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H.2 Documentation of Implementation Decisions
Documentation Requirements
1
{unspecified [partial]}
The implementation shall document the range of effects for
each situation that the language rules identify as either a bounded error or
as having an unspecified effect. If the implementation can constrain the effects
of erroneous execution for a given construct, then it shall document such constraints.
[The documentation might be provided either independently of any compilation
unit or partition, or as part of an annotated listing for a given unit or partition.
See also
1.1.3, and
1.1.2.]
1.a
Implementation defined: Information
regarding bounded errors and erroneous execution.
2
5 Among the situations to
be documented are the conventions chosen for parameter passing, the methods
used for the management of run-time storage, and the method used to evaluate
numeric expressions if this involves extended range or extra precision.
2.a
Discussion: Look up ``unspecified''
and ``erroneous execution'' in the index for a list of the cases.
2.b
The management of run-time storage
is particularly important. For safety applications, it is often necessary
to show that a program cannot raise Storage_Error, and for security applications
that information cannot leak via the run-time system. Users are likely
to prefer a simple storage model that can be easily validated.
2.c
The documentation could helpfully take
into account that users may well adopt a subset to avoid some forms of erroneous
execution, for instance, not using the abort statement, so that the effects
of a partly completed assignment_statement
do not have to be considered in the validation of a program (see 9.8).
For this reason documentation linked to an actual compilation may be most useful.
Similarly, an implementation may be able to take into account use of the Restrictions
pragma.
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