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ID |
Category |
Severity |
Type |
Date Submitted |
Last Update |
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0001177 |
[1003.1(2016/18)/Issue7+TC2] Base Definitions and Headers |
Objection |
Error |
2017-12-16 05:26 |
2019-02-14 17:07 |
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Reporter |
shware_systems |
View Status |
public |
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Assigned To |
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Priority |
normal |
Resolution |
Duplicate |
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Status |
Closed |
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Name |
Mark Ziegast |
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Organization |
SHware Systems Dev. |
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User Reference |
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Section |
XBD 13, <stdint.h> |
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Page Number |
348 |
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Line Number |
11817-8 |
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Interp Status |
--- |
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Final Accepted Text |
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Summary |
0001177: Misstated permitted limits on signed types |
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Description |
The sentence:
An N-bit signed type has values in the range −2^(N−1) or 1−2^(N−1) to
2^(N−1)−1, while an N-bit unsigned type has values in the range 0 to 2^N−1.
is in error. Because POSIX requires int8, 16, and 32_t types be defined, for the least, fast, and built-in types to have equivalent ranges for the required compilation environments the 1-2^(N-1) limit is not permitted. That limit, while implied as usable by the C standard, is for environments that don't define the exact width types because they use -2^(N-1) as a trap value or as a negative zero. |
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Desired Action |
Delete the sentence and append to Line 11814:
For the required compilation environments (Xref c99 Extended Description) an N-bit signed type has values in the range −2^(N−1) to 2^(N−1)−1, while an N-bit unsigned type has values in the range 0 to 2^N−1. An implementation may support additional compilation environments where the minimum value for a signed type may be 1-2^(N-1), but these shall not define via typedef the exact width types below.
and shade this CX, as it is an expression of behavior the C standard considers implementation-defined, per c99/c1x 6.2.6.2, par 2. This makes normative the Rationale assertions in <stdint.h> and XRAT A.3 that two's complement is required.
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