Bug 19462 - Use the INSTALL(EXPORT ...) to export CMake definitions

[beanz]

Summary

This patch moves all the clang library targets into a ClangTargets export list, and installs it using the CMake install(EXPORT...) command.

[beanz]

Stephen Kelly's comments in the bug (https://llvm.org/bugs/show_bug.cgi?id=19462) from 2015-02-25 indicate that these patches are fine as-is.

He also recommends we may want to consider namespacing our LLVM and Clang targets in our exported target files. According to the CMake documentation (http://www.cmake.org/cmake/help/v3.0/manual/cmake-packages.7.html):

"A NAMESPACE with double-colons is specified when exporting the targets for installation. This convention of double-colons gives CMake a hint that the name is an IMPORTED target when it is used by downstreams with the target_link_libraries() command. This way, CMake can issue a diagnostic if the package providing it has not yet been found."

This might be desirable, however it will require more testing.

Does anyone have any objection to these patches as they are now?

[rnk]

lgtm, let's do it, I think this just got lost for a bit.

CMakeLists.txt

macro(add_clang_library name)
   endif()
   llvm_add_library(${name} ${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 ${name}
+        EXPORT ClangTargets
         LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX}
         ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX}
         RUNTIME DESTINATION bin)
     endif()
     set_property(GLOBAL APPEND PROPERTY CLANG_EXPORTS ${name})
   else()
     # Add empty "phony" target
     add_custom_target(${name})
if (CLANG_BUILT_STANDALONE)
   # 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)
 
   # Install a <prefix>/share/clang/cmake/ClangConfig.cmake file so that
   # find_package(Clang) works. Install the target list with it.
+  install(EXPORT ClangTargets DESTINATION ${LLVM_INSTALL_PACKAGE_DIR})
+
   install(FILES
     ${CMAKE_CURRENT_SOURCE_DIR}/cmake/modules/ClangConfig.cmake
-    ${CLANG_BINARY_DIR}/share/clang/cmake/ClangTargets.cmake
     DESTINATION share/clang/cmake)
 
   # Also copy ClangConfig.cmake to the build directory so that dependent projects
   # can build against a build directory of Clang more easily.
   configure_file(
     ${CMAKE_CURRENT_SOURCE_DIR}/cmake/modules/ClangConfig.cmake
     ${CLANG_BINARY_DIR}/share/clang/cmake/ClangConfig.cmake
     COPYONLY)
 endif ()