test-sprintf-posix and test-snprintf-posix test failures

[Collin Funk]

I see two similar test failures for test-sprintf-posix and
test-sprintf-posix on Fedora 40, gcc 14, glibc 2.39.

Using:

$ ./gnulib-tool --create-testdir --dir testdir sprintf-posix snprintf-posix
$ cd testdir
$ ./configure
$ make check

The following tests fail:

./../build-aux/test-driver: line 112: 128650 Aborted                 (core 
dumped) "$@" >> "$log_file" 2>&1
FAIL: test-snprintf-posix
PASS: test-snprintf
./../build-aux/test-driver: line 112: 128669 Aborted                 (core 
dumped) "$@" >> "$log_file" 2>&1
FAIL: test-sprintf-posix

backtrace from test-snprintf-posix:
======================================
#4  0x00000000004097a2 in test_function (my_snprintf=<optimized out>) at 
/home/collin/.local/src/gnulib/testdir/gltests/test-snprintf-posix.h:3196
        retval = 5
        buf = "12345\000EF"
        size = <optimized out>
        result = "a\000z 33\000    
33\000cwlthcnggomhnqgbsynfxjndfoctldsdihygdqrghvtdxanjnzstbpklsewtvbncwuvbkwmfcbdjrboewqnmnqubkvhvldwqnkjjlotyfnwgsesgwmdwpjeaxutsssuwzcglqwdksajtdozlxkxkyncsiypgxpibunhbwrmieaxurpnljihggggghi"...
        L_xyz = L"xyz"
======================================

The retval is incorrect here:

  { /* NUL character.  */
    int retval =
      my_snprintf (result, sizeof (result),
                   "a%lcz %d", (wint_t) L'\0', 33, 44, 55);
    /* ISO C had this wrong for decades.  ISO C 23 now corrects it, through
       this wording:
       "If an l length modifier is present, the wint_t argument is converted
        as if by a call to the wcrtomb function with a pointer to storage of
        at least MB_CUR_MAX bytes, the wint_t argument converted to wchar_t,
        and an initial shift state."  */
    ASSERT (memcmp (result, "a\0z 33\0", 6 + 1) == 0);
    ASSERT (retval == 6);
  }

backtrace from test-sprintf-posix:
======================================
#4  0x00000000004090cd in test_function (my_sprintf=<optimized out>) at 
/home/collin/.local/src/gnulib/testdir/gltests/test-sprintf-posix.h:3174
        retval = 5
        result = "a\000z 33\000    
33\000cwlthcnggomhnqgbsynfxjndfoctldsdihygdqrghvtdxanjnzstbpklsewtvbncwuvbkwmfcbdjrboewqnmnqubkvhvldwqnkjjlotyfnwgsesgwmdwpjeaxutsssuwzcglqwdksajtdozlxkxkyncsiypgxpibunhbwrmieaxurpnljihggggghi"...
        buf = "12345\000EF"
        L_xyz = L"xyz"
======================================

The reval is incorrect here:

  { /* NUL character.  */
    int retval =
      my_sprintf (result, "a%lcz %d", (wint_t) L'\0', 33, 44, 55);
    /* ISO C had this wrong for decades.  ISO C 23 now corrects it, through
       this wording:
       "If an l length modifier is present, the wint_t argument is converted
        as if by a call to the wcrtomb function with a pointer to storage of
        at least MB_CUR_MAX bytes, the wint_t argument converted to wchar_t,
        and an initial shift state."  */
    ASSERT (memcmp (result, "a\0z 33\0", 6 + 1) == 0);
    ASSERT (retval == 6);
  }

Just incase locale matters:

$ locale
LANG=en_US.UTF-8
LC_CTYPE="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_COLLATE="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_PAPER="en_US.UTF-8"
LC_NAME="en_US.UTF-8"
LC_ADDRESS="en_US.UTF-8"
LC_TELEPHONE="en_US.UTF-8"
LC_MEASUREMENT="en_US.UTF-8"
LC_IDENTIFICATION="en_US.UTF-8"
LC_ALL=

Collin