[SR-6303] Handle non-existing UCalendarDateFields without crashing

[sashabelonogov]

Resolves: SR-6303

Running this code:

let components = DateComponents(calendar: Calendar(identifier: .gregorian),
                                        timeZone: .current,
                                        era: 1,
                                        year: 2017,
                                        month: 11,
                                        day: 5,
                                        hour: 20,
                                        minute: 38,
                                        second: 11,
                                        nanosecond: 40)
        guard let date = Calendar(identifier: .gregorian).date(from: components) else {
           return
        }
        let recreatedComponents = Calendar(identifier: .gregorian).dateComponents(in: .current, from: date)

causes Thread 1: EXC_BAD_ACCESS (code=1, address=0x608a12c5cd78)
in: CFCalendar._CFCalendarComposeAbsoluteTimeV()
on the line: ucal_set(calendar->_cal, field, value);

After investigating the issue, I found out that -1 is returned for UCalendarDateFields for nanoseconds and quarter calendar components. Also, one typo for the “era” components type was found.

I tried to handle this issue without crashing by moving -1 one level higher and handling this case so nil would be assigned to the nanoseconds and quarter fields instead of crashing.

Please let me know what you think.

[parkera]

Is this a function of which version of ICU we're linking against?

[sashabelonogov]

@parkera it seems that 59.1 but even in the last one (60.1) there are no UCalendarDateFields for nanoseconds and quarter. The list of all available UCalendarDateFields of 60.1:

enum UCalendarDateFields {
     UCAL_ERA,
     UCAL_YEAR,
     UCAL_MONTH,
     UCAL_WEEK_OF_YEAR,
     UCAL_WEEK_OF_MONTH,
     UCAL_DATE,
     UCAL_DAY_OF_YEAR,
     UCAL_DAY_OF_WEEK,
     UCAL_DAY_OF_WEEK_IN_MONTH,
     UCAL_AM_PM,
     UCAL_HOUR,
     UCAL_HOUR_OF_DAY,
     UCAL_MINUTE,
     UCAL_SECOND,
     UCAL_MILLISECOND,
     UCAL_ZONE_OFFSET,
     UCAL_DST_OFFSET,
     UCAL_YEAR_WOY,
     UCAL_DOW_LOCAL,
     UCAL_EXTENDED_YEAR,
     UCAL_JULIAN_DAY, 
     UCAL_MILLISECONDS_IN_DAY,
     UCAL_IS_LEAP_MONTH,
       /* Do not conditionalize the following with #ifndef U_HIDE_DEPRECATED_API,
        * it is needed for layout of Calendar, DateFormat, and other objects */
     UCAL_FIELD_COUNT,
     UCAL_DAY_OF_MONTH=UCAL_DATE
   };

I'm sorry if I understood something wrong.

[parkera]

I think you're correct, the quarter implementation in ICU has been a problem for some time.

[parkera]

Good catch on this one

[alblue]

@swift-ci please test

[alblue]

@swift-ci please test and merge

[alblue]

There have been conflicts added since we tried to merge this last time (maybe because of the drop by @phausler recently). Can you rebase your original change onto master please and resubmit?

[sashabelonogov]

@alblue I checked and the issue still persists after the High Sierra changes applied, so I rebased the changes. Thank you for reminding!

[ianpartridge]

@swift-ci please test and merge