[llvm] r365365 - Fix issues building libraries as more than one type with Xcode

[Chris Bieneman via llvm-commits]

Author: cbieneman
Date: Mon Jul  8 11:29:29 2019
New Revision: 365365

URL: http://llvm.org/viewvc/llvm-project?rev=365365&view=rev
Log:
Fix issues building libraries as more than one type with Xcode

Summary:
CMake+Xcode doesn't seem to handle targets that only have object
sources. This patch works around that limitation by adding a dummy
soruce file to any library target that is generated by llvm_add_library
when object libraries are generated.

Object libraries are generated whenever llvm_add_library is passed more
than one library type, which is now the default case for clang static
libraries (which generate STATIC and OBJECT libraries).

Reviewers: zturner, compnerd, joanlluch

Reviewed By: joanlluch

Subscribers: joanlluch, xbolva00, mgorny, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64300

Modified:
    llvm/trunk/CMakeLists.txt
    llvm/trunk/cmake/modules/AddLLVM.cmake

Modified: llvm/trunk/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/CMakeLists.txt?rev=365365&r1=365364&r2=365365&view=diff
==============================================================================
--- llvm/trunk/CMakeLists.txt (original)
+++ llvm/trunk/CMakeLists.txt Mon Jul  8 11:29:29 2019
@@ -40,6 +40,12 @@ if ((CMAKE_GENERATOR MATCHES "Visual Stu
                   "host compiler, pass -Thost=x64 on the CMake command line.")
 endif()
 
+if (CMAKE_GENERATOR STREQUAL "Xcode" AND NOT CMAKE_OSX_ARCHITECTURES)
+  # Some CMake features like object libraries get confused if you don't
+  # explicitly specify an architecture setting with the Xcode generator.
+  set(CMAKE_OSX_ARCHITECTURES "x86_64")
+endif()
+
 project(LLVM
   VERSION ${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}.${LLVM_VERSION_PATCH}
   LANGUAGES C CXX ASM)

Modified: llvm/trunk/cmake/modules/AddLLVM.cmake
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/cmake/modules/AddLLVM.cmake?rev=365365&r1=365364&r2=365365&view=diff
==============================================================================
--- llvm/trunk/cmake/modules/AddLLVM.cmake (original)
+++ llvm/trunk/cmake/modules/AddLLVM.cmake Mon Jul  8 11:29:29 2019
@@ -433,7 +433,12 @@ function(llvm_add_library name)
       ${ALL_FILES}
       )
     llvm_update_compile_flags(${obj_name})
-    set(ALL_FILES "$<TARGET_OBJECTS:${obj_name}>")
+    if(CMAKE_GENERATOR STREQUAL "Xcode")
+      set(DUMMY_FILE ${CMAKE_CURRENT_BINARY_DIR}/Dummy.c)
+      file(WRITE ${DUMMY_FILE} "// This file intentionally empty\n")
+      set_property(SOURCE ${DUMMY_FILE} APPEND_STRING PROPERTY COMPILE_FLAGS "-Wno-empty-translation-unit")
+    endif()
+    set(ALL_FILES "$<TARGET_OBJECTS:${obj_name}>" ${DUMMY_FILE})
 
     # Do add_dependencies(obj) later due to CMake issue 14747.
     list(APPEND objlibs ${obj_name})