From 335a1278eba2d54c0ca7901e6bf6e40eb50743b6 Mon Sep 17 00:00:00 2001
From: Brad King <brad.king@kitware.com>
Date: Wed, 14 Aug 2013 19:16:42 -0400
Subject: [PATCH] OS X: Do not default to non-existent deployment target SDK

Since commit 95f78e08 (OS X: Search for SDK based on deployment target,
2013-08-02) we select the default OS X SDK path to match the deployment
target.  Fix this behavior in the case that the matching SDK does not
exist and fall back to the SDK for the current host OS X version.
---
 Modules/Platform/Darwin.cmake | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/Modules/Platform/Darwin.cmake b/Modules/Platform/Darwin.cmake
index db8c7ef8b..093088067 100644
--- a/Modules/Platform/Darwin.cmake
+++ b/Modules/Platform/Darwin.cmake
@@ -134,11 +134,23 @@ elseif("${CMAKE_GENERATOR}" MATCHES Xcode
     set(_CMAKE_OSX_SDKS_VER_SUFFIX_10.3 ".9")
     if(CMAKE_OSX_DEPLOYMENT_TARGET)
       set(_CMAKE_OSX_SDKS_VER ${CMAKE_OSX_DEPLOYMENT_TARGET}${_CMAKE_OSX_SDKS_VER_SUFFIX_${CMAKE_OSX_DEPLOYMENT_TARGET}})
+      set(_CMAKE_OSX_SYSROOT_CHECK "${_CMAKE_OSX_SDKS_DIR}/MacOSX${_CMAKE_OSX_SDKS_VER}.sdk")
+      if(IS_DIRECTORY "${_CMAKE_OSX_SYSROOT_CHECK}")
+        set(_CMAKE_OSX_SYSROOT_DEFAULT "${_CMAKE_OSX_SYSROOT_CHECK}")
+      else()
+        set(_CMAKE_OSX_SDKS_VER ${_CURRENT_OSX_VERSION}${_CMAKE_OSX_SDKS_VER_SUFFIX_${_CURRENT_OSX_VERSION}})
+        set(_CMAKE_OSX_SYSROOT_DEFAULT "${_CMAKE_OSX_SDKS_DIR}/MacOSX${_CMAKE_OSX_SDKS_VER}.sdk")
+        message(WARNING
+          "CMAKE_OSX_DEPLOYMENT_TARGET is '${CMAKE_OSX_DEPLOYMENT_TARGET}' "
+          "but the matching SDK does not exist at:\n \"${_CMAKE_OSX_SYSROOT_CHECK}\"\n"
+          "Instead using SDK:\n \"${_CMAKE_OSX_SYSROOT_DEFAULT}\"\n"
+          "matching the host OS X version."
+          )
+      endif()
     else()
       set(_CMAKE_OSX_SDKS_VER ${_CURRENT_OSX_VERSION}${_CMAKE_OSX_SDKS_VER_SUFFIX_${_CURRENT_OSX_VERSION}})
+      set(_CMAKE_OSX_SYSROOT_DEFAULT "${_CMAKE_OSX_SDKS_DIR}/MacOSX${_CMAKE_OSX_SDKS_VER}.sdk")
     endif()
-    set(_CMAKE_OSX_SYSROOT_DEFAULT
-      "${_CMAKE_OSX_SDKS_DIR}/MacOSX${_CMAKE_OSX_SDKS_VER}.sdk")
   else()
     # Assume developer files are in root (such as Xcode 4.5 command-line tools).
     set(_CMAKE_OSX_SYSROOT_DEFAULT "")