[libc++] Fix compiler-rt build by copying libc++ headers to <build>/i…

…nclude

This commit should really be named "Workaround external projects depending
on libc++ build system implementation details". It seems that the compiler-rt
build (and perhaps other projects) is relying on the fact that we copy libc++
and libc++abi headers to `<build-root>/include/c++/v1`. This was changed
by 5d79664, which moved the headers to `<build-root>/projects/libcxx/include/c++/v1`
and broke the compiler-rt build.

I'm committing this workaround to fix the compiler-rt build, but we should
remove reliance on implementation details like that. The correct way to
setup the compiler-rt build would be to "link" against the `cxx-headers`
target in CMake, or to run `install-cxx-headers` using an appropriate
installation prefix, and then manually add a `-I` path to that location.

libcxx/CMakeLists.txt

@@ -31,7 +31,6 @@ set(CMAKE_MODULE_PATH
 set(LIBCXX_SOURCE_DIR  ${CMAKE_CURRENT_SOURCE_DIR})
 set(LIBCXX_BINARY_DIR  ${CMAKE_CURRENT_BINARY_DIR})
 set(LIBCXX_BINARY_INCLUDE_DIR "${LIBCXX_BINARY_DIR}/include/c++build")
-set(LIBCXX_GENERATED_INCLUDE_DIR "${LIBCXX_BINARY_DIR}/include/c++/v1")
 
 if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR LIBCXX_STANDALONE_BUILD)
   project(libcxx CXX C)
@@ -398,21 +397,23 @@ endif ()
 # Configure System
 #===============================================================================
 
+# TODO: Other projects rely on the location where we generate the libc++ headers
+#       internally. We should get rid of these dependencies.
 if(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)
   set(LIBCXX_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR}/${LLVM_DEFAULT_TARGET_TRIPLE}/c++)
-  set(LIBCXX_HEADER_DIR ${LLVM_BINARY_DIR})
+  set(LIBCXX_GENERATED_INCLUDE_DIR "${LLVM_BINARY_DIR}/include/c++/v1")
   set(LIBCXX_INSTALL_LIBRARY_DIR lib${LLVM_LIBDIR_SUFFIX}/${LLVM_DEFAULT_TARGET_TRIPLE}/c++)
   if(LIBCXX_LIBDIR_SUBDIR)
     string(APPEND LIBCXX_LIBRARY_DIR /${LIBCXX_LIBDIR_SUBDIR})
     string(APPEND LIBCXX_INSTALL_LIBRARY_DIR /${LIBCXX_LIBDIR_SUBDIR})
   endif()
 elseif(LLVM_LIBRARY_OUTPUT_INTDIR)
   set(LIBCXX_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR})
-  set(LIBCXX_HEADER_DIR  ${LLVM_BINARY_DIR})
+  set(LIBCXX_GENERATED_INCLUDE_DIR  "${LLVM_BINARY_DIR}/include/c++/v1")
   set(LIBCXX_INSTALL_LIBRARY_DIR lib${LIBCXX_LIBDIR_SUFFIX})
 else()
   set(LIBCXX_LIBRARY_DIR ${CMAKE_BINARY_DIR}/lib${LIBCXX_LIBDIR_SUFFIX})
-  set(LIBCXX_HEADER_DIR  ${CMAKE_BINARY_DIR})
+  set(LIBCXX_GENERATED_INCLUDE_DIR  "${CMAKE_BINARY_DIR}/include/c++/v1")
   set(LIBCXX_INSTALL_LIBRARY_DIR lib${LIBCXX_LIBDIR_SUFFIX})
 endif()
 

libcxx/cmake/Modules/HandleLibCXXABI.cmake

@@ -52,8 +52,10 @@ macro(setup_abi_lib abidefines abishared abistatic abifiles abidirs)
             COMMENT "Copying C++ ABI header ${fpath}...")
         list(APPEND abilib_headers "${dst}")
 
-        if (LIBCXX_HEADER_DIR)
-          set(dst "${LIBCXX_HEADER_DIR}/include/c++/v1/${dstdir}/${fpath}")
+        if (LIBCXX_GENERATED_INCLUDE_DIR) # always true
+          # TODO: libc++ shouldn't be responsible for copying the libc++abi
+          #       headers into the right location.
+          set(dst "${LIBCXX_GENERATED_INCLUDE_DIR}/include/c++/v1/${dstdir}/${fpath}")
           add_custom_command(OUTPUT ${dst}
               DEPENDS ${src}
               COMMAND ${CMAKE_COMMAND} -E copy_if_different ${src} ${dst}

libcxx/include/CMakeLists.txt

@@ -185,7 +185,7 @@ if(LIBCXX_INSTALL_SUPPORT_HEADERS)
     )
 endif()
 
-if(LIBCXX_HEADER_DIR)
+if (LIBCXX_GENERATED_INCLUDE_DIR) # Always true
   configure_file("__config_site.in" "${LIBCXX_GENERATED_INCLUDE_DIR}/__config_site" @ONLY)
 
   set(_all_includes "${LIBCXX_GENERATED_INCLUDE_DIR}/__config_site")

libcxxabi/test/libcxxabi/test/config.py

@@ -58,7 +58,7 @@ def configure_compile_flags(self):
     def configure_compile_flags_header_includes(self):
         cxx_headers = self.get_lit_conf(
             'cxx_headers',
-            os.path.join(self.libcxx_obj_root, 'include', 'c++', 'v1'))
+            os.path.join(self.project_obj_root, 'include', 'c++', 'v1'))
         if cxx_headers == '':
             self.lit_config.note('using the systems c++ headers')
         else: