The CHECK_SINGLE_OPERATOR macro is used inside FOR_EACH_CREF macro, which, like all other FOR_EACH_* macros in Qt (see qdebug.h or qmetatype.h), expects its parameter to have a scope or a semicolon. All other CHECK_* macros are *not* used inside FOR_EACH_CREF, so they can follow a more traditional approach with the `do { } while (false)` scope without a trailing semicolon. This allows to use them in the code like: if (condition) MACRO(args); else OTHER_MACRO(args); In the example above, if MACRO ended with the semicolon, adding one more semicolon would have discarded the else part of the conditon, leading to compilation error. Amends bfb237d19a5319bfa020ad0cefaff72e8d94a9be. Task-number: QTBUG-119433 Pick-to: 6.7 Change-Id: I9a7f17416ba7c37a50f022f685b54e2643e4a9e2 Reviewed-by: Marc Mutz <marc.mutz@qt.io>