[LLDB] Fix standalone LLDB build when LLVM/Clang were built with LLVM_INSTALL_TOOLCHAIN_ONLY=ON

[Eugene.Zelenko]

Summary

Patch also includes fix for CMake 2.8.12.2, see D18018.

[labath]

Looks reasonable to me. Let's give others a chance to respond though.

cmake/modules/LLDBStandalone.cmake

103 ↗

(On Diff #57539)

Please add a comment about when do we expect this files to exist. (I.e., when building against clang which was configured and built together with llvm).

113 ↗

(On Diff #57539)

Please add a comment about when do we expect these files to exist. (I.e., when building against an not-installed copy of llvm which is still sitting in its build directory).

[Eugene.Zelenko]

Add comments per Pavel suggestion.

[krytarowski]

I'm going to test it now.

[krytarowski]

It works for me.

lldb/trunk/cmake/modules/LLDBStandalone.cmake

 # If we are not building as a part of LLVM, build LLDB as an
 # standalone project, using LLVM as an external library:
 if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
   project(lldb)
   cmake_minimum_required(VERSION 2.8.12.2)
 
+  if (POLICY CMP0022)
+    cmake_policy(SET CMP0022 NEW) # automatic when 2.8.12 is required
+  endif()
+
   option(LLVM_INSTALL_TOOLCHAIN_ONLY "Only include toolchain files in the 'install' target." OFF)
 
   # Rely on llvm-config.
   set(CONFIG_OUTPUT)
   find_program(LLVM_CONFIG "llvm-config")
   if(LLVM_CONFIG)
     message(STATUS "Found LLVM_CONFIG as ${LLVM_CONFIG}")
     set(CONFIG_COMMAND ${LLVM_CONFIG}
if( NOT PYTHONINTERP_FOUND )
                Please install Python or specify the PYTHON_EXECUTABLE CMake variable.")
     endif()
   else()
     message("-- Found PythonInterp: ${PYTHON_EXECUTABLE}")
   endif()
 
   # Import CMake library targets from LLVM and Clang.
   include("${LLVM_OBJ_ROOT}/lib${LLVM_LIBDIR_SUFFIX}/cmake/llvm/LLVMConfig.cmake")
+  # cmake/clang/ClangConfig.cmake is not created when LLVM and Cland are built together.
+  if (EXISTS "${LLVM_OBJ_ROOT}/lib${LLVM_LIBDIR_SUFFIX}/cmake/clang/ClangConfig.cmake")
     include("${LLVM_OBJ_ROOT}/lib${LLVM_LIBDIR_SUFFIX}/cmake/clang/ClangConfig.cmake")
+  endif()
 
   set(PACKAGE_VERSION "${LLVM_PACKAGE_VERSION}")
 
   set(LLVM_BINARY_DIR ${CMAKE_BINARY_DIR})
 
   set(CMAKE_INCLUDE_CURRENT_DIR ON)
   include_directories("${LLVM_BINARY_DIR}/include" "${LLVM_MAIN_INCLUDE_DIR}")
+  # Next three include directories are needed when llvm-config is located in build directory.
+  # LLVM and Cland are assumed to be built together
+  if (EXISTS "${LLVM_OBJ_ROOT}/include")
+    include_directories("${LLVM_OBJ_ROOT}/include")
+  endif()
+  if (EXISTS "${LLVM_MAIN_SRC_DIR}/tools/clang/include")
+    include_directories("${LLVM_MAIN_SRC_DIR}/tools/clang/include")
+  endif()
+  if (EXISTS "${LLVM_OBJ_ROOT}/tools/clang/include")
+    include_directories("${LLVM_OBJ_ROOT}/tools/clang/include")
+  endif()
   link_directories("${LLVM_LIBRARY_DIR}")
 
   set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
   set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX})
   set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX})
 
   set(LLDB_BUILT_STANDALONE 1)
 endif()