strftime() broken for "c" and "X" specifiers.

[bipolar]

Found while analyzing Python's test suite results for test_strptime.py.

(same results on beta4 and on hrev567104, both 64 bits)

The following minimal code:

import time

time_tuple = time.struct_time((1999,3,17,22,44,55,2,76,0))

# Specifiers' list from:
# https://pubs.opengroup.org/onlinepubs/9699919799/functions/strptime.html
for c in 'aAbBcCdDehHIjmMnprRStTUwWxXyY%':
    print('Testing "%s": "%s"' % (c, time.strftime('%' + c, time_tuple)))

prints correct values for all specifiers except for "c" and "X", as on Haiku I get:

Testing "c": ""
Testing "X": ""

For comparison, on both Win10 and Linux I get:

Testing "c": "Wed Mar 17 22:44:55 1999"
Testing "X": "22:44:55"

As far as I can tell, time.strftime() is basically just calling the system's strftime() on Haiku/Linux (and wcsftime on Win).

On the seemingly related #17884 davidkaroly said that wxWidgets was also affected and:

"most likely %c, %x, %X are impacted."

Not sure if he still sees the same there.

Seems to me that nl_strftime() is not producing correct results for D_T_FMT (%c) and T_FMT (%X), but works fine for T_FMT_AMPM (%r) and D_FMT (%x).

(That is as far as I can go :-/)

[bipolar]

Re-checking the output of the script above, noticed that "%x" also shows differences:

On Haiku:

Testing "x": "Mar 17, 1999"

On Linux and Win10:

Testing "x": "03/17/99"

[bipolar]

Updating the test case to:

#include <clocale>
#include <ctime>
#include <cstdio>
#include <cstring>

void dotest()
{
    // Python's test data: {1999, 3, 17, 22, 44, 55, 2, 76, 0}
    struct tm time = {55, 44, 22, 17, 2, 99, 3, 75, 0};
    const char specifiers[] = "aAbBcCdDehHIjmMnprRStTUwWxXyY%";

    for (int i=0; i < strlen(specifiers); i++) {
        char fmt[3] = {};
        char buffer[80] = {};

        sprintf(fmt, "%%%c", specifiers[i]);
        strftime(buffer, 80, fmt, &time);

        printf("Testing '%c': '%s'\n", specifiers[i], buffer);
    }
}


int main(void)
{
    puts("Testing with default locale:");
    dotest();

    puts("Testing after: setlocale(LC_TIME, \"es_AR.utf8\")");
    setlocale(LC_TIME, "es_AR.utf8");
    dotest();
}

Shows an empty value for %c after setting the locale to es_AR.utf8 (same as talked here and subsequent comments).

So, I guess I might have tested with different locales, and that's why I was getting different results.

%X specifier looks fine tho, so that might be an issue on our Python's port side.