From: Chris Bieneman <chris.bieneman@me.com>
Date: Mon, 8 Jul 2019 18:29:29 +0000 (+0000)
Subject: Fix issues building libraries as more than one type with Xcode
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=b513268c3813c989b34307dc626bae3994ab5110;p=llvm

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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@365365 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 041c847fd1a..1b5a6b9de98 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -40,6 +40,12 @@ if ((CMAKE_GENERATOR MATCHES "Visual Studio") AND (CMAKE_GENERATOR_TOOLSET STREQ
                   "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)
diff --git a/cmake/modules/AddLLVM.cmake b/cmake/modules/AddLLVM.cmake
index fc69cdfa430..d2ba017e3dd 100644
--- a/cmake/modules/AddLLVM.cmake
+++ b/cmake/modules/AddLLVM.cmake
@@ -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})