Ada Reference Manual — Legal Information

6.5.1 Pragma No_Return

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A pragma No_Return indicates that a procedure cannot return normally; it may propagate an exception or loop forever.

Syntax

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The form of a pragma No_Return, which is a representation pragma (see 13.1), is as follows:

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pragma No_Return(procedure_local_name{, procedure_local_name});

Legality Rules

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Each procedure_local_name shall denote one or more procedures or generic procedures; the denoted entities are non-returning. The procedure_local_name shall not denote a null procedure nor an instance of a generic unit.

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A return statement shall not apply to a non-returning procedure or generic procedure.

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A procedure shall be non-returning if it overrides a dispatching non-returning 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.

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

Static Semantics

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

Dynamic Semantics

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

Examples

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