LibJS: Implement MakeDay without using AK::years_to_days_since_epoch

Implementing years_to_days_since_epoch without a loop will be tricky.
The TimeFromYear AO gives a good enough approximation for MakeDay until
we figure that out.

1 files changed, 4 insertions, 1 deletions

diff --git a/Userland/Libraries/LibJS/Runtime/Date.cpp b/Userland/Libraries/LibJS/Runtime/Date.cpp
index a48c5c24c1..96706e5fb4 100644
--- a/Userland/Libraries/LibJS/Runtime/Date.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Date.cpp
@@ -341,7 +341,10 @@ Value make_day(GlobalObject& global_object, Value year, Value month, Value date)
     // 8. Find a finite time value t such that YearFromTime(t) is ym and MonthFromTime(t) is mn and DateFromTime(t) is 1𝔽; but if this is not possible (because some argument is out of range), return NaN.
     if (!AK::is_within_range<int>(ym) || !AK::is_within_range<int>(mn + 1))
         return js_nan();
-    auto t = days_since_epoch(static_cast<int>(ym), static_cast<int>(mn) + 1, 1) * Date::ms_per_day;
+
+    // FIXME: We are avoiding AK::years_to_days_since_epoch here because it is implemented by looping over
+    //        the range [1970, ym), which will spin for any time value with an extremely large year.
+    auto t = time_from_year(ym) + (day_of_year(static_cast<int>(ym), static_cast<int>(mn) + 1, 1) * Date::ms_per_day);
 
     // 9. Return Day(t) + dt - 1𝔽.
     return Value(day(static_cast<double>(t)) + dt - 1);