Changes from code reviews

Author: justingrant

lib/calendar.ts

@@ -1459,9 +1459,9 @@ const helperHebrew: HelperPerCalendarImpl = ObjectAssign({}, helperSharedImpl as
       if (monthExtra) {
         const monthInfo = this.months[monthExtra];
         if (!monthInfo) throw new RangeError(`Unrecognized month from formatToParts: ${monthExtra}`);
-        month = (this.inLeapYear({ year }) ? monthInfo.leap : monthInfo.regular) as number;
+        month = this.inLeapYear({ year }) ? monthInfo.leap : monthInfo.regular;
       }
-      // if we're getting data from legacy Date, then `month` will always be present
+      // Because we're getting data from legacy Date, then `month` will always be present
       monthCode = this.getMonthCode(year, month as number);
       const result = { year, month, day, era: undefined as string | undefined, eraYear, monthCode };
       return result;

lib/ecmascript.ts

@@ -4780,8 +4780,8 @@ export function RoundDuration(
   // First convert time units up to days, if rounding to days or higher units.
   // If rounding relative to a ZonedDateTime, then some days may not be 24h.
   // TS doesn't know that `dayLengthNs` is only used if the unit is day or
-  // larger. This makes the cast below acceptable.
-  let dayLengthNs: JSBI = undefined as unknown as JSBI;
+  // larger. We'll cast away `undefined` when it's used lower down below.
+  let dayLengthNs: JSBI | undefined;
   if (unit === 'year' || unit === 'month' || unit === 'week' || unit === 'day') {
     nanoseconds = TotalDurationNanoseconds(0, hours, minutes, seconds, milliseconds, microseconds, nanosecondsParam, 0);
     let intermediate;
@@ -4847,9 +4847,12 @@ export function RoundDuration(
       // the duration. This lets us do days-or-larger rounding using BigInt
       // math which reduces precision loss.
       oneYearDays = MathAbs(oneYearDays);
-      const divisor = JSBI.multiply(JSBI.BigInt(oneYearDays), dayLengthNs);
+      // dayLengthNs is never undefined if unit is `day` or larger.
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      const divisor = JSBI.multiply(JSBI.BigInt(oneYearDays), dayLengthNs!);
       nanoseconds = JSBI.add(
-        JSBI.add(JSBI.multiply(divisor, JSBI.BigInt(years)), JSBI.multiply(JSBI.BigInt(days), dayLengthNs)),
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+        JSBI.add(JSBI.multiply(divisor, JSBI.BigInt(years)), JSBI.multiply(JSBI.BigInt(days), dayLengthNs!)),
         nanoseconds
       );
       const rounded = RoundNumberToIncrement(
@@ -4903,9 +4906,12 @@ export function RoundDuration(
         ({ relativeTo, days: oneMonthDays } = MoveRelativeDate(calendar, relativeTo, oneMonth));
       }
       oneMonthDays = MathAbs(oneMonthDays);
-      const divisor = JSBI.multiply(JSBI.BigInt(oneMonthDays), dayLengthNs);
+      // dayLengthNs is never undefined if unit is `day` or larger.
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      const divisor = JSBI.multiply(JSBI.BigInt(oneMonthDays), dayLengthNs!);
       nanoseconds = JSBI.add(
-        JSBI.add(JSBI.multiply(divisor, JSBI.BigInt(months)), JSBI.multiply(JSBI.BigInt(days), dayLengthNs)),
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+        JSBI.add(JSBI.multiply(divisor, JSBI.BigInt(months)), JSBI.multiply(JSBI.BigInt(days), dayLengthNs!)),
         nanoseconds
       );
       const rounded = RoundNumberToIncrement(
@@ -4933,9 +4939,12 @@ export function RoundDuration(
         ({ relativeTo, days: oneWeekDays } = MoveRelativeDate(calendar, relativeTo, oneWeek));
       }
       oneWeekDays = MathAbs(oneWeekDays);
-      const divisor = JSBI.multiply(JSBI.BigInt(oneWeekDays), dayLengthNs);
+      // dayLengthNs is never undefined if unit is `day` or larger.
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      const divisor = JSBI.multiply(JSBI.BigInt(oneWeekDays), dayLengthNs!);
       nanoseconds = JSBI.add(
-        JSBI.add(JSBI.multiply(divisor, JSBI.BigInt(weeks)), JSBI.multiply(JSBI.BigInt(days), dayLengthNs)),
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+        JSBI.add(JSBI.multiply(divisor, JSBI.BigInt(weeks)), JSBI.multiply(JSBI.BigInt(days), dayLengthNs!)),
         nanoseconds
       );
       const rounded = RoundNumberToIncrement(
@@ -4950,7 +4959,9 @@ export function RoundDuration(
       break;
     }
     case 'day': {
-      const divisor = dayLengthNs;
+      // dayLengthNs is never undefined if unit is `day` or larger.
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      const divisor = dayLengthNs!;
       nanoseconds = JSBI.add(JSBI.multiply(divisor, JSBI.BigInt(days)), nanoseconds);
       const rounded = RoundNumberToIncrement(
         nanoseconds,

lib/intrinsicclass.ts

@@ -96,13 +96,17 @@ export function MakeIntrinsicClass(
     });
   }
   for (const prop of Object.getOwnPropertyNames(Class)) {
-    const desc = Object.getOwnPropertyDescriptor(Class, prop) as PropertyDescriptor;
+    // we know that `prop` is present, so the descriptor is never undefined
+    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+    const desc = Object.getOwnPropertyDescriptor(Class, prop)!;
     if (!desc.configurable || !desc.enumerable) continue;
     desc.enumerable = false;
     Object.defineProperty(Class, prop, desc);
   }
   for (const prop of Object.getOwnPropertyNames(Class.prototype)) {
-    const desc = Object.getOwnPropertyDescriptor(Class.prototype, prop) as PropertyDescriptor;
+    // we know that `prop` is present, so the descriptor is never undefined
+    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+    const desc = Object.getOwnPropertyDescriptor(Class.prototype, prop)!;
     if (!desc.configurable || !desc.enumerable) continue;
     desc.enumerable = false;
     Object.defineProperty(Class.prototype, prop, desc);