The presence of a SUPPRESS pragma gives permission to an implementation to omit certain run-time checks. The form of this pragma is as follows:
pragma SUPPRESS(identifier [, [ON =>] name]);
The identifier is that of the check that can be omitted. The name (if present) must be either a simple name or an expanded name and it must denote either an object, a type or subtype, a task unit, or a generic unit; alternatively the name can be a subprogram name, in which case it can stand for several visible overloaded subprograms.
A pragma SUPPRESS is only allowed immediately within a declarative part or immediately within a package specification. In the latter case, the only allowed form is with a name that denotes an entity (or several overloaded subprograms) declared immediately within the package specification. The permission to omit the given check extends from the place of the pragma to the end of the declarative region associated with the innermost enclosing block statement or program unit. For a pragma given in a package specification, the permission extends to the end of the scope of the named entity.
If the pragma includes a name, the permission to omit the given check is further restricted: it is given only for operations on the named object or on all objects of the base type of a named type or subtype; for calls of a named subprogram; for activations of tasks of the named task type; or for instantiations of the given generic unit.
The following checks correspond to situations in which the exception CONSTRAINT_ERROR may be raised; for these checks, the name (if present) must denote either an object or a type.
The following checks correspond to situations in which the exception NUMERIC_ERROR is raised. The only allowed names in the corresponding pragmas are names of numeric types.
The following check corresponds to situations in which the exception PROGRAM_ERROR is raised. The only allowed names in the corresponding pragmas are names denoting task units, generic units, or subprograms.
The following check corresponds to situations in which the exception STORAGE_ERROR is raised. The only allowed names in the corresponding pragmas are names denoting access types, task units, or subprograms.
If an error situation arises in the absence of the corresponding run-time checks, the execution of the program is erroneous (the results are not defined by the language).
pragma SUPPRESS(RANGE_CHECK); pragma SUPPRESS(INDEX_CHECK, ON => TABLE);
For certain implementations, it may be impossible or too costly to suppress certain checks. The corresponding SUPPRESS pragma can be ignored. Hence, the occurrence of such a pragma within a given unit does not guarantee that the corresponding exception will not arise; the exceptions may also be propagated by called units.
References: access type 3.8, access value 3.8, activation 9.3, aggregate 4.3, allocator 4.8, array 3.6, attribute 4.1.4, block statement 5.6, collection 3.8, compatible 3.3.2, component of an array 3.6, component of a record 3.7, composite type 3.3, constraint 3.3, constraint_error exception 11.1, declarative part 3.9, designate 3.8, dimension 3.6, discrete range 3.6, discriminant 3.7.1, discriminant constraint 3.7.2, elaboration 3.1 3.9, erroneous 1.6, error situation 11, expanded name 4.1.3, generic body 11.1, generic instantiation 12.3, generic unit 12, identifier 2.3, index 3.6, index constraint 3.6.1, indexed component 4.1.1, null access value 3.8, numeric operation 3.5.5 3.5.8 3.5.10, numeric type 3.5, numeric_error exception 11.1, object 3.2, operation 3.3.3, package body 7.1, package specification 7.1, pragma 2.8, program_error exception 11.1, program unit 6, propagation of an exception 11.4, range constraint 3.5, record type 3.7, simple name 4.1, slice 4.1.2, subprogram 6, subprogram body 6.3, subprogram call 6.4, subtype 3.3, subunit 10.2, task 9, task body 9.1, task type 9.1, task unit 9, type 3.3, type mark 3.3.2
Rationale references: 14.2.6 Suppressing Checks, 14.5.3 Suppression of Checks,
Style Guide references: 5.9.5 Suppression of Exception Check
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