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 freezing rules (see
13.14) prevent,
at compile time, premature uses of other entities such as private types
and deferred constants.
Ada 2005 and 2012 Editions sponsored in part by Ada-Europe
