tests passed #37

src/runtime/common.rs

@@ -1,32 +1,48 @@
-use crate::runtime::traits::MinimallyRepresentableUInt;
+use crate::runtime::traits::{MinimallyRepresentableUInt, __private};
 use core::ops::Sub;
 
-use typenum::{Exp, U1, U16, U2, U256, U32, U4294967296, U64, U65536, U8};
+use typenum::{Exp, Unsigned, U1, U16, U2, U256, U32, U4294967296, U64, U65536, U8};
 
 impl MinimallyRepresentableUInt for U8 {
     type Type = u8;
     type UIntMaxValueAsType = <U256 as Sub<U1>>::Output;
     const MIN: Self::Type = Self::Type::MIN;
     const ONE: Self::Type = 1;
+
+    fn cast_unsigned_to_self_type<T: typenum::Unsigned>(_: __private::SealedToken) -> Self::Type {
+        <T as Unsigned>::U8
+    }
 }
 
 impl MinimallyRepresentableUInt for U16 {
     type Type = u16;
     type UIntMaxValueAsType = <U65536 as Sub<U1>>::Output;
     const MIN: Self::Type = Self::Type::MIN;
     const ONE: Self::Type = 1;
+
+    fn cast_unsigned_to_self_type<T: typenum::Unsigned>(_: __private::SealedToken) -> Self::Type {
+        <T as Unsigned>::U16
+    }
 }
 
 impl MinimallyRepresentableUInt for U32 {
     type Type = u32;
     type UIntMaxValueAsType = <U4294967296 as Sub<U1>>::Output;
     const MIN: Self::Type = Self::Type::MIN;
     const ONE: Self::Type = 1;
+
+    fn cast_unsigned_to_self_type<T: typenum::Unsigned>(_: __private::SealedToken) -> Self::Type {
+        <T as Unsigned>::U32
+    }
 }
 
 impl MinimallyRepresentableUInt for U64 {
     type Type = u64;
     type UIntMaxValueAsType = <Exp<U2, U64> as Sub<U1>>::Output;
     const MIN: Self::Type = Self::Type::MIN;
     const ONE: Self::Type = 1;
+
+    fn cast_unsigned_to_self_type<T: typenum::Unsigned>(_: __private::SealedToken) -> Self::Type {
+        <T as Unsigned>::U64
+    }
 }

src/runtime/secret.rs

@@ -1,7 +1,9 @@
 use core::{cell::UnsafeCell, marker::PhantomData, ops::Deref};
 
-use crate::runtime::{error, traits};
-use num_traits::{AsPrimitive, ConstOne};
+use crate::runtime::{
+    error,
+    traits::{self, __private},
+};
 use typenum::{IsLessOrEqual, True, Unsigned, U64};
 
 pub struct RTSecret<T, MEC: Unsigned, SIZE: traits::MinimallyRepresentableUInt = U64>(
@@ -71,8 +73,7 @@ impl<'secret, T, MEC: Unsigned, SIZE: traits::MinimallyRepresentableUInt>
         // SAFETY: All tuple fields of `RTSecret` are private, there are no setter to them.
         // `RTSecret` is also not `Sync` so it is not possible to have multithreading race condition.
         let ec_mut = unsafe { &mut *self.1.get() };
-        let ec_mut_usize: usize = ec_mut.as_();
-        if ec_mut_usize >= MEC::USIZE {
+        if *ec_mut >= SIZE::cast_unsigned_to_self_type::<MEC>(__private::SealedToken {}) {
             return Err(error::ExposeSecretError::ExposeMoreThanMaximallyAllow(
                 error::ExposeMoreThanMaximallyAllowError {
                     mec: MEC::USIZE,

src/runtime/traits.rs

@@ -1,10 +1,10 @@
 use core::{
+    cmp::PartialOrd,
     fmt::{Debug, Display},
     ops::AddAssign,
 };
 
 pub use crate::runtime::error;
-use num_traits::AsPrimitive;
 use typenum::Unsigned;
 
 pub trait RTExposeSecret<'secret, T, SIZE: MinimallyRepresentableUInt> {
@@ -24,9 +24,17 @@ pub trait RTExposeSecret<'secret, T, SIZE: MinimallyRepresentableUInt> {
         for<'brand> ClosureType: FnOnce(Self::Exposed<'brand>) -> ReturnType;
 }
 
-pub(crate) trait MinimallyRepresentableUInt: Unsigned {
-    type Type: AddAssign + AsPrimitive<usize> + Debug + Display;
+pub(crate) mod __private {
+
+    pub struct SealedToken {}
+}
+
+pub trait MinimallyRepresentableUInt: Unsigned {
+    // indeed, `u8`, `u16`, `u32` and `u64` all satisfy these bounds
+    type Type: AddAssign + PartialOrd + Debug + Display + Copy;
     type UIntMaxValueAsType;
     const MIN: Self::Type;
     const ONE: Self::Type;
+
+    fn cast_unsigned_to_self_type<T: Unsigned>(_: __private::SealedToken) -> Self::Type;
 }

tests/extern_bin_rt.rs

@@ -1,5 +1,5 @@
 use sosecrets_rs::{
-    prelude::typenum::{U0, U1, U2},
+    prelude::typenum::{U1, U2},
     runtime::{
         secret::{RTExposedSecret, RTSecret},
         traits::RTExposeSecret,