1 files changed, 22 insertions, 13 deletions
diff --git a/Tests/CTestConfig/CMakeLists.txt b/Tests/CTestConfig/CMakeLists.txt
index f46d89a..8c19adb 100644
--- a/Tests/CTestConfig/CMakeLists.txt
+++ b/Tests/CTestConfig/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 2.8)
+cmake_minimum_required(VERSION 3.9)
 project(CTestConfig)
 
 include(CTest)
@@ -8,32 +8,41 @@ include(CTest)
 # 'ctest -S script.cmake' call.
 #
 # In either case, we expect CMAKE_BUILD_TYPE to be defined for single-configuration
-# build trees and not defined for multi-configuration build trees.
+# build trees and not defined for multi-configuration build trees. The value of
+# CMAKE_CONFIGURATION_TYPES should not be relied upon to determine whether we
+# are using a multi-config generator or not, the GENERATOR_IS_MULTI_CONFIG
+# global property is the canonical way to do that as of CMake 3.9.
 #
-if(CMAKE_CONFIGURATION_TYPES)
-  # multi-configuration: expect not defined, error if defined
+get_property(_isMultiConfig GLOBAL PROPERTY GENERATOR_IS_MULTI_CONFIG)
+if(_isMultiConfig)
+  if(NOT DEFINED CMAKE_CONFIGURATION_TYPES OR CMAKE_CONFIGURATION_TYPES STREQUAL "")
+    message(FATAL_ERROR "CMAKE_CONFIGURATION_TYPES is not defined or is empty "
+        "(but must be defined and non-empty for a multi-configuration generator)")
+  endif()
   if(DEFINED CMAKE_BUILD_TYPE AND NOT CMAKE_BUILD_TYPE STREQUAL "")
-    message(FATAL_ERROR "CMAKE_CONFIGURATION_TYPES='${CMAKE_CONFIGURATION_TYPES}' CMAKE_BUILD_TYPE='${CMAKE_BUILD_TYPE}' is defined and non-empty (but should not be for a multi-configuration generator)")
+    message(FATAL_ERROR "CMAKE_BUILD_TYPE='${CMAKE_BUILD_TYPE}' is defined and non-empty "
+        "(but should not be for a multi-configuration generator)")
   endif()
+  set(_configs ${CMAKE_CONFIGURATION_TYPES})
 else()
-  # single-configuration: expect defined, error if not defined
+  # Populating CMAKE_CONFIGURATION_TYPES even for single config generators is
+  # common enough for user projects that we don't want to consider it an error.
+  # We just need CMAKE_BUILD_TYPE to be set and ignore CMAKE_CONFIGURATION_TYPES.
   if(NOT DEFINED CMAKE_BUILD_TYPE OR CMAKE_BUILD_TYPE STREQUAL "")
-    message(FATAL_ERROR "CMAKE_BUILD_TYPE is not defined or is empty (but should be defined and non-empty for a single-configuration generator)")
+    message(FATAL_ERROR "CMAKE_BUILD_TYPE is not defined or is empty "
+        "(but should be defined and non-empty for a single-configuration generator)")
   endif()
-endif()
-
-
-if(DEFINED CMAKE_BUILD_TYPE AND NOT CMAKE_BUILD_TYPE STREQUAL "")
   add_definitions(-DCMAKE_BUILD_TYPE="${CMAKE_BUILD_TYPE}")
+  set(_configs ${CMAKE_BUILD_TYPE})
 endif()
 
 add_executable(ctc CTestConfig.cxx)
 
 
-foreach(cfg ${CMAKE_CONFIGURATION_TYPES} ${CMAKE_BUILD_TYPE})
+foreach(cfg ${_configs})
   add_test(NAME ctc-${cfg} CONFIGURATIONS ${cfg} COMMAND ctc --config $<CONFIGURATION>)
 
-  if(CMAKE_CONFIGURATION_TYPES)
+  if(_isMultiConfig)
     set_property(TEST ctc-${cfg}
       PROPERTY PASS_REGULAR_EXPRESSION "CMAKE_INTDIR is ${cfg}")
     set_property(TEST ctc-${cfg}