Update: Using C++26 with contracts enabled

cmake/CourseExercise.cmake

@@ -21,7 +21,7 @@ function(add_course_exercise)
     endif()
 
     if(NOT EXERCISE_STANDARD)
-        set(EXERCISE_STANDARD 23)
+        set(EXERCISE_STANDARD 26)
     endif()
 
     set(target_name "${EXERCISE_MODULE}_${EXERCISE_NAME}")
@@ -33,6 +33,11 @@ function(add_course_exercise)
             "${CMAKE_CURRENT_SOURCE_DIR}/include"
     )
     course_set_cxx_standard(${target_name} ${EXERCISE_STANDARD})
+
+    if(EXERCISE_STANDARD GREATER_EQUAL 26)
+        course_enable_contracts(${target_name})
+    endif()
+
     course_apply_warnings(${target_name})
 
     if(COURSE_BUILD_TESTS)