https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118398
--- Comment #9 from mauro russo <ing.russomauro at gmail dot com> --- ok, I would say that, for point (b), ยง13.5.2.2 [temp.constr.op] - p2 and p3: "2 A conjunction is a constraint taking two operands. To determine if a conjunction is satisfied, the satisfaction of the first operand is checked. If that is not satisfied, the conjunction is not satisfied. Otherwise, the conjunction is satisfied if and only if the second operand is satisfied." "3 A disjunction is a constraint taking two operands. To determine if a disjunction is satisfied, the satisfaction of the first operand is checked. If that is satisfied, the disjunction is satisfied. Otherwise, the disjunction is satisfied if and only if the second operand is satisfied." confirms your statement, together the note after Example 1 in part 4: "... the constraint sizeof(char) > 1 is not satisfied; the second operand is not checked for satisfaction." I will discuss somewhere else whether it may be better to add a note that ill-forming does not care if an operand constraint is not checked at all. Please, may you tell me what about my residual doubt on point (a) ?