7 Expressions [expr]

7.6 Compound expressions [expr.compound]

7.6.15 Logical OR operator [expr.log.or]

The || operator groups left-to-right.
The operands are both contextually converted to bool.
The result is true if either of its operands is true, and false otherwise.
Unlike |, || guarantees left-to-right evaluation; moreover, the second operand is not evaluated if the first operand evaluates to true.
The result is a bool.
If the second expression is evaluated, the first expression is sequenced before the second expression ([intro.execution]).