Xcode: Detect CURRENT_ARCH for use by generator

During compiler identification, extract the Xcode `CURRENT_ARCH` value
and save it for later use by the Xcode generator in an internal compiler
information variable.  This will be useful to know the locations of
object files when only one architecture is built.

Modules/CMakeCCompiler.cmake.in

@@ -13,6 +13,7 @@ set(CMAKE_C_PLATFORM_ID "@CMAKE_C_PLATFORM_ID@")
 set(CMAKE_C_SIMULATE_ID "@CMAKE_C_SIMULATE_ID@")
 set(CMAKE_C_SIMULATE_VERSION "@CMAKE_C_SIMULATE_VERSION@")
 @SET_MSVC_C_ARCHITECTURE_ID@
+@SET_CMAKE_XCODE_CURRENT_ARCH@
 set(CMAKE_AR "@CMAKE_AR@")
 set(CMAKE_GCC_AR "@CMAKE_GCC_AR@")
 set(CMAKE_RANLIB "@CMAKE_RANLIB@")

Modules/CMakeCXXCompiler.cmake.in

@@ -14,6 +14,7 @@ set(CMAKE_CXX_PLATFORM_ID "@CMAKE_CXX_PLATFORM_ID@")
 set(CMAKE_CXX_SIMULATE_ID "@CMAKE_CXX_SIMULATE_ID@")
 set(CMAKE_CXX_SIMULATE_VERSION "@CMAKE_CXX_SIMULATE_VERSION@")
 @SET_MSVC_CXX_ARCHITECTURE_ID@
+@SET_CMAKE_XCODE_CURRENT_ARCH@
 set(CMAKE_AR "@CMAKE_AR@")
 set(CMAKE_GCC_AR "@CMAKE_GCC_AR@")
 set(CMAKE_RANLIB "@CMAKE_RANLIB@")

Modules/CMakeDetermineCCompiler.cmake

@@ -175,6 +175,11 @@ if(MSVC_C_ARCHITECTURE_ID)
     "set(MSVC_C_ARCHITECTURE_ID ${MSVC_C_ARCHITECTURE_ID})")
 endif()
 
+if(CMAKE_C_XCODE_CURRENT_ARCH)
+  set(SET_CMAKE_XCODE_CURRENT_ARCH
+    "set(CMAKE_XCODE_CURRENT_ARCH ${CMAKE_C_XCODE_CURRENT_ARCH})")
+endif()
+
 # configure variables set in this file for fast reload later on
 configure_file(${CMAKE_ROOT}/Modules/CMakeCCompiler.cmake.in
   ${CMAKE_PLATFORM_INFO_DIR}/CMakeCCompiler.cmake

Modules/CMakeDetermineCXXCompiler.cmake

@@ -170,6 +170,11 @@ if(MSVC_CXX_ARCHITECTURE_ID)
     "set(MSVC_CXX_ARCHITECTURE_ID ${MSVC_CXX_ARCHITECTURE_ID})")
 endif()
 
+if(CMAKE_CXX_XCODE_CURRENT_ARCH)
+  set(SET_CMAKE_XCODE_CURRENT_ARCH
+    "set(CMAKE_XCODE_CURRENT_ARCH ${CMAKE_CXX_XCODE_CURRENT_ARCH})")
+endif()
+
 # configure all variables set in this file
 configure_file(${CMAKE_ROOT}/Modules/CMakeCXXCompiler.cmake.in
   ${CMAKE_PLATFORM_INFO_DIR}/CMakeCXXCompiler.cmake

Modules/CMakeDetermineCompilerId.cmake

@@ -104,6 +104,7 @@ function(CMAKE_DETERMINE_COMPILER_ID lang flagvar src)
   set(CMAKE_${lang}_PLATFORM_ID "${CMAKE_${lang}_PLATFORM_ID}" PARENT_SCOPE)
   set(MSVC_${lang}_ARCHITECTURE_ID "${MSVC_${lang}_ARCHITECTURE_ID}"
     PARENT_SCOPE)
+  set(CMAKE_${lang}_XCODE_CURRENT_ARCH "${CMAKE_${lang}_XCODE_CURRENT_ARCH}" PARENT_SCOPE)
   set(CMAKE_${lang}_CL_SHOWINCLUDES_PREFIX "${CMAKE_${lang}_CL_SHOWINCLUDES_PREFIX}" PARENT_SCOPE)
   set(CMAKE_${lang}_COMPILER_VERSION "${CMAKE_${lang}_COMPILER_VERSION}" PARENT_SCOPE)
   set(CMAKE_${lang}_COMPILER_WRAPPER "${CMAKE_${lang}_COMPILER_WRAPPER}" PARENT_SCOPE)
@@ -358,6 +359,9 @@ Id flags: ${testflags} ${CMAKE_${lang}_COMPILER_ID_FLAGS_ALWAYS}
         endif()
       endif()
     endif()
+    if("${CMAKE_${lang}_COMPILER_ID_OUTPUT}" MATCHES "CURRENT_ARCH=([^%\r\n]+)[\r\n]")
+      set(CMAKE_${lang}_XCODE_CURRENT_ARCH "${CMAKE_MATCH_1}" PARENT_SCOPE)
+    endif()
   else()
     execute_process(
       COMMAND "${CMAKE_${lang}_COMPILER}"

Modules/CompilerId/Xcode-3.pbxproj.in

@@ -58,7 +58,7 @@
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 			shellPath = /bin/sh;
-			shellScript = "echo \"GCC_VERSION=$GCC_VERSION\"";
+			shellScript = "echo \"GCC_VERSION=$GCC_VERSION\" ; echo \"CURRENT_ARCH=$CURRENT_ARCH\"";
 			showEnvVarsInLog = 0;
 		};
 		2C18F0B515DC1DCE00593670 = {