Panic on attempt to shift left with overflow in Hijri calculation

[hsivonen]

Steps to reproduce

Run

use icu_calendar::Calendar;
fn main() {
    let mut fields = icu_calendar::types::DateFields::default();
    fields.era = Some("ah");
    fields.era_year = Some(1600);
    fields.day = Some(12.try_into().unwrap());
    fields.ordinal_month = Some(30.try_into().unwrap());
    let mut options = icu_calendar::options::DateFromFieldsOptions::default();
    options.missing_fields_strategy = Some(icu_calendar::options::MissingFieldsStrategy::Ecma);
    let uaq = icu_calendar::cal::Hijri::new_umm_al_qura();
    let end = uaq.from_fields(fields, options).unwrap();
}

Actual results

thread 'main' panicked at /opt/Projects/icu4x/components/calendar/src/provider/hijri.rs:92:18:
attempt to shift left with overflow

[hsivonen]

I now see that I accidentally reversed day and month. It's still a bug that 30 as month wasn't rejected early and flowed all the way to a panic.

[hsivonen]

icu4x/components/calendar/src/calendar_arithmetic.rs

Line 397 in bd87e67

1..=C::days_in_provided_month(year, month),

should check for the month being in range and error out if not.

[sffc]

People keep finding things that are on my to-do list on #6790 (comment), namely better testing for constrain behavior for out-of-bounds values. :)

[Manishearth]

I already fixed this with #7042, see

icu4x/components/calendar/src/calendar_arithmetic.rs

Lines 280 to 295 in 7944dd4

	let constrained_month = range_check_with_overflow(
	month,
	"month",
	1..=C::months_in_provided_year(year),
	options.overflow.unwrap_or_default(),
	)?;
	Ok(Self::new_unchecked(
	year,
	constrained_month,
	range_check_with_overflow(
	day,
	"day",
	1..=C::days_in_provided_month(year, constrained_month),
	options.overflow.unwrap_or_default(),
	)?,
	))

I'm going to close this out with a regression test.

[Manishearth]

Given that the issue is already fixed, I am going to bump this from the milestone, but leave it open to track the merging of #7102