Make DateImpl a newtype instead of a type alias

src/naive/date.rs

@@ -30,8 +30,8 @@ use crate::{Datelike, Duration, Weekday};
 use super::internals::{self, DateImpl, Mdf, Of, YearFlags};
 use super::isoweek;
 
-const MAX_YEAR: i32 = internals::MAX_YEAR;
-const MIN_YEAR: i32 = internals::MIN_YEAR;
+const MAX_YEAR: i32 = internals::MAX_YEAR.get();
+const MIN_YEAR: i32 = internals::MIN_YEAR.get();
 
 /// A week represented by a [`NaiveDate`] and a [`Weekday`] which is the first
 /// day of the week.
@@ -229,7 +229,7 @@ impl NaiveDate {
         }
         debug_assert!(YearFlags::from_year(year).0 == flags.0);
         match Of::new(ordinal, flags) {
-            Some(of) => Some(NaiveDate { ymdf: (year << 13) | (of.inner() as DateImpl) }),
+            Some(of) => Some(NaiveDate { ymdf: DateImpl::new((year << 13) | of.inner() as i32) }),
             None => None, // Invalid: Ordinal outside of the nr of days in a year with those flags.
         }
     }
@@ -241,7 +241,7 @@ impl NaiveDate {
             return None; // Out-of-range
         }
         match mdf.to_of() {
-            Some(of) => Some(NaiveDate { ymdf: (year << 13) | (of.inner() as DateImpl) }),
+            Some(of) => Some(NaiveDate { ymdf: DateImpl::new((year << 13) | of.inner() as i32) }),
             None => None, // Non-existing date
         }
     }
@@ -1027,7 +1027,9 @@ impl NaiveDate {
     /// Does not check if the year flags match the year.
     #[inline]
     const fn with_of(&self, of: Of) -> NaiveDate {
-        NaiveDate { ymdf: (self.ymdf & !0b1_1111_1111_1111) | of.inner() as DateImpl }
+        NaiveDate {
+            ymdf: DateImpl::new((self.ymdf.get() & !0b1_1111_1111_1111) | of.inner() as i32),
+        }
     }
 
     /// Makes a new `NaiveDate` for the next calendar date.
@@ -1405,9 +1407,11 @@ impl NaiveDate {
     }
 
     /// The minimum possible `NaiveDate` (January 1, 262145 BCE).
-    pub const MIN: NaiveDate = NaiveDate { ymdf: (MIN_YEAR << 13) | (1 << 4) | 0o07 /*FE*/ };
+    pub const MIN: NaiveDate =
+        NaiveDate { ymdf: DateImpl::new((MIN_YEAR << 13) | (1 << 4) | 0o07) /*FE*/ };
     /// The maximum possible `NaiveDate` (December 31, 262143 CE).
-    pub const MAX: NaiveDate = NaiveDate { ymdf: (MAX_YEAR << 13) | (365 << 4) | 0o17 /*F*/ };
+    pub const MAX: NaiveDate =
+        NaiveDate { ymdf: DateImpl::new((MAX_YEAR << 13) | (365 << 4) | 0o17) /*F*/ };
 }
 
 impl Datelike for NaiveDate {
@@ -1423,7 +1427,7 @@ impl Datelike for NaiveDate {
     /// ```
     #[inline]
     fn year(&self) -> i32 {
-        self.ymdf >> 13
+        self.ymdf.get() >> 13
     }
 
     /// Returns the month number starting from 1.

src/naive/internals.rs

@@ -19,10 +19,21 @@ use crate::Weekday;
 use core::fmt;
 
 /// The internal date representation: `year << 13 | Of`
-pub(super) type DateImpl = i32;
+#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq, PartialOrd, Ord)]
+pub(super) struct DateImpl(i32);
 
-pub(super) const MAX_YEAR: DateImpl = i32::MAX >> 13;
-pub(super) const MIN_YEAR: DateImpl = i32::MIN >> 13;
+pub(super) const MAX_YEAR: DateImpl = DateImpl::new(i32::MAX >> 13);
+pub(super) const MIN_YEAR: DateImpl = DateImpl::new(i32::MIN >> 13);
+
+impl DateImpl {
+    pub(super) const fn new(val: i32) -> Self {
+        DateImpl(val)
+    }
+
+    pub(super) const fn get(&self) -> i32 {
+        self.0
+    }
+}
 
 /// The year flags (aka the dominical letter).
 ///
@@ -280,7 +291,7 @@ impl Of {
 
     pub(super) const fn from_date_impl(date_impl: DateImpl) -> Of {
         // We assume the value in the `DateImpl` is valid.
-        Of((date_impl & 0b1_1111_1111_1111) as u32)
+        Of((date_impl.get() & 0b1_1111_1111_1111) as u32)
     }
 
     #[inline]

src/naive/isoweek.rs

@@ -47,7 +47,7 @@ pub(super) fn iso_week_from_yof(year: i32, of: Of) -> IsoWeek {
         }
     };
     let flags = YearFlags::from_year(year);
-    IsoWeek { ywf: (year << 10) | (week << 4) as DateImpl | DateImpl::from(flags.0) }
+    IsoWeek { ywf: DateImpl::new((year << 10) | (week << 4) as i32 | flags.0 as i32) }
 }
 
 impl IsoWeek {
@@ -73,7 +73,7 @@ impl IsoWeek {
     /// ```
     #[inline]
     pub const fn year(&self) -> i32 {
-        self.ywf >> 10
+        self.ywf.get() >> 10
     }
 
     /// Returns the ISO week number starting from 1.
@@ -90,7 +90,7 @@ impl IsoWeek {
     /// ```
     #[inline]
     pub const fn week(&self) -> u32 {
-        ((self.ywf >> 4) & 0x3f) as u32
+        ((self.ywf.get() >> 4) & 0x3f) as u32
     }
 
     /// Returns the ISO week number starting from 0.
@@ -107,7 +107,7 @@ impl IsoWeek {
     /// ```
     #[inline]
     pub const fn week0(&self) -> u32 {
-        ((self.ywf >> 4) & 0x3f) as u32 - 1
+        ((self.ywf.get() >> 4) & 0x3f) as u32 - 1
     }
 }