[CMake] Add clang's targets to LLVM's export set when not building standalone

[beanz]

Summary

CMake freaks out in trivial cases like:

cmake -G Ninja -DLLVM_ENABLE_PIC=Off -DLLVM_INSTALL_TOOLCHAIN_ONLY=On ../llvm

This is a result of static ink dependencies not all being part of the same export group, and was caused by r249935.

[hintonda]

Sorry the previous change caused this configuration to break. However, I'm not sure about adding LLVMExports here. Shouldn't that be handled in llvm/CMakeLists.txt?

In fact, this looks like a cmake bug (or feature) that won't let you export a target that depends on a static lib without also exporting that static lib. Since you've set LLVM_INSTALL_TOOLCHAIN_ONLY, you don't want to export those statics libs anyway, since they won't be available.

I'll play around with it and see if I can come up with something that works for all configurations.

[beanz]

@hintonda, your comment actually trigged something in my brain and I just realized the problem. It is a much simpler fix. If you set LLVM_ENABLE_PIC=Off libclang isn't built as a dylib, it is a static lib. If LLVM_INSTALL_TOOLCHAIN_ONLY=On, we need to exclude all static libraries from the Clang exports file.

[hintonda]

Ah, great. That is simpler.

CMakeLists.txt

if(LLVM_LIT)
       endif()
     else()
       set(LLVM_INCLUDE_TESTS OFF)
     endif()
   endif()
 
   set( CLANG_BUILT_STANDALONE 1 )
   set(BACKEND_PACKAGE_STRING "LLVM ${LLVM_PACKAGE_VERSION}")
+  set(EXPORT_GROUP ClangTargets)
 else()
   set(BACKEND_PACKAGE_STRING "${PACKAGE_STRING}")
+  set(EXPORT_GROUP LLVMExports)
 endif()
 
 find_package(LibXml2 2.5.3 QUIET)
 if (LIBXML2_FOUND)
   set(CLANG_HAVE_LIBXML 1)
 endif()
 
 set(CLANG_RESOURCE_DIR "" CACHE STRING
macro(add_clang_library name)
   llvm_add_library(${name} ${ARG_ENABLE_SHARED} ${ARG_UNPARSED_ARGUMENTS} ${srcs})
 
   if(TARGET ${name})
     target_link_libraries(${name} ${cmake_2_8_12_INTERFACE} ${LLVM_COMMON_LIBS})
 
     if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY OR ${name} STREQUAL "libclang")
       install(TARGETS ${name}
         COMPONENT ${name}
-        EXPORT ClangTargets
+        EXPORT ${EXPORT_GROUP}
         LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX}
         ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX}
         RUNTIME DESTINATION bin)
 
       if (${ARG_SHARED} AND NOT CMAKE_CONFIGURATION_TYPES)
         add_custom_target(install-${name}
                           DEPENDS ${name}
                           COMMAND "${CMAKE_COMMAND}"
option(CLANG_INCLUDE_DOCS "Generate build targets for the Clang docs."
   ${LLVM_INCLUDE_DOCS})
 if( CLANG_INCLUDE_DOCS )
   add_subdirectory(docs)
 endif()
 
 set(CLANG_ORDER_FILE "" CACHE FILEPATH
   "Order file to use when compiling clang in order to improve startup time.")
 
-if (CLANG_BUILT_STANDALONE OR CMAKE_VERSION VERSION_EQUAL 3 OR
-    CMAKE_VERSION VERSION_GREATER 3)
+if (CLANG_BUILT_STANDALONE)
   # Generate a list of CMake library targets so that other CMake projects can
   # link against them. LLVM calls its version of this file LLVMExports.cmake, but
   # the usual CMake convention seems to be ${Project}Targets.cmake.
   set(CLANG_INSTALL_PACKAGE_DIR share/clang/cmake)
   set(clang_cmake_builddir "${CMAKE_BINARY_DIR}/${CLANG_INSTALL_PACKAGE_DIR}")
   get_property(CLANG_EXPORTS GLOBAL PROPERTY CLANG_EXPORTS)
   export(TARGETS ${CLANG_EXPORTS} FILE ${clang_cmake_builddir}/ClangTargets.cmake)