Ada Reference Manual (Ada 2022) — Legal Information

# 8.5.1 Object Renaming Declarations

1/5
An object_renaming_declaration is used to rename an object or value.

#### Syntax

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object_renaming_declaration ::=
defining_identifier [: [null_exclusion] subtype_mark] renames object_name
[aspect_specification];
| defining_identifier : access_definition renames object_name
[aspect_specification];

#### Name Resolution Rules

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The type of the object_name shall resolve to the type determined by the subtype_mark, if present. If no subtype_mark or access_definition is present, the expected type of the object_name is any type.
3.1/5
In the case where the type is defined by an access_definition, the type of the object_name shall resolve to an anonymous access type. If the anonymous access type is an access-to-object type, the type of the object_name shall have the same designated type as that of the access_definition. If the anonymous access type is an access-to-subprogram type, the type of the object_name shall have a designated profile that is type conformant with that of the access_definition.

#### Legality Rules

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The renamed entity shall be an object or value.
4.1/5
In the case where the type is defined by an access_definition, the type of the renamed entity and the type defined by the access_definition:
4.2/2
shall both be access-to-object types with statically matching designated subtypes and with both or neither being access-to-constant types; or
4.3/2
shall both be access-to-subprogram types with subtype conformant designated profiles.
4.4/5
For an object_renaming_declaration with a null_exclusion or an access_definition that has a null_exclusion, the subtype of the object_name shall exclude null. In addition, if the object_renaming_declaration occurs within the body of a generic unit G or within the body of a generic unit declared within the declarative region of generic unit G, then:
4.5/5
if the object_name statically denotes a generic formal object of mode in out of G, then the declaration of that object shall have a null_exclusion;
4.6/5
if the object_name statically denotes a call of a generic formal function of G, then the declaration of the result of that function shall have a null_exclusion.
4.7/5
In the case where the object_name is a qualified_expression with a nominal subtype S and whose expression is a name that denotes an object Q:
4.8/5
if S is an elementary subtype, then:
4.9/5
Q shall be a constant other than a dereference of an access type; or
4.10/5
the nominal subtype of Q shall be statically compatible with S; or
4.11/5
S shall statically match the base subtype of its type if scalar, or the first subtype of its type if an access type.
4.12/5
if S is a composite subtype, then Q shall be known to be constrained or S shall statically match the first subtype of its type.
5/5
The renamed entity shall not be a subcomponent that depends on discriminants of an object whose nominal subtype is unconstrained unless the object is known to be constrained. A slice of an array shall not be renamed if this restriction disallows renaming of the array.
5.1/5
In addition to the places where Legality Rules normally apply (see 12.3), these rules also apply in the private part of an instance of a generic unit.

#### Static Semantics

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An object_renaming_declaration declares a new view of the renamed entity whose properties are identical to those of the renamed view. Thus, the properties of the renamed entity are not affected by the renaming_declaration. In particular, its nominal subtype, whether it is a value or an object, its value if it is an object, and whether or not it is a constant, are unaffected; similarly, the constraints and other properties of its nominal subtype are not affected by renaming (any constraint implied by the subtype_mark or access_definition of the object_renaming_declaration is ignored).

#### Examples

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Example of renaming an object:
8
declare
L : Person renames Leftmost_Person; -- see 3.10.1
begin
L.Age := L.Age + 1;
end;
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Example of renaming a value:
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Uno renames One; -- see 3.3.2

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