[cmake] Export driver template to fix standalone build

[nikic]

Summary

Export the driver-template.cpp.in file so that tools using GENERATE_DRIVER work in standalone builds (currently only relevant for clang). I've given the file an llvm- prefix, as we're now searching for the file in CMAKE_MODULE_PATH.

[abrachet]

llvm/cmake/modules/AddLLVM.cmake

899

Should we just break() out of the loop here?

llvm/cmake/modules/AddLLVM.cmake

if(ARG_DEPENDS)
       add_dependencies(${obj_name} ${ARG_DEPENDS})
     endif()
 
     set_target_properties(${obj_name} PROPERTIES FOLDER "Object Libraries")
   endif()
 
   if (ARG_GENERATE_DRIVER)
     string(REPLACE "-" "_" TOOL_NAME ${name})
+    foreach(path ${CMAKE_MODULE_PATH})
+      if(EXISTS ${path}/llvm-driver-template.cpp.in)
         configure_file(
-      ${LLVM_MAIN_SRC_DIR}/cmake/driver-template.cpp.in
+          ${path}/llvm-driver-template.cpp.in
           ${CMAKE_CURRENT_BINARY_DIR}/${name}-driver.cpp)
+        break()
+      endif()
+    endforeach()
 
     list(APPEND ALL_FILES ${CMAKE_CURRENT_BINARY_DIR}/${name}-driver.cpp)
 
     set_property(GLOBAL APPEND PROPERTY LLVM_DRIVER_COMPONENTS ${LLVM_LINK_COMPONENTS})
     set_property(GLOBAL APPEND PROPERTY LLVM_DRIVER_DEPS ${ARG_DEPENDS} ${LLVM_COMMON_DEPENDS})
     set_property(GLOBAL APPEND PROPERTY LLVM_DRIVER_OBJLIBS "${obj_name}")
     
     set_property(GLOBAL APPEND PROPERTY LLVM_DRIVER_TOOLS ${name})

llvm/cmake/modules/CMakeLists.txt

if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
   install(DIRECTORY .
     DESTINATION ${LLVM_INSTALL_PACKAGE_DIR}
     COMPONENT cmake-exports
     FILES_MATCHING PATTERN *.cmake
     PATTERN LLVMConfig.cmake EXCLUDE
     PATTERN LLVMConfigExtensions.cmake EXCLUDE
     PATTERN LLVMConfigVersion.cmake EXCLUDE
     PATTERN LLVM-Config.cmake EXCLUDE
-    PATTERN GetHostTriple.cmake EXCLUDE)
+    PATTERN GetHostTriple.cmake EXCLUDE
+    PATTERN llvm-driver-template.cpp.in)
 
   if (NOT LLVM_ENABLE_IDE)
     # Add a dummy target so this can be used with LLVM_DISTRIBUTION_COMPONENTS
     add_custom_target(cmake-exports)
     add_llvm_install_targets(install-cmake-exports
                              COMPONENT cmake-exports)
   endif()
 endif()