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Annotated Ada Reference Manual (Ada 202x Draft 24)Legal Information
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13.12.1 Language-Defined Restrictions and Profiles

Static Semantics

1/2
{AI95-00257-01} The following restriction_identifiers are language defined (additional restrictions are defined in the Specialized Needs Annexes):
1.1/3
 {AI05-0241-1} No_Implementation_Aspect_Specifications

There are no implementation-defined aspects specified by an aspect_specification. This restriction applies only to the current compilation or environment, not the entire partition. 
1.a/3
Discussion: {AI05-0241-1} This restriction (as well as others below) applies only to the current compilation, because it is likely that the runtime (and possibly user-written low-level code) will need to use implementation-defined aspects. But a partition-wide restriction applies everywhere, including the runtime.
2/2
{AI95-00257-01} No_Implementation_Attributes

There are no implementation-defined attributes. This restriction applies only to the current compilation or environment, not the entire partition.
2.a/3
{AI05-0241-1}
2.1/3
 {AI05-0246-1} {AI05-0269-1} No_Implementation_Identifiers

There are no usage names that denote declarations with implementation-defined identifiers that occur within language-defined packages or instances of language-defined generic packages. Such identifiers can arise as follows:
2.2/3
The following language-defined packages and generic packages allow implementation-defined identifiers:
2.3/3
package System (see 13.7);
2.4/3
package Standard (see A.1);
2.5/3
package Ada.Command_Line (see A.15);
2.6/3
package Interfaces.C (see B.3);
2.7/3
package Interfaces.C.Strings (see B.3.1);
2.8/3
package Interfaces.C.Pointers (see B.3.2);
2.9/3
package Interfaces.COBOL (see B.4);
2.10/3
package Interfaces.Fortran (see B.5); 
2.11/3
The following language-defined packages contain only implementation-defined identifiers:
2.12/3
package System.Machine_Code (see 13.8);
2.13/3
package Ada.Directories.Information (see A.16);
2.14/3
nested Implementation packages of the Queue containers (see A.18.28-31);
2.15/3
package Interfaces (see B.2);
2.16/3
package Ada.Interrupts.Names (see C.3.2).
2.17/3
For package Standard, Standard.Long_Integer and Standard.Long_Float are considered language-defined identifiers, but identifiers such as Standard.Short_Short_Integer are considered implementation-defined.
2.18/3
This restriction applies only to the current compilation or environment, not the entire partition.
3/2
{AI95-00257-01} No_Implementation_Pragmas 

There are no implementation-defined pragmas or pragma arguments. This restriction applies only to the current compilation or environment, not the entire partition.
3.1/3
 {AI05-0242-1} No_Implementation_Units 

There is no mention in the context_clause of any implementation-defined descendants of packages Ada, Interfaces, or System. This restriction applies only to the current compilation or environment, not the entire partition.
4/3
{AI95-00368-01} {AI05-0229-1} No_Obsolescent_Features 

There is no use of language features defined in Annex J. It is implementation defined whether uses of the renamings of J.1 and of the pragmas of J.15 are detected by this restriction. This restriction applies only to the current compilation or environment, not the entire partition. 
4.a/2
Reason: A user could compile a rename like 
4.b/2
with Ada.Text_IO;
package Text_IO renames Ada.Text_IO;
4.c/2
Such a rename must not be disallowed by this restriction, nor should the compilation of such a rename be restricted by an implementation. Many implementations implement the renames of J.1 by compiling them normally; we do not want to require implementations to use a special mechanism to implement these renames.
4.d/3
{AI05-0229-1} The pragmas have the same functionality as the corresponding aspect (unlike the typical obsolescent feature), and rejecting them could be a significant portability problem for existing code. 
5/3
{AI95-00381-01} {AI05-0241-1} The following restriction_parameter_identifiers are language defined:
6/2
{AI95-00381-01} No_Dependence 

Specifies a library unit on which there are no semantic dependences.
6.1/3
 {AI05-0241-1} No_Specification_of_Aspect 

Identifies an aspect for which no aspect_specification, attribute_definition_clause, or pragma is given.
6.2/3
 {AI05-0272-1} No_Use_Of_Attribute 

Identifies an attribute for which no attribute_reference or attribute_definition_clause is given.
6.3/3
 {AI05-0272-1} No_Use_Of_Pragma 

Identifies a pragma which is not to be used.

Legality Rules

7/2
{AI95-00381-01} The restriction_parameter_argument of a No_Dependence restriction shall be a name; the name shall have the form of a full expanded name of a library unit, but need not denote a unit present in the environment.
7.a/2
Ramification: This name is not resolved. 
7.1/3
 {AI05-0241-1} The restriction_parameter_argument of a No_Specification_of_Aspect restriction shall be an identifier; this is an identifier specific to a pragma (see 2.8) and does not denote any declaration.
7.b/3
Ramification: This restriction_parameter_argument is not resolved as it is an identifier specific to a pragma. As for No_Dependence, there is no check that the aspect identifier is meaningful; it might refer to an implementation-defined aspect on one implementation, but nothing at all on another implementation. 
7.2/3
 {AI05-0272-1} The restriction_parameter_argument of a No_Use_Of_Attribute restriction shall be an identifier or one of the reserved words Access, Delta, Digits, Mod, or Range; this is an identifier specific to a pragma.
7.c/3
Ramification: This restriction_parameter_argument is not resolved as it is an identifier specific to a pragma. There is no check that the attribute identifier refers to a known attribute_designator; it might refer to an implementation-defined attribute on one implementation, but nothing at all on another implementation. 
7.3/3
 {AI05-0272-1} The restriction_parameter_argument of a No_Use_Of_Pragma restriction shall be an identifier or the reserved word Interface; this is an identifier specific to a pragma.
7.d/3
Ramification: This restriction_parameter_argument is not resolved as it is an identifier specific to a pragma. There is no check that the pragma identifier refers to a known pragma; it might refer to an implementation-defined pragma on one implementation, but nothing at all on another implementation. 

Post-Compilation Rules

8/3
{AI95-00381-01} {AI05-0241-1} No compilation unit included in the partition shall depend semantically on the library unit identified by the name of a No_Dependence restriction.
8.a/2
Ramification: There is no requirement that the library unit actually exist. One possible use of the pragma is to prevent the use of implementation-defined units; when the program is ported to a different compiler, it is perfectly reasonable that no unit with the name exist. 

Static Semantics

9/3
{AI05-0246-1} The following profile_identifier is language defined:
10/3
{AI05-0246-1} No_Implementation_Extensions 

11/3
{AI05-0246-1} For usage profile No_Implementation_Extensions, there shall be no profile_pragma_argument_associations.
12/3
{AI05-0246-1} The No_Implementation_Extensions usage profile is equivalent to the following restrictions: 
13/3
No_Implementation_Aspect_Specifications,
No_Implementation_Attributes,
No_Implementation_Identifiers,
No_Implementation_Pragmas,
No_Implementation_Units.

Extensions to Ada 95

13.a/2
{AI95-00257-01} {AI95-00368-01} Restrictions No_Implementation_Attributes, No_Implementation_Pragmas, and No_Obsolescent_Features are new.
13.b/2
{AI95-00381-01} Restriction No_Dependence is new. 

Extensions to Ada 2005

13.c/3
{AI05-0241-1} {AI05-0242-1} {AI05-0246-1} {AI05-0272-1} Restrictions No_Implementation_Aspect_Specifications, No_Implementation_Identifiers, No_Implementation_Units, No_Specification_of_Aspect, No_Use_of_Attribute, and No_Use_of_Pragma are new.
13.d/3
{AI05-0246-1} Profile No_Implementation_Extensions is new. 

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