Drop old CMake "build settings" export/import

The CMakeExportBuildSettings and CMakeImportBuildSettings modules used
to export compiler paths and flags from one project and import them into
another.  The import process would force the settings on the including
project.

Forcing settings helped long ago when compiler ABIs changed frequently
but is now just a nuisance.  We've deemed the behavior harmful so this
commit simply removes it.  The modules and macros now error out if
included or called from a project that requires CMake 2.8 or higher.

4 files changed, 32 insertions, 282 deletions

diff --git a/Modules/CMakeBuildSettings.cmake.in b/Modules/CMakeBuildSettings.cmake.in
index b018ada..7c4aa14 100644
--- a/Modules/CMakeBuildSettings.cmake.in
+++ b/Modules/CMakeBuildSettings.cmake.in
@@ -1,29 +1,13 @@
-# This file has been automatically generated by CMake.  DO NOT EDIT!
-# It contains the build configuration for @PROJECT_NAME@.  The command
-# CMAKE_EXPORT_BUILD_SETTINGS(...) was used by @PROJECT_NAME@ to
-# generate this file.  Another project can use
-# CMAKE_IMPORT_BUILD_SETTINGS(...) to load the build configuration
-# from this file.  The contents of this file may be different across
-# versions of CMake.  The values set here should not be used by user
-# code.
 
-SET(CMAKE_BUILD_SETTING_CMAKE_MAJOR_VERSION "@CMAKE_MAJOR_VERSION@")
-SET(CMAKE_BUILD_SETTING_CMAKE_MINOR_VERSION "@CMAKE_MINOR_VERSION@")
-SET(CMAKE_BUILD_SETTING_PROJECT_NAME "@PROJECT_NAME@")
-
-SET(CMAKE_BUILD_SETTING_C_COMPILER "@CMAKE_C_COMPILER@")
-SET(CMAKE_BUILD_SETTING_C_FLAGS "@CMAKE_C_FLAGS@")
-SET(CMAKE_BUILD_SETTING_C_FLAGS_DEBUG "@CMAKE_C_FLAGS_DEBUG@")
-SET(CMAKE_BUILD_SETTING_C_FLAGS_RELEASE "@CMAKE_C_FLAGS_RELEASE@")
-SET(CMAKE_BUILD_SETTING_C_FLAGS_MINSIZEREL "@CMAKE_C_FLAGS_MINSIZEREL@")
-SET(CMAKE_BUILD_SETTING_C_FLAGS_RELWITHDEBINFO "@CMAKE_C_FLAGS_RELWITHDEBINFO@")
-
-SET(CMAKE_BUILD_SETTING_CXX_COMPILER "@CMAKE_CXX_COMPILER@")
-SET(CMAKE_BUILD_SETTING_CXX_FLAGS "@CMAKE_CXX_FLAGS@")
-SET(CMAKE_BUILD_SETTING_CXX_FLAGS_DEBUG "@CMAKE_CXX_FLAGS_DEBUG@")
-SET(CMAKE_BUILD_SETTING_CXX_FLAGS_RELEASE "@CMAKE_CXX_FLAGS_RELEASE@")
-SET(CMAKE_BUILD_SETTING_CXX_FLAGS_MINSIZEREL "@CMAKE_CXX_FLAGS_MINSIZEREL@")
-SET(CMAKE_BUILD_SETTING_CXX_FLAGS_RELWITHDEBINFO "@CMAKE_CXX_FLAGS_RELWITHDEBINFO@")
-
-SET(CMAKE_BUILD_SETTING_BUILD_TYPE "@CMAKE_BUILD_TYPE@")
-SET(CMAKE_BUILD_SETTING_BUILD_TOOL "@CMAKE_BUILD_TOOL@")
+# The command CMAKE_EXPORT_BUILD_SETTINGS(...) was used by
+# @PROJECT_NAME@ to generate this file.  As of CMake 2.8 the
+# functionality of this command has been dropped as it was deemed
+# harmful (confusing users by changing their compiler).
+
+# CMake 2.6 and below do not support loading their equivalent of this
+# file if it was produced by a newer version of CMake.  CMake 2.8 and
+# above simply do not load this file.  Therefore we simply error out.
+message(FATAL_ERROR
+  "This @PROJECT_NAME@ was built by CMake @CMAKE_VERSION@, but this is CMake "
+  "${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION}.${CMAKE_PATCH_VERSION}.  "
+  "Please upgrade CMake to a more recent version.")
diff --git a/Modules/CMakeExportBuildSettings.cmake b/Modules/CMakeExportBuildSettings.cmake
index 0c71efa..b14455b 100644
--- a/Modules/CMakeExportBuildSettings.cmake
+++ b/Modules/CMakeExportBuildSettings.cmake
@@ -1,7 +1,18 @@
-# - export build settings from a project.
-#  CMAKE_EXPORT_BUILD_SETTINGS(SETTINGS_FILE)
-# macro defined to export the build settings for use by another project.
-#  SETTINGS_FILE - the file into which the settings are to be stored.
+
+# This module is purposely no longer documented.  It does nothing useful.
+IF(NOT "${CMAKE_MINIMUM_REQUIRED_VERSION}" VERSION_LESS 2.7)
+  MESSAGE(FATAL_ERROR
+    "The functionality of this module has been dropped as of CMake 2.8.  "
+    "It was deemed harmful (confusing users by changing their compiler).  "
+    "Please remove calls to the CMAKE_EXPORT_BUILD_SETTINGS macro and "
+    "stop including this module.  "
+    "If this project generates any files for use by external projects, "
+    "remove any use of the CMakeImportBuildSettings module from them.")
+ENDIF()
+
+# This macro used to store build settings of a project in a file to be
+# loaded by another project using CMAKE_IMPORT_BUILD_SETTINGS.  Now it
+# creates a file that refuses to load (with comment explaining why).
 MACRO(CMAKE_EXPORT_BUILD_SETTINGS SETTINGS_FILE)
   IF(${SETTINGS_FILE} MATCHES ".+")
     CONFIGURE_FILE(${CMAKE_ROOT}/Modules/CMakeBuildSettings.cmake.in
diff --git a/Modules/CMakeImportBuildSettings.cmake b/Modules/CMakeImportBuildSettings.cmake
index 529b2ed..647084f 100644
--- a/Modules/CMakeImportBuildSettings.cmake
+++ b/Modules/CMakeImportBuildSettings.cmake
@@ -1,249 +1,10 @@
-# - import build settings from another project
-#  CMAKE_IMPORT_BUILD_SETTINGS(SETTINGS_FILE) 
-# macro defined to import the build settings from another project.  
-# SETTINGS_FILE is a file created by the other project's call to the
-# CMAKE_EXPORT_BUILD_SETTINGS macro, see CMakeExportBuildSettings.
-MACRO(CMAKE_IMPORT_BUILD_SETTINGS SETTINGS_FILE)
-  IF(${SETTINGS_FILE} MATCHES ".+")
-    # Load the settings.
-    INCLUDE(${SETTINGS_FILE})
-
-    # Check the CMake version that stored the settings.
-    IF(${CMAKE_BUILD_SETTING_CMAKE_MAJOR_VERSION}.${CMAKE_BUILD_SETTING_CMAKE_MINOR_VERSION}
-       GREATER ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
-      MESSAGE(SEND_ERROR
-              "${CMAKE_BUILD_SETTING_PROJECT_NAME} was built using CMake "
-              "${CMAKE_BUILD_SETTING_CMAKE_MAJOR_VERSION}.${CMAKE_BUILD_SETTING_CMAKE_MINOR_VERSION}, "
-              "but this is CMake${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION}.  "
-              "Please upgrade CMake to a more recent version.")
-    ENDIF(${CMAKE_BUILD_SETTING_CMAKE_MAJOR_VERSION}.${CMAKE_BUILD_SETTING_CMAKE_MINOR_VERSION}
-       GREATER ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
-
-    # Check the build tool.
-    SET(CMAKE_BUILD_TOOL1 "")
-    IF(CMAKE_BUILD_TOOL)
-      GET_FILENAME_COMPONENT (CMAKE_BUILD_TOOL1 ${CMAKE_BUILD_TOOL} NAME_WE)
-      STRING(TOLOWER ${CMAKE_BUILD_TOOL1} CMAKE_BUILD_TOOL1)
-    ENDIF(CMAKE_BUILD_TOOL)
-    SET(CMAKE_BUILD_TOOL2 "")
-    IF(CMAKE_BUILD_SETTING_BUILD_TOOL)
-      GET_FILENAME_COMPONENT (CMAKE_BUILD_TOOL2 ${CMAKE_BUILD_SETTING_BUILD_TOOL} NAME_WE)
-      STRING(TOLOWER ${CMAKE_BUILD_TOOL2} CMAKE_BUILD_TOOL2)
-    ENDIF(CMAKE_BUILD_SETTING_BUILD_TOOL)
-    STRING(COMPARE NOTEQUAL "x${CMAKE_BUILD_TOOL1}" "x${CMAKE_BUILD_TOOL2}"
-           CMAKE_BUILD_TOOL_MISMATCH)
-
-    IF(CMAKE_BUILD_SETTING_BUILD_TOOL MATCHES "^msdev$")
-      SET(CMAKE_IMPORT_BUILD_SETTINGS_IMPORTING_FROM_MS_STUDIO 1)
-    ENDIF(CMAKE_BUILD_SETTING_BUILD_TOOL MATCHES "^msdev$")
-    IF(CMAKE_BUILD_SETTING_BUILD_TOOL MATCHES "^devenv$")
-      SET(CMAKE_IMPORT_BUILD_SETTINGS_IMPORTING_FROM_MS_STUDIO 1)
-    ENDIF(CMAKE_BUILD_SETTING_BUILD_TOOL MATCHES "^devenv$")
-
-    # Check the C++ compiler setting.  If it is empty, the imported
-    # project is not a C++ project, and doesn't need a matching compiler.
-    IF(CMAKE_BUILD_SETTING_CXX_COMPILER)
-      IF(WIN32)
-        STRING(TOLOWER "x${CMAKE_CXX_COMPILER}" COMPARE_CXX_LOCAL)
-        STRING(TOLOWER "x${CMAKE_BUILD_SETTING_CXX_COMPILER}" COMPARE_CXX_REMOTE)
-        STRING(COMPARE NOTEQUAL "${COMPARE_CXX_LOCAL}" "${COMPARE_CXX_REMOTE}"
-          CMAKE_CXX_COMPILER_MISMATCH)
-      ELSE(WIN32)
-        STRING(COMPARE NOTEQUAL
-          "x${CMAKE_CXX_COMPILER}" "x${CMAKE_BUILD_SETTING_CXX_COMPILER}"
-          CMAKE_CXX_COMPILER_MISMATCH)
-      ENDIF(WIN32)
-    ENDIF(CMAKE_BUILD_SETTING_CXX_COMPILER)
-
-    # Check the C build variation flags.
-    STRING(COMPARE NOTEQUAL
-           "x${CMAKE_C_FLAGS_DEBUG}" "x${CMAKE_BUILD_SETTING_C_FLAGS_DEBUG}"
-           CMAKE_C_FLAGS_DEBUG_MISMATCH)
-    STRING(COMPARE NOTEQUAL
-           "x${CMAKE_C_FLAGS_RELEASE}" "x${CMAKE_BUILD_SETTING_C_FLAGS_RELEASE}"
-           CMAKE_C_FLAGS_RELEASE_MISMATCH)
-    STRING(COMPARE NOTEQUAL
-           "x${CMAKE_C_FLAGS_MINSIZEREL}" "x${CMAKE_BUILD_SETTING_C_FLAGS_MINSIZEREL}"
-           CMAKE_C_FLAGS_MINSIZEREL_MISMATCH)
-    STRING(COMPARE NOTEQUAL
-           "x${CMAKE_C_FLAGS_RELWITHDEBINFO}" "x${CMAKE_BUILD_SETTING_C_FLAGS_RELWITHDEBINFO}"
-           CMAKE_C_FLAGS_RELWITHDEBINFO_MISMATCH)
-
-    # Check the C++ build variation flags.
-    STRING(COMPARE NOTEQUAL
-           "x${CMAKE_CXX_FLAGS_DEBUG}" "x${CMAKE_BUILD_SETTING_CXX_FLAGS_DEBUG}"
-           CMAKE_CXX_FLAGS_DEBUG_MISMATCH)
-    STRING(COMPARE NOTEQUAL
-           "x${CMAKE_CXX_FLAGS_RELEASE}" "x${CMAKE_BUILD_SETTING_CXX_FLAGS_RELEASE}"
-           CMAKE_CXX_FLAGS_RELEASE_MISMATCH)
-    STRING(COMPARE NOTEQUAL
-           "x${CMAKE_CXX_FLAGS_MINSIZEREL}" "x${CMAKE_BUILD_SETTING_CXX_FLAGS_MINSIZEREL}"
-           CMAKE_CXX_FLAGS_MINSIZEREL_MISMATCH)
-    STRING(COMPARE NOTEQUAL
-           "x${CMAKE_CXX_FLAGS_RELWITHDEBINFO}" "x${CMAKE_BUILD_SETTING_CXX_FLAGS_RELWITHDEBINFO}"
-           CMAKE_CXX_FLAGS_RELWITHDEBINFO_MISMATCH)
-
-    # Check the build type.
-    SET(CMAKE_BUILD_TYPE_MISMATCH 0)
-    IF(WIN32)
-      IF(NOT CMAKE_IMPORT_BUILD_SETTINGS_IMPORTING_FROM_MS_STUDIO)
-        STRING(COMPARE NOTEQUAL
-               "x${CMAKE_BUILD_TYPE}" "x${CMAKE_BUILD_SETTING_BUILD_TYPE}"
-               CMAKE_BUILD_TYPE_MISMATCH)
-      ENDIF(NOT CMAKE_IMPORT_BUILD_SETTINGS_IMPORTING_FROM_MS_STUDIO)
-    ENDIF(WIN32)
-
-    # Build tool must match on Windows.
-    IF(WIN32)
-      IF(CMAKE_BUILD_TOOL_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
-        MESSAGE(SEND_ERROR
-                "This project, ${PROJECT_NAME}, depends on the project "
-                "${CMAKE_BUILD_SETTING_PROJECT_NAME}. Unfortunately "
-                "${CMAKE_BUILD_SETTING_PROJECT_NAME} was built using "
-                "\"${CMAKE_BUILD_TOOL2}\", but you are trying to build "
-                "${PROJECT_NAME} using \"${CMAKE_BUILD_TOOL1}\"."
-                "In order for this build to succeed, both projects must be "
-                "built with the same Generator. To change the Generator you "
-                "are using for the project ${PROJECT_NAME}, you must "
-                "delete the cache, and then rerun cmake and this "
-                "time select the same Generator that was used to build "
-                "${CMAKE_BUILD_SETTING_PROJECT_NAME}. If "
-                "${CMAKE_BUILD_SETTING_PROJECT_NAME} was built using a "
-                "generator that you do not have (for example it was built "
-                "with Visual Studio 6 and you only have 7) then you will "
-                "need to select a different version of "
-                "${CMAKE_BUILD_SETTING_PROJECT_NAME} or rebuild "
-                "${CMAKE_BUILD_SETTING_PROJECT_NAME} with the correct "
-                "generator. ")
-      ENDIF(CMAKE_BUILD_TOOL_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
-    ENDIF(WIN32)
-
-    # Enforce the C++ compiler setting.
-    # CMAKE_OVERRIDE_COMPILER_MISMATCH allow advanced user to override cmake detection of
-    # compiler mismatch between imported projects. Typical case on UNIX could be:
-    # 1. Compile a project with g++-3.3 while the imported project was configured
-    # using the 'c++' alias (which at the time meant g++-3.3)
-    # 2. This variable also becomes handy when the project your are importing has been
-    # compiled with a compiler you do not have access to, but offer a compatible ABI with
-    # yours.
-    # WARNING: Do not use this variable with C++ compiler with incompatible ABI
-    IF(CMAKE_CXX_COMPILER_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
-      MESSAGE("Warning: CMake is forcing CMAKE_CXX_COMPILER to "
-              "\"${CMAKE_BUILD_SETTING_CXX_COMPILER}\" to match that imported "
-              "from ${CMAKE_BUILD_SETTING_PROJECT_NAME}.  This is required "
-              "because C++ projects must use the same compiler.  "
-              "If this message appears for more than one imported project, "
-              "you have conflicting C++ compilers and will have to "
-              "re-build one of those projects. Was set to ${CMAKE_CXX_COMPILER}")
-      SET(CMAKE_CXX_COMPILER ${CMAKE_BUILD_SETTING_CXX_COMPILER}
-          CACHE STRING "C++ compiler imported from ${CMAKE_BUILD_SETTING_PROJECT_NAME}." FORCE)
-    ENDIF(CMAKE_CXX_COMPILER_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
-
-    # Enforce the build type.
-    IF(CMAKE_BUILD_TYPE_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
-      MESSAGE("Warning: CMake is forcing CMAKE_BUILD_TYPE to "
-              "\"${CMAKE_BUILD_SETTING_BUILD_TYPE}\" to match that imported "
-              "from ${CMAKE_BUILD_SETTING_PROJECT_NAME}.  This is required "
-              "because projects must use the same compiler settings.  "
-              "If this message appears for more than one imported project, "
-              "you have conflicting compiler settings and will have to "
-              "re-build one of those projects.")
-      SET(CMAKE_BUILD_TYPE ${CMAKE_BUILD_SETTING_BUILD_TYPE}
-          CACHE STRING "Build type imported from ${CMAKE_BUILD_SETTING_PROJECT_NAME}." FORCE)
-    ENDIF(CMAKE_BUILD_TYPE_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
 
-    # Enforce the C build variation flags.
-
-    IF(CMAKE_C_FLAGS_DEBUG_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
-      MESSAGE("Warning: CMake is forcing CMAKE_C_FLAGS_DEBUG to "
-              "\"${CMAKE_BUILD_SETTING_C_FLAGS_DEBUG}\" to match that imported "
-              "from ${CMAKE_BUILD_SETTING_PROJECT_NAME}.  "
-              "If this message appears for more than one imported project, "
-              "you have conflicting options and will have to "
-              "re-build one of those projects.")
-      SET(CMAKE_C_FLAGS_DEBUG ${CMAKE_BUILD_SETTING_C_FLAGS_DEBUG}
-          CACHE STRING "C DEBUG flags imported from ${CMAKE_BUILD_SETTING_PROJECT_NAME}." FORCE)
-    ENDIF(CMAKE_C_FLAGS_DEBUG_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
-
-    IF(CMAKE_C_FLAGS_RELEASE_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
-      MESSAGE("Warning: CMake is forcing CMAKE_C_FLAGS_RELEASE to "
-              "\"${CMAKE_BUILD_SETTING_C_FLAGS_RELEASE}\" to match that imported "
-              "from ${CMAKE_BUILD_SETTING_PROJECT_NAME}.  "
-              "If this message appears for more than one imported project, "
-              "you have conflicting options and will have to "
-              "re-build one of those projects.")
-      SET(CMAKE_C_FLAGS_RELEASE ${CMAKE_BUILD_SETTING_C_FLAGS_RELEASE}
-          CACHE STRING "C RELEASE flags imported from ${CMAKE_BUILD_SETTING_PROJECT_NAME}." FORCE)
-    ENDIF(CMAKE_C_FLAGS_RELEASE_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
-
-    IF(CMAKE_C_FLAGS_MINSIZEREL_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
-      MESSAGE("Warning: CMake is forcing CMAKE_C_FLAGS_MINSIZEREL to "
-              "\"${CMAKE_BUILD_SETTING_C_FLAGS_MINSIZEREL}\" to match that imported "
-              "from ${CMAKE_BUILD_SETTING_PROJECT_NAME}.  "
-              "If this message appears for more than one imported project, "
-              "you have conflicting options and will have to "
-              "re-build one of those projects.")
-      SET(CMAKE_C_FLAGS_MINSIZEREL ${CMAKE_BUILD_SETTING_C_FLAGS_MINSIZEREL}
-          CACHE STRING "C MINSIZEREL flags imported from ${CMAKE_BUILD_SETTING_PROJECT_NAME}." FORCE)
-    ENDIF(CMAKE_C_FLAGS_MINSIZEREL_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
-
-    IF(CMAKE_C_FLAGS_RELWITHDEBINFO_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
-      MESSAGE("Warning: CMake is forcing CMAKE_C_FLAGS_RELWITHDEBINFO to "
-              "\"${CMAKE_BUILD_SETTING_C_FLAGS_RELWITHDEBINFO}\" to match that imported "
-              "from ${CMAKE_BUILD_SETTING_PROJECT_NAME}.  "
-              "If this message appears for more than one imported project, "
-              "you have conflicting options and will have to "
-              "re-build one of those projects.")
-      SET(CMAKE_C_FLAGS_RELWITHDEBINFO ${CMAKE_BUILD_SETTING_C_FLAGS_RELWITHDEBINFO}
-          CACHE STRING "C RELWITHDEBINFO flags imported from ${CMAKE_BUILD_SETTING_PROJECT_NAME}." FORCE)
-    ENDIF(CMAKE_C_FLAGS_RELWITHDEBINFO_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
-
-    # Enforce the C++ build variation flags.
-
-    IF(CMAKE_CXX_FLAGS_DEBUG_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
-      MESSAGE("Warning: CMake is forcing CMAKE_CXX_FLAGS_DEBUG to "
-              "\"${CMAKE_BUILD_SETTING_CXX_FLAGS_DEBUG}\" to match that imported "
-              "from ${CMAKE_BUILD_SETTING_PROJECT_NAME}.  "
-              "If this message appears for more than one imported project, "
-              "you have conflicting options and will have to "
-              "re-build one of those projects.")
-      SET(CMAKE_CXX_FLAGS_DEBUG ${CMAKE_BUILD_SETTING_CXX_FLAGS_DEBUG}
-          CACHE STRING "C++ DEBUG flags imported from ${CMAKE_BUILD_SETTING_PROJECT_NAME}." FORCE)
-    ENDIF(CMAKE_CXX_FLAGS_DEBUG_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
-
-    IF(CMAKE_CXX_FLAGS_RELEASE_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
-      MESSAGE("Warning: CMake is forcing CMAKE_CXX_FLAGS_RELEASE to "
-              "\"${CMAKE_BUILD_SETTING_CXX_FLAGS_RELEASE}\" to match that imported "
-              "from ${CMAKE_BUILD_SETTING_PROJECT_NAME}.  "
-              "If this message appears for more than one imported project, "
-              "you have conflicting options and will have to "
-              "re-build one of those projects.")
-      SET(CMAKE_CXX_FLAGS_RELEASE ${CMAKE_BUILD_SETTING_CXX_FLAGS_RELEASE}
-          CACHE STRING "C++ RELEASE flags imported from ${CMAKE_BUILD_SETTING_PROJECT_NAME}." FORCE)
-    ENDIF(CMAKE_CXX_FLAGS_RELEASE_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
-
-    IF(CMAKE_CXX_FLAGS_MINSIZEREL_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
-      MESSAGE("Warning: CMake is forcing CMAKE_CXX_FLAGS_MINSIZEREL to "
-              "\"${CMAKE_BUILD_SETTING_CXX_FLAGS_MINSIZEREL}\" to match that imported "
-              "from ${CMAKE_BUILD_SETTING_PROJECT_NAME}.  "
-              "If this message appears for more than one imported project, "
-              "you have conflicting options and will have to "
-              "re-build one of those projects.")
-      SET(CMAKE_CXX_FLAGS_MINSIZEREL ${CMAKE_BUILD_SETTING_CXX_FLAGS_MINSIZEREL}
-          CACHE STRING "C++ MINSIZEREL flags imported from ${CMAKE_BUILD_SETTING_PROJECT_NAME}." FORCE)
-    ENDIF(CMAKE_CXX_FLAGS_MINSIZEREL_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
-
-    IF(CMAKE_CXX_FLAGS_RELWITHDEBINFO_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
-      MESSAGE("Warning: CMake is forcing CMAKE_CXX_FLAGS_RELWITHDEBINFO to "
-              "\"${CMAKE_BUILD_SETTING_CXX_FLAGS_RELWITHDEBINFO}\" to match that imported "
-              "from ${CMAKE_BUILD_SETTING_PROJECT_NAME}.  "
-              "If this message appears for more than one imported project, "
-              "you have conflicting options and will have to "
-              "re-build one of those projects.")
-      SET(CMAKE_CXX_FLAGS_RELWITHDEBINFO ${CMAKE_BUILD_SETTING_CXX_FLAGS_RELWITHDEBINFO}
-          CACHE STRING "C++ RELWITHDEBINFO flags imported from ${CMAKE_BUILD_SETTING_PROJECT_NAME}." FORCE)
-    ENDIF(CMAKE_CXX_FLAGS_RELWITHDEBINFO_MISMATCH AND NOT CMAKE_OVERRIDE_COMPILER_MISMATCH)
+# This module is purposely no longer documented.  It does nothing useful.
 
+# This macro used to load build settings from another project that
+# stored settings using the CMAKE_EXPORT_BUILD_SETTINGS macro.
+MACRO(CMAKE_IMPORT_BUILD_SETTINGS SETTINGS_FILE)
+  IF(${SETTINGS_FILE} MATCHES ".+")
   ELSE(${SETTINGS_FILE} MATCHES ".+")
     MESSAGE(SEND_ERROR "CMAKE_IMPORT_BUILD_SETTINGS called with no argument.")
   ENDIF(${SETTINGS_FILE} MATCHES ".+")
diff --git a/Modules/UseVTK40.cmake b/Modules/UseVTK40.cmake
index 750d44b..086f6da 100644
--- a/Modules/UseVTK40.cmake
+++ b/Modules/UseVTK40.cmake
@@ -5,12 +5,6 @@
 # be included only when FindVTK.cmake sets the VTK_USE_FILE variable
 # to point here.
 
-# Load the compiler settings used for VTK.
-IF(VTK_BUILD_SETTINGS_FILE)
-  INCLUDE(CMakeImportBuildSettings)
-  CMAKE_IMPORT_BUILD_SETTINGS(${VTK_BUILD_SETTINGS_FILE})
-ENDIF(VTK_BUILD_SETTINGS_FILE)
-
 # Add compiler flags needed to use VTK.
 SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${VTK_REQUIRED_C_FLAGS}")
 SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${VTK_REQUIRED_CXX_FLAGS}")