[compiler-rt] add_custom_libcxx should pass LLVM_PATH and a C++ compiler

[dsanders]

I noticed these issues while working on a better version of D16583 and thought I should post them separately.

[samsonov]

LGTM, but please address two comments below.

CMakeLists.txt

86

Consider adding COMPILER_RT_TEST_CXX_COMPILER here as well (initializing it from ${CMAKE_CXX_COMPILER}).

cmake/Modules/AddCompilerRT.cmake

301

This should be LLVM_MAIN_SRC_DIR

[dsanders]

Thanks. Both changes were made in the commit (r259493)

CMakeLists.txt

if (NOT COMPILER_RT_STANDALONE_BUILD)
   option(COMPILER_RT_INCLUDE_TESTS "Generate and build compiler-rt unit tests."
          ${LLVM_INCLUDE_TESTS})
  option(COMPILER_RT_ENABLE_WERROR "Fail and stop if warning is triggered"
         ${LLVM_ENABLE_WERROR})
   # Use just-built Clang to compile/link tests on all platforms, except for
   # Windows where we need to use clang-cl instead.
   if(NOT MSVC)
     set(COMPILER_RT_TEST_COMPILER ${LLVM_RUNTIME_OUTPUT_INTDIR}/clang)
+    set(COMPILER_RT_TEST_CXX_COMPILER ${LLVM_RUNTIME_OUTPUT_INTDIR}/clang++)
   else()
     set(COMPILER_RT_TEST_COMPILER ${LLVM_RUNTIME_OUTPUT_INTDIR}/clang.exe)
+    set(COMPILER_RT_TEST_CXX_COMPILER ${LLVM_RUNTIME_OUTPUT_INTDIR}/clang++.exe)
   endif()
 else()
   # Take output dir and install path from the user.
   set(COMPILER_RT_OUTPUT_DIR ${CMAKE_CURRENT_BINARY_DIR} CACHE PATH
     "Path where built compiler-rt libraries should be stored.")
   set(COMPILER_RT_EXEC_OUTPUT_DIR ${CMAKE_CURRENT_BINARY_DIR}/bin CACHE PATH
     "Path where built compiler-rt executables should be stored.")
   set(COMPILER_RT_INSTALL_PATH ${CMAKE_INSTALL_PREFIX} CACHE PATH
     "Path where built compiler-rt libraries should be installed.")
   option(COMPILER_RT_INCLUDE_TESTS "Generate and build compiler-rt unit tests." OFF)
   option(COMPILER_RT_ENABLE_WERROR "Fail and stop if warning is triggered" OFF)
   # Use a host compiler to compile/link tests.
   set(COMPILER_RT_TEST_COMPILER ${CMAKE_C_COMPILER} CACHE PATH "Compiler to use for testing")
 
   if (NOT LLVM_CONFIG_PATH)
     find_program(LLVM_CONFIG_PATH "llvm-config"
                  DOC "Path to llvm-config binary")
     if (NOT LLVM_CONFIG_PATH)
       message(FATAL_ERROR "llvm-config not found: specify LLVM_CONFIG_PATH")
     endif()
   endif()
   execute_process(

cmake/Modules/AddCompilerRT.cmake

if(NOT COMPILER_RT_STANDALONE_BUILD)
     list(APPEND LIBCXX_DEPS clang)
   endif()
 
   ExternalProject_Add(${name}
     PREFIX ${prefix}
     SOURCE_DIR ${COMPILER_RT_LIBCXX_PATH}
     CMAKE_ARGS -DCMAKE_MAKE_PROGRAM:STRING=${CMAKE_MAKE_PROGRAM}
                -DCMAKE_C_COMPILER=${COMPILER_RT_TEST_COMPILER}
-               -DCMAKE_CXX_COMPILER=${COMPILER_RT_TEST_COMPILER}
+               -DCMAKE_CXX_COMPILER=${COMPILER_RT_TEST_CXX_COMPILER}
                -DCMAKE_C_FLAGS=${LIBCXX_CFLAGS}
                -DCMAKE_CXX_FLAGS=${LIBCXX_CFLAGS}
                -DCMAKE_BUILD_TYPE=Release
                -DCMAKE_INSTALL_PREFIX:PATH=<INSTALL_DIR>
+               -DLLVM_PATH=${LLVM_SOURCE_DIR}
     LOG_BUILD 1
     LOG_CONFIGURE 1
     LOG_INSTALL 1
     )
   set_target_properties(${name} PROPERTIES EXCLUDE_FROM_ALL TRUE)
 
   ExternalProject_Add_Step(${name} force-reconfigure
     DEPENDERS configure