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Fix *_DAYS_FROM_YEAR_0 calculation #1312

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Merged
merged 2 commits into from
Sep 25, 2023
Merged

Fix *_DAYS_FROM_YEAR_0 calculation #1312

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6f4a6b5
Fix *_DAYS_FROM_YEAR_0 calculation
pitdicker May 4, 2023
913c502
Also report correct ordinal in `test_date_bounds`
pitdicker May 19, 2023
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27 changes: 11 additions & 16 deletions src/naive/date.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2405,13 +2405,14 @@ mod tests {
let calculated_max = NaiveDate::from_ymd_opt(MAX_YEAR, 12, 31).unwrap();
assert!(
NaiveDate::MIN == calculated_min,
"`NaiveDate::MIN` should have a year flag {:?}",
"`NaiveDate::MIN` should have year flag {:?}",
calculated_min.of().flags()
);
assert!(
NaiveDate::MAX == calculated_max,
"`NaiveDate::MAX` should have a year flag {:?}",
calculated_max.of().flags()
"`NaiveDate::MAX` should have year flag {:?} and ordinal {}",
calculated_max.of().flags(),
calculated_max.of().ordinal()
);

// let's also check that the entire range do not exceed 2^44 seconds
Expand Down Expand Up @@ -3235,22 +3236,16 @@ mod tests {
}

// MAX_YEAR-12-31 minus 0000-01-01
// = ((MAX_YEAR+1)-01-01 minus 0001-01-01) + (0001-01-01 minus 0000-01-01) - 1 day
// = ((MAX_YEAR+1)-01-01 minus 0001-01-01) + 365 days
// = MAX_YEAR * 365 + (# of leap years from 0001 to MAX_YEAR) + 365 days
// = (MAX_YEAR-12-31 minus 0000-12-31) + (0000-12-31 - 0000-01-01)
// = MAX_YEAR * 365 + (# of leap years from 0001 to MAX_YEAR) + 365
// = (MAX_YEAR + 1) * 365 + (# of leap years from 0001 to MAX_YEAR)
const MAX_DAYS_FROM_YEAR_0: i32 =
MAX_YEAR * 365 + MAX_YEAR / 4 - MAX_YEAR / 100 + MAX_YEAR / 400 + 365;
(MAX_YEAR + 1) * 365 + MAX_YEAR / 4 - MAX_YEAR / 100 + MAX_YEAR / 400;

// MIN_YEAR-01-01 minus 0000-01-01
// = (MIN_YEAR+400n+1)-01-01 minus (400n+1)-01-01
// = ((MIN_YEAR+400n+1)-01-01 minus 0001-01-01) - ((400n+1)-01-01 minus 0001-01-01)
// = ((MIN_YEAR+400n+1)-01-01 minus 0001-01-01) - 146097n days
//
// n is set to 1000 for convenience.
const MIN_DAYS_FROM_YEAR_0: i32 = (MIN_YEAR + 400_000) * 365 + (MIN_YEAR + 400_000) / 4
- (MIN_YEAR + 400_000) / 100
+ (MIN_YEAR + 400_000) / 400
- 146_097_000;
// = MIN_YEAR * 365 + (# of leap years from MIN_YEAR to 0000)
const MIN_DAYS_FROM_YEAR_0: i32 =
MIN_YEAR * 365 + MIN_YEAR / 4 - MIN_YEAR / 100 + MIN_YEAR / 400;

// only used for testing, but duplicated in naive::datetime
const MAX_BITS: usize = 44;
Expand Down