3.11.1 Completions of Declarations
Declarations sometimes come in two parts.
A
declaration that requires a second part is said to
require completion.
The second part is called the
completion of
the declaration (and of the entity declared), and is either another declaration,
a body, or a
pragma.
A
body is a
body,
an
entry_body,
a
null_procedure_declaration
or an
expression_function_declaration
that completes another declaration, or a renaming-as-body (see
8.5.4).
Name Resolution Rules
A construct that can
be a completion is interpreted as the completion of a prior declaration
only if:
The declaration and the completion occur immediately
within the same declarative region;
If the declaration is overloadable, then the completion
either has a type-conformant profile, or is a
pragma.
Legality Rules
An implicit declaration shall not have a completion.
For any explicit declaration that is specified to
require completion, there shall be a corresponding explicit completion,
unless the declared entity is imported (see
B.1).
At most one completion is allowed for a given declaration.
Additional requirements on completions appear where each kind of completion
is defined.
A type is
completely defined
at a place that is after its full type definition (if it has one) and
after all of its subcomponent types are completely defined. A type shall
be completely defined before it is frozen (see
13.14
and
7.3).
NOTE 1 Completions are in principle
allowed for any kind of explicit declaration. However, for some kinds
of declaration, the only allowed completion is an implementation-defined
pragma, and implementations are not required to have any such pragmas.
NOTE 2 There are rules that prevent
premature uses of declarations that have a corresponding completion.
The Elaboration_Checks of
3.11 prevent such
uses at run time for subprograms, protected operations, tasks, and generic
units. The rules of
13.14, “
Freezing
Rules” prevent, at compile time, premature uses of other entities
such as private types and deferred constants.
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