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H.2 Documentation of Implementation Decisions
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
Implementation defined: Information
regarding bounded errors and erroneous execution.
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.
Discussion: Look up ``unspecified''
and ``erroneous execution'' in the index for a list of the cases.
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.
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
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