[Bug string/30620] New: wcscmp bug on platforms with unsigned wchar_t

[Bug string/30620] New: wcscmp bug on platforms with unsigned wchar_t

[bruno at clisp dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30620

            Bug ID: 30620
           Summary: wcscmp bug on platforms with unsigned wchar_t
           Product: glibc
           Version: 2.28
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: string
          Assignee: unassigned at sourceware dot org
          Reporter: bruno at clisp dot org
  Target Milestone: ---

Created attachment 14956
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14956&action=edit
test case testt-wcscmp.c

When we have two wide-character strings such that wcscmp (input1, input2) < 0,
obviously we should have wcscmp (input2, input1) > 0. This is not the case on
glibc on platforms which have an unsigned 'wchar_t' type (such as aarch64).

On platforms with a signed 'wchar_t' type (such as alpha), there is no problem.

How to reproduce: On a Linux/aarch64 machine, such as gcc185.fsffrance.org, run
the attached program:
$ gcc test-wcscmp.c
$ ./a.out 

Expected behaviour: Successful termination.

Actual behaviour:
test-wcscmp.c:107: assertion 'wcscmp (input2, input1) > 0' failed
Aborted (core dumped)

The problematic source code appears to be in the file glibc/wcsmbs/wcscmp.c .

The function wcsncmp, OTOH, works fine.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug string/30620] wcscmp bug on platforms with unsigned wchar_t

[bruno at clisp dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30620

Bruno Haible <bruno at clisp dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|                            |aarch64-unknown-linux
              Build|                            |aarch64-unknown-linux
               Host|                            |aarch64-unknown-linux

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug string/30620] wcscmp bug on platforms with unsigned wchar_t

[bruno at clisp dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30620

--- Comment #1 from Bruno Haible <bruno at clisp dot org> ---
Likewise on 32-bit ARM platforms (arm*-unknown-linux).

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug string/30620] wcscmp bug on platforms with unsigned wchar_t

[schwab@linux-m68k.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30620

--- Comment #2 from Andreas Schwab <schwab@linux-m68k.org> ---
The cited paragraph only defines the relation of two wide characters, not
arbitrary wchar_t values.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug string/30620] wcscmp bug on platforms with unsigned wchar_t

[bruno at clisp dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30620

--- Comment #3 from Bruno Haible <bruno at clisp dot org> ---
(In reply to Andreas Schwab from comment #2)
> The cited paragraph only defines the relation of two wide characters, not
> arbitrary wchar_t values.

ISO C 17 § 3.7.3 specifies that every wchar_t value is a "wide character".

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug string/30620] wcscmp bug on platforms with unsigned wchar_t

[schwab@linux-m68k.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30620

--- Comment #4 from Andreas Schwab <schwab@linux-m68k.org> ---
No, it only says that every wide character is representable as a wchar_t value.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug string/30620] wcscmp bug on platforms with unsigned wchar_t

[bruno at clisp dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30620

--- Comment #5 from Bruno Haible <bruno at clisp dot org> ---
The musl libc people recognize that wcscmp has to work on arbitrary wchar_t
values:
http://git.musl-libc.org/cgit/musl/commit/?id=07616721f1fa6cb215ffbef23441cae80412484f
https://www.openwall.com/lists/musl/2023/01/06/3

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug string/30620] wcscmp bug on platforms with unsigned wchar_t

[schwab@linux-m68k.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30620

--- Comment #6 from Andreas Schwab <schwab@linux-m68k.org> ---
But that's only a QoI issue.  You cannot argue with the standard if it doesn't
say anything.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug string/30620] wcscmp bug on platforms with unsigned wchar_t

[joseph at codesourcery dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30620

--- Comment #7 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
I think the relevant wording is the general wording for wchar.h: 
"Arguments to the functions in this subclause may point to arrays 
containing wchar_t values that do not correspond to members of the 
extended character set. Such values shall be processed according to the 
specified semantics, except that it is unspecified whether an encoding 
error occurs if such a value appears in the format string [...]".

-- 
You are receiving this mail because:
You are on the CC list for the bug.