_COMPILE_FLAGS LIBCXX_HAS_WX_FLAG -WX)
+  add_compile_flags_if_supported(-Werror)
+  add_compile_flags_if_supported(-WX)
 else()
-  append_if(LIBCXX_COMPILE_FLAGS LIBCXX_HAS_WNO_ERROR_FLAG -Wno-error)
-  append_if(LIBCXX_COMPILE_FLAGS LIBCXX_HAS_NO_WX_FLAG -WX-)
+  # TODO(EricWF) Remove this. We shouldn't be suppressing errors when -Werror is
+  # added elsewhere.
+  add_compile_flags_if_supported(-Wno-error)
 endif()
 if (LIBCXX_ENABLE_PEDANTIC)
-  append_if(LIBCXX_COMPILE_FLAGS LIBCXX_HAS_PEDANTIC_FLAG -pedantic)
+  add_compile_flags_if_supported(-pedantic)
 endif()
 
-# Get feature flags.
-# Exceptions
+# Exception flags =============================================================
 if (LIBCXX_ENABLE_EXCEPTIONS)
   # Catches C++ exceptions only and tells the compiler to assume that extern C
   # functions never throw a C++ exception.
-  append_if(LIBCXX_CXX_FLAGS LIBCXX_HAS_EHSC_FLAG -EHsc)
+  add_compile_flags_if_supported(-EHsc)
 else()
-  list(APPEND LIBCXX_CXX_FLAGS -D_LIBCPP_NO_EXCEPTIONS)
-  append_if(LIBCXX_CXX_FLAGS LIBCXX_HAS_NO_EHS_FLAG -EHs-)
-  append_if(LIBCXX_CXX_FLAGS LIBCXX_HAS_NO_EHA_FLAG -EHa-)
-  append_if(LIBCXX_CXX_FLAGS LIBCXX_HAS_FNO_EXCEPTIONS_FLAG -fno-exceptions)
+  add_definitions(-D_LIBCPP_NO_EXCEPTIONS)
+  add_compile_flags_if_supported(-EHs- -EHa-)
+  add_compile_flags_if_supported(-fno-exceptions)
 endif()
-# RTTI
+
+# RTTI flags ==================================================================
 if (NOT LIBCXX_ENABLE_RTTI)
-  list(APPEND LIBCXX_CXX_FLAGS -D_LIBCPP_NO_RTTI)
-  append_if(LIBCXX_CXX_FLAGS LIBCXX_HAS_NO_GR_FLAG -GR-)
-  append_if(LIBCXX_CXX_FLAGS LIBCXX_HAS_FNO_RTTI_FLAG -fno-rtti)
+  add_definitions(-D_LIBCPP_NO_RTTI)
+  add_compile_flags_if_supported(-GR-)
+  add_compile_flags_if_supported(-fno-rtti)
 endif()
-# Assert
-string(TOUPPER "${CMAKE_BUILD_TYPE}" uppercase_CMAKE_BUILD_TYPE)
+
+# Assertion flags =============================================================
+define_if(LIBCXX_ENABLE_ASSERTIONS -UNDEBUG)
+define_if_not(LIBCXX_ENABLE_ASSERTIONS -DNDEBUG)
 if (LIBCXX_ENABLE_ASSERTIONS)
   # MSVC doesn't like _DEBUG on release builds. See PR 4379.
-  if (NOT MSVC)
-    list(APPEND LIBCXX_COMPILE_FLAGS -D_DEBUG)
-  endif()
-  # On Release builds cmake automatically defines NDEBUG, so we
-  # explicitly undefine it:
-  if (uppercase_CMAKE_BUILD_TYPE STREQUAL "RELEASE")
-    list(APPEND LIBCXX_COMPILE_FLAGS -UNDEBUG)
-  endif()
-else()
-  if (NOT uppercase_CMAKE_BUILD_TYPE STREQUAL "RELEASE")
-    list(APPEND LIBCXX_COMPILE_FLAGS -DNDEBUG)
-  endif()
-endif()
-# Static library
-if (NOT LIBCXX_ENABLE_SHARED)
-  list(APPEND LIBCXX_COMPILE_FLAGS -D_LIBCPP_BUILD_STATIC)
+  define_if_not(MSVC -D_DEBUG)
 endif()
 
-if (CMAKE_SIZEOF_VOID_P EQUAL 8 AND NOT WIN32)
-  if (LIBCXX_BUILD_32_BITS)
-    message(STATUS "Building 32 bits executables and libraries.")
-    list(APPEND LIBCXX_CXX_FLAGS "-m32")
-  endif()
-elseif(LIBCXX_BUILD_32_BITS)
-  message(FATAL_ERROR "LIBCXX_BUILD_32_BITS=ON is not supported on this platform.")
-endif()
-# This is the _ONLY_ place where add_definitions is called.
-if (MSVC)
-  add_definitions(-D_CRT_SECURE_NO_WARNINGS)
-endif()
-
-# LIBCXX_ENABLE_GLOBAL_FILESYSTEM_NAMESPACE configuration
-if (NOT LIBCXX_ENABLE_GLOBAL_FILESYSTEM_NAMESPACE)
-  add_definitions(-D_LIBCPP_HAS_NO_GLOBAL_FILESYSTEM_NAMESPACE)
-endif()
-
-# LIBCXX_ENABLE_STDIN configuration
-if (NOT LIBCXX_ENABLE_STDIN)
-  add_definitions(-D_LIBCPP_HAS_NO_STDIN)
-endif()
+# Feature flags ===============================================================
+define_if(MSVC -D_CRT_SECURE_NO_WARNINGS)
 
-# LIBCXX_ENABLE_STDOUT configuration
-if (NOT LIBCXX_ENABLE_STDOUT)
-  add_definitions(-D_LIBCPP_HAS_NO_STDOUT)
-endif()
-
-# LIBCXX_ENABLE_THREADS configuration
-if (NOT LIBCXX_ENABLE_THREADS)
-  add_definitions(-D_LIBCPP_HAS_NO_THREADS)
-  if (NOT LIBCXX_ENABLE_MONOTONIC_CLOCK)
-    add_definitions(-D_LIBCPP_HAS_NO_MONOTONIC_CLOCK)
-  endif()
-# Ensure LIBCXX_ENABLE_MONOTONIC_CLOCK is set to ON.
-elseif(NOT LIBCXX_ENABLE_MONOTONIC_CLOCK)
-  message(FATAL_ERROR "LIBCXX_ENABLE_MONOTONIC_CLOCK can only be set to OFF"
-                      " when LIBCXX_ENABLE_THREADS is also set to OFF.")
-endif()
-
-# LIBCXX_ENABLE_THREAD_UNSAFE_C_FUNCTIONS configuration
-if (NOT LIBCXX_ENABLE_THREAD_UNSAFE_C_FUNCTIONS)
-  add_definitions(-D_LIBCPP_HAS_NO_THREAD_UNSAFE_C_FUNCTIONS)
-endif()
+# Sanitizer flags =============================================================
 
 # Configure for sanitizers. If LIBCXX_BUILT_STANDALONE then we have to do
 # the flag translation ourselves. Othewise LLVM's CMakeList.txt will handle it.
 if (LIBCXX_BUILT_STANDALONE)
+  set(LLVM_USE_SANITIZER "" CACHE STRING
+      "Define the sanitizer used to build the library and tests")
   # NOTE: LLVM_USE_SANITIZER checks for a UNIX like system instead of MSVC.
   # But we don't have LLVM_ON_UNIX so checking for MSVC is the best we can do.
   if (LLVM_USE_SANITIZER AND NOT MSVC)
-    append_if(LIBCXX_CXX_FLAGS LIBCXX_HAS_FNO_OMIT_FRAME_POINTER_FLAG
-              "-fno-omit-frame-pointer")
+    add_flags_if_supported("-fno-omit-frame-pointer")
+    add_flags_if_supported("-gline-tables-only")
+
     if (NOT uppercase_CMAKE_BUILD_TYPE STREQUAL "DEBUG" AND
         NOT uppercase_CMAKE_BUILD_TYPE STREQUAL "RELWITHDEBINFO")
-      append_if(LIBCXX_CXX_FLAGS LIBCXX_HAS_GLINE_TABLES_ONLY_FLAG
-                "-gline-tables-only")
+        add_flags_if_supported("-gline-tables-only")
     endif()
     if (LLVM_USE_SANITIZER STREQUAL "Address")
-      list(APPEND LIBCXX_CXX_FLAGS "-fsanitize=address")
+      add_flags("-fsanitize=address")
     elseif (LLVM_USE_SANITIZER MATCHES "Memory(WithOrigins)?")
-      list(APPEND LIBCXX_CXX_FLAGS "-fsanitize=memory")
+      add_flags(-fsanitize=memory)
       if (LLVM_USE_SANITIZER STREQUAL "MemoryWithOrigins")
-        list(APPEND LIBCXX_CXX_FLAGS "-fsanitize-memory-track-origins")
+        add_flags("-fsanitize-memory-track-origins")
       endif()
     elseif (LLVM_USE_SANITIZER STREQUAL "Undefined")
-      list(APPEND LIBCXX_CXX_FLAGS
-          "-fsanitize=undefined -fno-sanitize=vptr,function -fno-sanitize-recover")
+      add_flags("-fsanitize=undefined -fno-sanitize=vptr,function -fno-sanitize-recover=all")
     elseif (LLVM_USE_SANITIZER STREQUAL "Thread")
-      list(APPEND LIBCXX_CXX_FLAGS "-fsanitize=thread")
+      add_flags(-fsanitize=thread)
     else()
       message(WARNING "Unsupported value of LLVM_USE_SANITIZER: ${LLVM_USE_SANITIZER}")
     endif()
-  elseif(MSVC)
-    message(WARNING "LLVM_USE_SANITIZER is not supported with MSVC")
+  elseif(LLVM_USE_SANITIZER AND MSVC)
+    message(WARNING "LLVM_USE_SANITIZER is not supported on this platform.")
   endif()
 endif()
 
-append_if(LIBCXX_CXX_FLAGS LIBCXX_TARGET_TRIPLE
-          "-target ${LIBCXX_TARGET_TRIPLE}")
-
-append_if(LIBCXX_CXX_FLAGS LIBCXX_SYSROOT "--sysroot ${LIBCXX_SYSROOT}")
-append_if(LIBCXX_CXX_FLAGS LIBCXX_GCC_TOOLCHAIN
-          "-gcc-toolchain ${LIBCXX_GCC_TOOLCHAIN}")
-
-if (LLVM_USE_SANITIZER AND LIBCXX_GENERATE_COVERAGE)
-  message(FATAL_ERROR "LLVM_USE_SANITIZER cannot be used with LIBCXX_GENERATE_COVERAGE")
+# Configuration file flags =====================================================
+if (NOT LIBCXX_ABI_VERSION EQUAL "1")
+  config_define(${LIBCXX_ABI_VERSION} _LIBCPP_ABI_VERSION)
+endif()
+config_define_if(LIBCXX_ABI_UNSTABLE _LIBCPP_ABI_UNSTABLE)
+
+config_define_if_not(LIBCXX_ENABLE_GLOBAL_FILESYSTEM_NAMESPACE _LIBCPP_HAS_NO_GLOBAL_FILESYSTEM_NAMESPACE)
+config_define_if_not(LIBCXX_ENABLE_STDIN _LIBCPP_HAS_NO_STDIN)
+config_define_if_not(LIBCXX_ENABLE_STDOUT _LIBCPP_HAS_NO_STDOUT)
+config_define_if_not(LIBCXX_ENABLE_THREADS _LIBCPP_HAS_NO_THREADS)
+config_define_if_not(LIBCXX_ENABLE_MONOTONIC_CLOCK _LIBCPP_HAS_NO_MONOTONIC_CLOCK)
+config_define_if_not(LIBCXX_ENABLE_THREAD_UNSAFE_C_FUNCTIONS _LIBCPP_HAS_NO_THREAD_UNSAFE_C_FUNCTIONS)
+
+config_define_if(LIBCXX_HAS_MUSL_LIBC _LIBCPP_HAS_MUSL_LIBC)
+
+if (LIBCXX_NEEDS_SITE_CONFIG)
+  configure_file(
+    include/__config_site.in
+    ${LIBCXX_BINARY_DIR}/__config_site
+    @ONLY)
+  # Provide the config definitions by included the generated __config_site
+  # file at compile time.
+  add_compile_flags("-include ${LIBCXX_BINARY_DIR}/__config_site")
 endif()
-
-string(REPLACE ";" " " LIBCXX_CXX_FLAGS "${LIBCXX_CXX_FLAGS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${LIBCXX_CXX_FLAGS}")
 
 #===============================================================================
-# Setup Source Code
+# Setup Source Code And Tests
 #===============================================================================
-
 include_directories(include)
 add_subdirectory(include)
-
-# Add source code. This also contains all of the logic for deciding linker flags
-# soname, etc...
 add_subdirectory(lib)
 
-#===============================================================================
-# Setup Tests
-#===============================================================================
-
-add_subdirectory(test)
+if (LIBCXX_INCLUDE_TESTS)
+  add_subdirectory(test)
+endif()
+if (LIBCXX_INCLUDE_DOCS)
+  add_subdirectory(docs)
+endif()