Merge pull request #6078 from Hacker0x01/fix/issue-5391-type-discriminated-union

fix: improve DatePickerProps discriminated union type inference

Author: martijnrusschen

src/index.tsx

@@ -218,8 +218,8 @@ export type DatePickerProps = OmitUnion<
     ) => void;
   } & (
     | {
-        selectsRange?: never;
-        selectsMultiple?: never;
+        selectsRange?: false | undefined;
+        selectsMultiple?: false | undefined;
         formatMultipleDates?: never;
         onChange?: (
           date: Date | null,
@@ -230,7 +230,7 @@ export type DatePickerProps = OmitUnion<
       }
     | {
         selectsRange: true;
-        selectsMultiple?: never;
+        selectsMultiple?: false | undefined;
         formatMultipleDates?: never;
         onChange?: (
           date: [Date | null, Date | null],
@@ -240,7 +240,7 @@ export type DatePickerProps = OmitUnion<
         ) => void;
       }
     | {
-        selectsRange?: never;
+        selectsRange?: false | undefined;
         selectsMultiple: true;
         formatMultipleDates?: (
           dates: Date[],

src/test/multiple_selected_dates.test.tsx

@@ -14,10 +14,7 @@ describe("Multiple Dates Selected", function () {
     extraProps: Partial<
       Pick<
         DatePickerProps,
-        | "selectsMultiple"
-        | "shouldCloseOnSelect"
-        | "disabledKeyboardNavigation"
-        | "onSelect"
+        "shouldCloseOnSelect" | "disabledKeyboardNavigation" | "onSelect"
       >
     > &
       OmitUnion<
@@ -28,7 +25,9 @@ describe("Multiple Dates Selected", function () {
         | "disabledKeyboardNavigation"
         | "onSelect"
         | "selectsRange"
-      >,
+      > & {
+        selectsMultiple?: true;
+      },
   ) {
     return render(
       <DatePicker