Syntax:
pragma Short_Circuit_And_Or;
This configuration pragma causes the predefined AND and OR operators of type Standard.Boolean to have short-circuit semantics. That is, they behave like AND THEN and OR ELSE; the right-hand side is not evaluated if the left-hand side determines the result. This may be useful in the context of certification protocols requiring the use of short-circuited logical operators.
There is no requirement that all units in a partition use this option.
However, mixing of short-circuit and non-short-circuit semantics can be
confusing. Therefore, the recommended use is to put the pragma in a
configuration file that applies to the whole program. Alternatively, if
you have a legacy library that should not use this pragma, you can put
it in a separate library project that does not use the pragma.
In any case, fine-grained mixing of the different semantics is not
recommended. If pragma Short_Circuit_And_Or is specified, then it
is illegal to rename the predefined Boolean AND and OR, or to pass
them to generic formal functions; this corresponds to the fact that
AND THEN and OR ELSE cannot be renamed nor passed as generic formal
functions.
Note that this pragma has no effect on other logical operators – predefined operators of modular types, array-of-boolean types and types derived from Standard.Boolean, nor user-defined operators.
See also the pragma Unevaluated_Use_Of_Old and the restriction
No_Direct_Boolean_Operators, which may be useful in conjunction
with Short_Circuit_And_Or.