11-104r1
To: J3
From: Nick Maclaren/Bill Long
Subject: Interop TR: bounds revisited
Date: 2011 February 17
Reference: N1838, 10-228



The minutes state that no action was to be taken on 10-228 at meeting
193, which is just as well, because I am afraid that it was erroneous.
The situation is significantly worse than it stated.

N1838 is complete enough to see how CFI_bounds_t is used, and so this
proposes a more radical solution.  In summary, the stride member should
be removed, as it achieves little useful purpose and would need a lot of
work to specify.

CFI_cdesc_to_bounds cannot return a useful value for the stride in many
cases.

CFI_associate also uses a bounds array, and needs to say that the stride
member is ignored.

Paper 11-123r2 deleted the CFI_cdesc_to_bounds function.

With the new set of functions proposed in 11-144, CFI_associate is
deleted and the bounds array is no longer needed for anything other
than CFI_allocate.  In that case, the stride member is not used.
However, it is perhaps simpler for programmers if we just change
CFI_allocate to have separate lower_bounds and upper_bounds arrays and
delete CFI_bounds_t entirely. Edits are provided to do that.


Edits to N1838:

[11:4-10] Delete 5.2.4 CFI_bounds_t {whole subclause}.

[14:Table 5.3] In Table 5.3, delete the entries for
CFI_INVALID_UPPER_BOUND and CFI_INVALID_STRIDE and their associated
Error descriptions.

[15:24] In the title line for 5.2.6.6 int CFI_allocate, replace "const
CFI_bounds_t bounds[]" with "const CFI_index_t lower_bounds[], const
CFI+index_t upper_bounds[]".

[15:29] Replace "The number of elements in the bounds array" with "The
number of elements in the lower_bounds and upper_bounds arrays shall be
equal and".

[15:30] Replace the sentence "The stride values are ignored and
assumed to be one." with "The lower_bounds and upper_bounds arrays
provide the lower bounds and upper bounds, respectively, for each
corresponding dimension of the array."

[15:32] Replace "supplied bounds" with "supplied lower and upper
bounds".