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.

1 files changed, 12 insertions, 28 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.")