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Re: Fix sign extension in cpplex.c
- From: "Ulrich Weigand" <Ulrich dot Weigand at de dot ibm dot com>
- To: Andreas Jaeger <aj at suse dot de>
- Cc: Neil Booth <neil at daikokuya dot demon dot co dot uk>, gcc-patches at gcc dot gnu dot org
- Date: Wed, 6 Feb 2002 13:57:10 +0100
- Subject: Re: Fix sign extension in cpplex.c
Andreas Jaeger wrote:
>"Ulrich Weigand" <Ulrich.Weigand@de.ibm.com> writes:
>
>> Hmm, as it is supposed to test sign extension, maybe we should
>> simply add a
>>
>> /* { dg-options "-fsigned-char" } */
>>
>> to the test case?
>
>That shouldn't make a difference since the code already uses
>signed/unsigned explicitly:
> signed char c = '\xff';
> unsigned char d = '\xff';
It makes a difference in how the *constant* is interpreted:
with -fsigned-char, '\xff' is equivalent to -127, while with
-funsigned-char, '\xff' is equivalent to 255 ...
See section 6.4.4.4.10 of the standard: "If an integer character
constant contains a single character or escape sequence, its value
is the one that results when an object with type char whose value
is that of the single character or escape sequence is converted to
type int."
Mit freundlichen Gruessen / Best Regards
Ulrich Weigand
--
Dr. Ulrich Weigand
Linux for S/390 Design & Development
IBM Deutschland Entwicklung GmbH, Schoenaicher Str. 220, 71032 Boeblingen
Phone: +49-7031/16-3727 --- Email: Ulrich.Weigand@de.ibm.com