Add panicking_sub to Uint64/Uint128/Uint256/Uint512

CHANGELOG.md

@@ -23,6 +23,8 @@ and this project adheres to
   `Uint512::add` ([#2092])
 - cosmwasm-std: Add `{CosmosMsg,SubMsg,Response}::change_custom` to change the
   custom message type ([#2099])
+- cosmwasm-std: Add `Uint{64,128,256,512}::panicking_sub` which is like the
+  `Sub` implementation but `const`.
 
 [#1983]: https://github.com/CosmWasm/cosmwasm/pull/1983
 [#2057]: https://github.com/CosmWasm/cosmwasm/pull/2057

packages/core/src/math/uint128.rs

@@ -263,6 +263,17 @@ impl Uint128 {
         Self(self.0.saturating_pow(exp))
     }
 
+    /// This is the same as [`Uint128::sub`] but const.
+    ///
+    /// Panics on overflow.
+    #[must_use = "this returns the result of the operation, without modifying the original"]
+    pub const fn panicking_sub(self, other: Self) -> Self {
+        match self.0.checked_sub(other.u128()) {
+            None => panic!("attempt to subtract with overflow"),
+            Some(diff) => Self(diff),
+        }
+    }
+
     #[must_use = "this returns the result of the operation, without modifying the original"]
     pub const fn abs_diff(self, other: Self) -> Self {
         Self(if self.0 < other.0 {
@@ -385,11 +396,7 @@ impl Sub<Uint128> for Uint128 {
     type Output = Self;
 
     fn sub(self, rhs: Self) -> Self {
-        Uint128(
-            self.u128()
-                .checked_sub(rhs.u128())
-                .expect("attempt to subtract with overflow"),
-        )
+        self.panicking_sub(rhs)
     }
 }
 forward_ref_binop!(impl Sub, sub for Uint128, Uint128);
@@ -1176,6 +1183,21 @@ mod tests {
         assert_eq!(a, Uint128::from(1u32));
     }
 
+    #[test]
+    fn uint128_panicking_sub_works() {
+        let a = Uint128::new(5);
+        let b = Uint128::new(3);
+        assert_eq!(a.panicking_sub(b), Uint128::new(2));
+    }
+
+    #[test]
+    #[should_panic(expected = "attempt to subtract with overflow")]
+    fn uint128_panicking_sub_panics_on_overflow() {
+        let a = Uint128::ZERO;
+        let b = Uint128::ONE;
+        let _diff = a.panicking_sub(b);
+    }
+
     #[test]
     fn uint128_abs_diff_works() {
         let a = Uint128::from(42u32);

packages/core/src/math/uint256.rs

@@ -335,6 +335,17 @@ impl Uint256 {
         Self(self.0.saturating_pow(exp))
     }
 
+    /// This is the same as [`Uint256::sub`] but const.
+    ///
+    /// Panics on overflow.
+    #[must_use = "this returns the result of the operation, without modifying the original"]
+    pub const fn panicking_sub(self, other: Self) -> Self {
+        match self.0.checked_sub(other.0) {
+            None => panic!("attempt to subtract with overflow"),
+            Some(diff) => Self(diff),
+        }
+    }
+
     #[must_use = "this returns the result of the operation, without modifying the original"]
     pub const fn abs_diff(self, other: Self) -> Self {
         Self(self.0.abs_diff(other.0))
@@ -455,11 +466,7 @@ impl Sub<Uint256> for Uint256 {
     type Output = Self;
 
     fn sub(self, rhs: Self) -> Self {
-        Self(
-            self.0
-                .checked_sub(rhs.0)
-                .expect("attempt to subtract with overflow"),
-        )
+        self.panicking_sub(rhs)
     }
 }
 forward_ref_binop!(impl Sub, sub for Uint256, Uint256);
@@ -1725,6 +1732,21 @@ mod tests {
         assert_eq!(a, Uint256::from(1u32));
     }
 
+    #[test]
+    fn uint256_panicking_sub_works() {
+        let a = Uint256::from(5u32);
+        let b = Uint256::from(3u32);
+        assert_eq!(a.panicking_sub(b), Uint256::from(2u32));
+    }
+
+    #[test]
+    #[should_panic(expected = "attempt to subtract with overflow")]
+    fn uint256_panicking_sub_panics_on_overflow() {
+        let a = Uint256::ZERO;
+        let b = Uint256::ONE;
+        let _diff = a.panicking_sub(b);
+    }
+
     #[test]
     fn uint256_abs_diff_works() {
         let a = Uint256::from(42u32);

packages/core/src/math/uint512.rs

@@ -298,6 +298,17 @@ impl Uint512 {
         Self(self.0.saturating_pow(exp))
     }
 
+    /// This is the same as [`Uint512::sub`] but const.
+    ///
+    /// Panics on overflow.
+    #[must_use = "this returns the result of the operation, without modifying the original"]
+    pub const fn panicking_sub(self, other: Self) -> Self {
+        match self.0.checked_sub(other.0) {
+            None => panic!("attempt to subtract with overflow"),
+            Some(diff) => Self(diff),
+        }
+    }
+
     #[must_use = "this returns the result of the operation, without modifying the original"]
     pub const fn abs_diff(self, other: Self) -> Self {
         Self(self.0.abs_diff(other.0))
@@ -434,7 +445,7 @@ impl Sub<Uint512> for Uint512 {
     type Output = Self;
 
     fn sub(self, rhs: Self) -> Self {
-        Uint512(self.0.checked_sub(rhs.0).unwrap())
+        self.panicking_sub(rhs)
     }
 }
 forward_ref_binop!(impl Sub, sub for Uint512, Uint512);
@@ -1370,6 +1381,21 @@ mod tests {
         assert_eq!(a, Uint512::from(1u32));
     }
 
+    #[test]
+    fn uint512_panicking_sub_works() {
+        let a = Uint512::from(5u32);
+        let b = Uint512::from(3u32);
+        assert_eq!(a.panicking_sub(b), Uint512::from(2u32));
+    }
+
+    #[test]
+    #[should_panic(expected = "attempt to subtract with overflow")]
+    fn uint512_panicking_sub_panics_on_overflow() {
+        let a = Uint512::ZERO;
+        let b = Uint512::ONE;
+        let _diff = a.panicking_sub(b);
+    }
+
     #[test]
     fn uint512_abs_diff_works() {
         let a = Uint512::from(42u32);

packages/core/src/math/uint64.rs

@@ -257,6 +257,17 @@ impl Uint64 {
         Self(self.0.saturating_pow(exp))
     }
 
+    /// This is the same as [`Uint64::sub`] but const.
+    ///
+    /// Panics on overflow.
+    #[must_use = "this returns the result of the operation, without modifying the original"]
+    pub const fn panicking_sub(self, other: Self) -> Self {
+        match self.0.checked_sub(other.u64()) {
+            None => panic!("attempt to subtract with overflow"),
+            Some(diff) => Self(diff),
+        }
+    }
+
     #[must_use = "this returns the result of the operation, without modifying the original"]
     pub const fn abs_diff(self, other: Self) -> Self {
         Self(if self.0 < other.0 {
@@ -358,11 +369,7 @@ impl Sub<Uint64> for Uint64 {
     type Output = Self;
 
     fn sub(self, rhs: Self) -> Self {
-        Uint64(
-            self.u64()
-                .checked_sub(rhs.u64())
-                .expect("attempt to subtract with overflow"),
-        )
+        self.panicking_sub(rhs)
     }
 }
 forward_ref_binop!(impl Sub, sub for Uint64, Uint64);
@@ -1090,6 +1097,21 @@ mod tests {
         assert_eq!(a, Uint64::from(1u32));
     }
 
+    #[test]
+    fn uint64_panicking_sub_works() {
+        let a = Uint64::new(5);
+        let b = Uint64::new(3);
+        assert_eq!(a.panicking_sub(b), Uint64::new(2));
+    }
+
+    #[test]
+    #[should_panic(expected = "attempt to subtract with overflow")]
+    fn uint64_panicking_sub_panics_on_overflow() {
+        let a = Uint64::ZERO;
+        let b = Uint64::ONE;
+        let _diff = a.panicking_sub(b);
+    }
+
     #[test]
     fn uint64_abs_diff_works() {
         let a = Uint64::from(42u32);