Re: Safety Critical Systems and Ada 95

[stt@houdini.camb.inmet.com (Tucker Taft)]

JP Thornley (jpt@diphi.demon.co.uk) wrote:

: ...
: It's important to realise that pragma Restrictions does not *impose* 
: that restriction on the code. ARM 13.12 says "A pragma Restrictions 
: expresses the user's intent to abide by certain restrictions." and if 
: the user breaks the restriction the program need not do anything about 
: it. [In fact I think the program becomes erroneous - which isn't really 
: very useful.]

Not quite.  

Any restriction whose violation can be detected at compile-time
or link-time is treated as an error by the compiler.  It is only
restrictions that are undetectable prior to run-time that can
result in erroneous execution upon violation.

This rule is indicated by RM 13.12(8) which says 

  ... a partition shall obey the restriction ...

The word "shall" here means that the compiler or the
linker is required to detect violation of the restriction.

Different rules may apply to particular restrictions, but
13.12(8) specifies the default rule.

: ...
: Phil Thornley
: | JP Thornley    EMail jpt@diphi.demon.co.uk                           |
: |                      phil.thornley@acm.org                           |

--
-Tucker Taft   stt@inmet.com   http://www.inmet.com/~stt/
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