Tests: Execute compile features tests unconditionally.

Conditionally create a dummy test if there are no known features.

Tests/CMakeCommands/target_compile_features/CMakeLists.txt

@@ -1,6 +1,14 @@
 cmake_minimum_required(VERSION 3.0)
 project(target_compile_features)
 
+if (NOT CMAKE_CXX_COMPILE_FEATURES)
+  file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/test_dummy.cpp"
+    "int main(int,char**) { return 0; }\n"
+  )
+  add_executable(target_compile_features "${CMAKE_CURRENT_BINARY_DIR}/test_dummy.cpp")
+  return()
+endif()
+
 set(CMAKE_VERBOSE_MAKEFILE ON)
 
 add_executable(target_compile_features main.cpp)

Tests/CMakeLists.txt

@@ -197,11 +197,9 @@ if(BUILD_TESTING)
   ADD_TEST_MACRO(TarTest TarTest)
   ADD_TEST_MACRO(SystemInformation SystemInformation)
   ADD_TEST_MACRO(MathTest MathTest)
-  if(CMAKE_CXX_COMPILER_ID STREQUAL GNU
-      AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.8)
-    ADD_TEST_MACRO(CompileFeatures CompileFeatures)
-    ADD_TEST_MACRO(CMakeCommands.target_compile_features target_compile_features)
-  endif()
+  ADD_TEST_MACRO(CompileFeatures CompileFeatures)
+  ADD_TEST_MACRO(CMakeCommands.target_compile_features target_compile_features)
+
   # assume no resources building to test
   set(TEST_RESOURCES FALSE)
   # for windows and cygwin assume we have resources

Tests/CompileFeatures/CMakeLists.txt

@@ -3,6 +3,14 @@ cmake_minimum_required(VERSION 3.0)
 
 project(CompileFeatures)
 
+if (NOT CMAKE_CXX_COMPILE_FEATURES)
+  file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/dummy.cpp"
+    "int main(int,char**) { return 0; }\n"
+  )
+  add_executable(CompileFeatures "${CMAKE_CURRENT_BINARY_DIR}/dummy.cpp")
+  return()
+endif()
+
 macro(run_test feature)
   if (";${CMAKE_CXX_COMPILE_FEATURES};" MATCHES ${feature})
     add_library(test_${feature} OBJECT ${feature}.cpp)