6.4 General Comments About Autoscoping

Note that task autoscoping rules and autoscoping results could change in future releases. Also, the order that implicitly determined scoping rules and autoscoping rules are applied could change in future releases as well.

The programmer explicitly requests autoscoping with the _auto(list-of-variables) clause, or the default(_auto) clause.Specifying default(_auto) or _auto(list-of-variables) clause for a parallel construct doesn't imply that same clause applies to task constructs that are lexically or dynamically enclosed in the parallel construct.

When autoscoping a variable that does not have predetermined implicit scope, the compiler checks the use of the variable against the above rules in the given order. If a rule matches, the compiler will scope the variable according to the matching rule. If no rule matches, or if autoscoping cannot handle the variable (there are certain restrictions, described below), the compiler will scope the variable as SHARED and treat the parallel or task construct as if an IF (.FALSE.) or if(0) clause were specified.

There aregenerally two reasons why autoscoping fails. One is that the use of the variable does not match any of the rules. The other is that the source code is too complex for the compiler to do a sufficient analysis. Function calls, complicated array subscripts, memory aliasing, and user-implemented synchronizations are some typical causes.