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C.5 Pragma Discard_Names

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A pragma Discard_Names may be used to request a reduction in storage used for the names of certain entities. 

Syntax

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The form of a pragma Discard_Names is as follows: 
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  pragma Discard_Names[([On => ] local_name)];
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A pragma Discard_Names is allowed only immediately within a declarative_part, immediately within a package_specification, or as a configuration pragma.

Legality Rules

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The local_name (if present) shall denote a non-derived enumeration first subtype, a tagged first subtype, or an exception. The pragma applies to the type or exception. Without a local_name, the pragma applies to all such entities declared after the pragma, within the same declarative region. Alternatively, the pragma can be used as a configuration pragma. If the pragma applies to a type, then it applies also to all descendants of the type. 

Static Semantics

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If a local_name is given, then a pragma Discard_Names is a representation pragma.
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If the pragma applies to an enumeration type, then the semantics of the Wide_Wide_Image and Wide_Wide_Value attributes are implementation defined for that type; the semantics of Image, Wide_Image, Value, and Wide_Value are still defined in terms of Wide_Wide_Image and Wide_Wide_Value. In addition, the semantics of Text_IO.Enumeration_IO are implementation defined. If the pragma applies to a tagged type, then the semantics of the Tags.Wide_Wide_Expanded_Name function are implementation defined for that type; the semantics of Tags.Expanded_Name and Tags.Wide_Expanded_Name are still defined in terms of Tags.Wide_Wide_Expanded_Name. If the pragma applies to an exception, then the semantics of the Exceptions.Wide_Wide_Exception_Name function are implementation defined for that exception; the semantics of Exceptions.Exception_Name and Exceptions.Wide_Exception_Name are still defined in terms of Exceptions.Wide_Wide_Exception_Name.

Implementation Advice

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If the pragma applies to an entity, then the implementation should reduce the amount of storage used for storing names associated with that entity. 

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