From: Bruno Haible <bruno@clisp.org>
To: bug-gnulib@gnu.org
Cc: Bjarni Ingi Gislason <bjarniig@simnet.is>
Subject: Re: -funsigned-char
Date: Wed, 08 Feb 2023 01:21:43 +0100 [thread overview]
Message-ID: <3741171.Sf62SLZxhT@nimes> (raw)
In-Reply-To: <Y+LZ6hsjn2ZPN6tu@localhost>
Bjarni Ingi Gislason wrote:
> > ../../gnulib-tests/test-localeconv.c:53: assertion 'l->frac_digits == CHAR_MAX' failed
> > FAIL test-localeconv (exit status: 134)
> >
>
> l->frac_digits is 127 and CHAR_MAX is 255.
>
> This is due to the CFLAG "-funsigned-char"
When you connect a libc compiled for one ABI and a program compiled for a
different ABI (that's what -funsigned-char produces), you evidently get
breakage.
> which I always use having
> compiled "less", which produced a lot of warnings without this flag.
The way to fix the problems occurring because a program wants to view
their strings as 'unsigned char *' is
- NOT to use -funsigned-char, as you just have seen,
- NOT to cast pointers from 'char *' to 'unsigned char *' and vice
versa, because ultimately this leads to strict aliasing violations
in some places,
- BUT to cast individual 'char *' elements to 'unsigned char' right
after fetching them from the string. E.g.
if (isalnum ((unsigned char) *p))
Bruno
prev parent reply other threads:[~2023-02-08 0:22 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-06 1:17 FAIL in diffutils/gnulib-tests Bjarni Ingi Gislason
2023-02-06 1:28 ` Bruno Haible
2023-02-06 3:19 ` Bjarni Ingi Gislason
2023-02-06 18:28 ` Bruno Haible
2023-02-07 23:08 ` Bjarni Ingi Gislason
2023-02-08 0:21 ` Bruno Haible [this message]
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