Ada 2012 Reference Manual

6.5.1 Nonreturning Procedures

Specifying aspect No_Return to have the value True indicates that a procedure cannot return normally; it may propagate an exception or loop forever.

Paragraphs 2 and 3 were moved to Annex J, “Obsolescent Features”.

Static Semantics

For a procedure or generic procedure, the following language-defined representation aspect may be specified:

No_Return

The type of aspect No_Return is Boolean. When aspect No_Return is True for an entity, the entity is said to be nonreturning.

If directly specified, the aspect_definition shall be a static expression. This aspect is never inherited; if not directly specified, the aspect is False.

If a generic procedure is nonreturning, then so are its instances. If a procedure declared within a generic unit is nonreturning, then so are the corresponding copies of that procedure in instances.

Legality Rules

Aspect No_Return shall not be specified for a null procedure nor an instance of a generic unit.

A return statement shall not apply to a nonreturning procedure or generic procedure.

A procedure shall be nonreturning if it overrides a dispatching nonreturning procedure. In addition to the places where Legality Rules normally apply (see 12.3), this rule applies also in the private part of an instance of a generic unit.

If a renaming-as-body completes a nonreturning procedure declaration, then the renamed procedure shall be nonreturning.

Paragraph 8 was deleted.

Dynamic Semantics

If the body of a nonreturning procedure completes normally, Program_Error is raised at the point of the call.

Examples

procedure Fail(Msg : String) -- raises Fatal_Error exception
with No_Return;
-- Inform compiler and reader that procedure never returns normally