The following issue has been SUBMITTED.
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http://austingroupbugs.net/view.php?id=1197
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Reported By: shware_systems
Assigned To:
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Project: 1003.1(2016)/Issue7+TC2
Issue ID: 1197
Category: System Interfaces
Type: Omission
Severity: Objection
Priority: normal
Status: New
Name: Mark Ziegast
Organization: SHware Systems Dev.
User Reference:
Section: abs, imaxabs, labs, llabs
Page Number: p567 ff
Line Number: L19829 ff
Interp Status: ---
Final Accepted Text:
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Date Submitted: 2018-07-30 19:19 UTC
Last Modified: 2018-07-30 19:19 UTC
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Summary: Omission from 1108: LONG_MIN must be <= -2147483648
Description:
In the resolution to 1108, Note 4041, while twos-complement arithmetic is
adequate to describe how the result arises, it overlooks that from a
mathematical and set theory standpoint the operation is also a range error
for the *_MIN values, in that the "correct" result is outside the range
*_MIN to *_MAX. This should be indicated in errno with ERANGE, raise SIGFPE
with Code FPE_INTOVF if not masked, or both.
Given *_MIN and *_MAX are independent values (with constraints) in both the
C and POSIX <limits.h>, leaving the behavior completely undefined in the C
standard can be considered a defect. It should at least require ERANGE be
set, imo. Assuming a 24-bit width for short, SHORT_MIN could be -1000000
and SHORT_MAX still 32767 and this would be considered conforming, if
pretty asymmetric. This range error would be triggered for each value
between -1000000 and -32768 inclusive, not just -32768.
Note with this potential asymmetry EDOM errors should also be accounted
for, but the appropriate signal code, FPE_INTTRAP or FPE_INTDOM, is missing
from <signal.h>.
Desired Action:
>From #1108, Change for abs(), other interfaces with similar wording:
On P567 L19829 (abs), replace
If the result cannot be represented, the behavior is undefined.
with
<CX>If the result cannot be represented, the result shall be i,
unchanged, and errno shall be set to ERANGE.</CX><XSI> Additionally, the
function shall raise SIGFPE with code FPE_INTOVF after setting
errno.</XSI>
On P567 L19838 (abs), replace
In two's-complement representation, the absolute value of the negative
integer with largest magnitude {INT_MIN} might not be representable.
with
<CX>Since POSIX.1 requires a two's complement representation of int,
the absolute value of the negative integer with the largest magnitude
{INT_MIN} is always not representable; the rules of negation in two's
complement arithmetic ensure that {INT_MIN} is returned when the value is
-pow(2,{WORD_BIT}-1) but may produce positive trap representations for
values between {INT_MIN} and negative {INT_MAX} otherwise.</CX>
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Issue History
Date Modified Username Field Change
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2018-07-30 19:19 shware_systems New Issue
2018-07-30 19:19 shware_systems Name => Mark Ziegast
2018-07-30 19:19 shware_systems Organization => SHware Systems Dev.
2018-07-30 19:19 shware_systems Section => abs, imaxabs, labs,
llabs
2018-07-30 19:19 shware_systems Page Number => p567 ff
2018-07-30 19:19 shware_systems Line Number => L19829 ff
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