From 72728e12806ae4f85c7ab79b92f2d1c20981d596 Mon Sep 17 00:00:00 2001
From: Petr Hosek <phosek@google.com>
Date: Wed, 10 Mar 2021 11:21:41 -0800
Subject: [PATCH] [libcxxabi] Use cxx-headers target to consume libcxx headers

Rather than including libc++ include dir, use the cxx-headers target.

Differential Revision: https://reviews.llvm.org/D98367
---
 libcxxabi/CMakeLists.txt                | 18 ++++++++++++++++--
 libcxxabi/src/CMakeLists.txt            |  6 ++----
 libcxxabi/test/libcxxabi/test/config.py |  5 ++---
 3 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/libcxxabi/CMakeLists.txt b/libcxxabi/CMakeLists.txt
index 8b0c88689df3..dcbfdcb44700 100644
--- a/libcxxabi/CMakeLists.txt
+++ b/libcxxabi/CMakeLists.txt
@@ -156,9 +156,23 @@ if (NOT LIBCXXABI_ENABLE_SHARED AND NOT LIBCXXABI_ENABLE_STATIC)
   message(FATAL_ERROR "libc++abi must be built as either a shared or static library.")
 endif()
 
-set(LIBCXXABI_LIBCXX_INCLUDES "${LIBCXXABI_LIBCXX_PATH}/include" CACHE PATH
+# TODO: This is a workaround for the fact that Standalone builds can't use
+# targets from the other runtimes (so the cxx-headers target doesn't exist).
+set(LIBCXXABI_LIBCXX_INCLUDES "" CACHE PATH
     "Specify path to libc++ includes.")
-message(STATUS "Libc++abi will be using libc++ includes from ${LIBCXXABI_LIBCXX_INCLUDES}")
+if (LIBCXXABI_STANDALONE_BUILD)
+  if (NOT IS_DIRECTORY ${LIBCXXABI_LIBCXX_INCLUDES})
+    message(FATAL_ERROR
+      "LIBCXXABI_LIBCXX_INCLUDES=${LIBCXXABI_LIBCXX_INCLUDES} is not a valid directory. "
+      "Please provide the path to where the libc++ headers have been installed.")
+  endif()
+  add_library(cxx-headers INTERFACE)
+  if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC" OR "${CMAKE_CXX_SIMULATE_ID}" STREQUAL "MSVC")
+    target_compile_options(cxx-headers INTERFACE /I "${LIBCXXABI_LIBCXX_INCLUDES}")
+  else()
+    target_compile_options(cxx-headers INTERFACE -I "${LIBCXXABI_LIBCXX_INCLUDES}")
+  endif()
+endif()
 
 option(LIBCXXABI_HERMETIC_STATIC_LIBRARY
   "Do not export any symbols from the static library." OFF)
diff --git a/libcxxabi/src/CMakeLists.txt b/libcxxabi/src/CMakeLists.txt
index ea8c54589006..a2945f00bc25 100644
--- a/libcxxabi/src/CMakeLists.txt
+++ b/libcxxabi/src/CMakeLists.txt
@@ -55,8 +55,6 @@ if (MSVC_IDE OR XCODE)
   endif()
 endif()
 
-include_directories("${LIBCXXABI_LIBCXX_INCLUDES}")
-
 # stdlib_stdexcept.cpp depends on libc++ internals.
 include_directories("${LIBCXXABI_LIBCXX_PATH}")
 
@@ -177,7 +175,7 @@ endif()
 # Build the shared library.
 if (LIBCXXABI_ENABLE_SHARED)
   add_library(cxxabi_shared SHARED ${LIBCXXABI_SOURCES} ${LIBCXXABI_HEADERS})
-  target_link_libraries(cxxabi_shared PRIVATE ${LIBCXXABI_SHARED_LIBRARIES} ${LIBCXXABI_LIBRARIES})
+  target_link_libraries(cxxabi_shared PRIVATE cxx-headers ${LIBCXXABI_SHARED_LIBRARIES} ${LIBCXXABI_LIBRARIES})
   if (TARGET pstl::ParallelSTL)
     target_link_libraries(cxxabi_shared PUBLIC pstl::ParallelSTL)
   endif()
@@ -244,7 +242,7 @@ endif()
 # Build the static library.
 if (LIBCXXABI_ENABLE_STATIC)
   add_library(cxxabi_static STATIC ${LIBCXXABI_SOURCES} ${LIBCXXABI_HEADERS})
-  target_link_libraries(cxxabi_static PRIVATE ${LIBCXXABI_STATIC_LIBRARIES} ${LIBCXXABI_LIBRARIES})
+  target_link_libraries(cxxabi_static PRIVATE cxx-headers ${LIBCXXABI_STATIC_LIBRARIES} ${LIBCXXABI_LIBRARIES})
   if (TARGET pstl::ParallelSTL)
     target_link_libraries(cxxabi_static PUBLIC pstl::ParallelSTL)
   endif()
diff --git a/libcxxabi/test/libcxxabi/test/config.py b/libcxxabi/test/libcxxabi/test/config.py
index 280a60a864bc..80337711e07b 100644
--- a/libcxxabi/test/libcxxabi/test/config.py
+++ b/libcxxabi/test/libcxxabi/test/config.py
@@ -57,9 +57,8 @@ class Configuration(LibcxxConfiguration):
 
     def configure_compile_flags_header_includes(self):
         self.configure_config_site_header()
-        cxx_headers = self.get_lit_conf(
-            'cxx_headers',
-            os.path.join(self.libcxx_src_root, '/include'))
+        cxx_headers = self.get_lit_conf('cxx_headers', None) or \
+            os.path.join(self.project_obj_root, 'include', 'c++', 'v1')
         if cxx_headers == '':
             self.lit_config.note('using the systems c++ headers')
         else: