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* [Bug c/35908] New: Dubious charset conversions
@ 2008-04-11 15:21 neil at gcc dot gnu dot org
2008-04-11 16:59 ` [Bug c/35908] " joseph at codesourcery dot com
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: neil at gcc dot gnu dot org @ 2008-04-11 15:21 UTC (permalink / raw)
To: gcc-bugs
GCC accepts the following with -ansi -pedantic -Wall without diagnostics
#include <stdlib.h>
wchar_t z[] = L"a" "\xff";
GCC claims a default execution charset of UTF-8; presumably the default
execution wide character set is UTF-32. But "\xff" is a two-character narrow
execution character set string literal, with characters \xff \0, which is
invalid UTF-8 and so cannot be converted in a meaningful way to the execution
character set (whatever it is).
I would expect the above code to be rejected, or at least diagnosed.
--
Summary: Dubious charset conversions
Product: gcc
Version: 4.1.3
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: neil at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35908
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c/35908] Dubious charset conversions
2008-04-11 15:21 [Bug c/35908] New: Dubious charset conversions neil at gcc dot gnu dot org
@ 2008-04-11 16:59 ` joseph at codesourcery dot com
2008-04-12 4:40 ` neil at daikokuya dot co dot uk
2009-03-30 1:03 ` jsm28 at gcc dot gnu dot org
2 siblings, 0 replies; 4+ messages in thread
From: joseph at codesourcery dot com @ 2008-04-11 16:59 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from joseph at codesourcery dot com 2008-04-11 16:58 -------
Subject: Re: New: Dubious charset conversions
On Fri, 11 Apr 2008, neil at gcc dot gnu dot org wrote:
> GCC accepts the following with -ansi -pedantic -Wall without diagnostics
>
> #include <stdlib.h>
> wchar_t z[] = L"a" "\xff";
>
> GCC claims a default execution charset of UTF-8; presumably the default
> execution wide character set is UTF-32. But "\xff" is a two-character narrow
> execution character set string literal, with characters \xff \0, which is
> invalid UTF-8 and so cannot be converted in a meaningful way to the execution
> character set (whatever it is).
>
> I would expect the above code to be rejected, or at least diagnosed.
Accepting it as equivalent to L"a\xff" (generating a wide character L'a'
followed by one with value 0xff) seems in accordance with the principles
of N951, the relevant ones of which are implemented in GCC.
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n951.htm
http://gcc.gnu.org/ml/gcc-patches/2003-07/msg00532.html
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35908
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c/35908] Dubious charset conversions
2008-04-11 15:21 [Bug c/35908] New: Dubious charset conversions neil at gcc dot gnu dot org
2008-04-11 16:59 ` [Bug c/35908] " joseph at codesourcery dot com
@ 2008-04-12 4:40 ` neil at daikokuya dot co dot uk
2009-03-30 1:03 ` jsm28 at gcc dot gnu dot org
2 siblings, 0 replies; 4+ messages in thread
From: neil at daikokuya dot co dot uk @ 2008-04-12 4:40 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from neil at daikokuya dot co dot uk 2008-04-12 04:40 -------
Subject: Re: Dubious charset conversions
joseph at codesourcery dot com wrote:-
> > GCC accepts the following with -ansi -pedantic -Wall without diagnostics
> >
> > #include <stdlib.h>
> > wchar_t z[] = L"a" "\xff";
> >
> > GCC claims a default execution charset of UTF-8; presumably the default
> > execution wide character set is UTF-32. But "\xff" is a two-character narrow
> > execution character set string literal, with characters \xff \0, which is
> > invalid UTF-8 and so cannot be converted in a meaningful way to the execution
> > character set (whatever it is).
> >
> > I would expect the above code to be rejected, or at least diagnosed.
>
> Accepting it as equivalent to L"a\xff" (generating a wide character L'a'
> followed by one with value 0xff) seems in accordance with the principles
> of N951, the relevant ones of which are implemented in GCC.
>
> http://www.open-std.org/jtc1/sc22/wg14/www/docs/n951.htm
> http://gcc.gnu.org/ml/gcc-patches/2003-07/msg00532.html
Ah, I'd forgotten about that. That document does make much more
sense, thanks. However I think there are at least two things wrong
in "Principle 7"; I've mailed Clive about those. [The single byte
requirement cannot be fulfilled for Latin source charset to UTF-8
target, for example, and UCNs are escape sequences that typically
cannot be encoded as a single byte].
GCC should perhaps consider not creating invalid UTF-8 (i.e. no 5 or
6 bytes forms, or encodings of \ufffe \uffff etc.)
Please feel free to close this report.
Neil.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35908
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c/35908] Dubious charset conversions
2008-04-11 15:21 [Bug c/35908] New: Dubious charset conversions neil at gcc dot gnu dot org
2008-04-11 16:59 ` [Bug c/35908] " joseph at codesourcery dot com
2008-04-12 4:40 ` neil at daikokuya dot co dot uk
@ 2009-03-30 1:03 ` jsm28 at gcc dot gnu dot org
2 siblings, 0 replies; 4+ messages in thread
From: jsm28 at gcc dot gnu dot org @ 2009-03-30 1:03 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from jsm28 at gcc dot gnu dot org 2009-03-30 01:03 -------
As discussed, L"a\xff" is the correct interpretation, and the strings changes
in C++0x and C1x make that clear.
--
jsm28 at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution| |INVALID
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35908
^ permalink raw reply [flat|nested] 4+ messages in thread
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2008-04-11 15:21 [Bug c/35908] New: Dubious charset conversions neil at gcc dot gnu dot org
2008-04-11 16:59 ` [Bug c/35908] " joseph at codesourcery dot com
2008-04-12 4:40 ` neil at daikokuya dot co dot uk
2009-03-30 1:03 ` jsm28 at gcc dot gnu dot org
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