Fix runtime error Date object

[batizdaniel]

This patch fixes #4704

JerryScript-DCO-1.0-Signed-off-by: Daniel Batiz daniel.batiz@h-lab.eu

[dbatyai]

This doesn't really fix the issue, new Date(-20000000, 0) will trigger the same behavior on the other branch.
On top of that, even though it no longer triggers an undefined behavior, the value can still overflow, for example new Date(200000000, 0) (one extra zero), which actually results in a valid date (incorrectly).

I think the best approach would be to clamp the input year so that it's not abnormally large. The valid year range is [-271821, 275760], so clamping to a slightly larger range than that should be enough, making sure that invalid year values remain invalid.

[ossy-szeged]

I think the best approach would be to clamp the input year so that it's not abnormally large. The valid year range is [-271821, 275760], so clamping to a slightly larger range than that should be enough, making sure that invalid year values remain invalid.

It's not as easy. We can't clamp the input year, because there is no restriction for the arguments of the Date constructor, only the output Date object should be in the allowed interval. for example new Date(-271822, 16) is valid Date, but new Date(-271822, 15) is invalid.

[dbatyai]

That's why I said clamping it to a slightly larger range. That will filter out abnormally large input values, that should be invalid regardless, then the rest will be handled by the conversion logic correctly without overflowing.

[ossy-szeged]

https://262.ecma-international.org/12.0/#eqn-DaysFromYear

The latest spec clarifies that we should handle year as mathematical value (Arbitrary real numbers, used as the default numeric type) and the result should be Number (double):
DayFromYear(y) = 𝔽(365 × (ℝ(y) - 1970) + floor((ℝ(y) - 1969) / 4) - floor((ℝ(y) - 1901) / 100) + floor((ℝ(y) - 1601) / 400))