Add FromPrimitiveWithConfig trait.

src/field.rs

@@ -163,8 +163,41 @@ where
     }
 }
 
+/// The trait combines all `FromWithConfig<u*>` and `FromWithConfig<i*>` into
+/// one umbrella trait. Handy when one needs conversion functions for different
+/// primitive int types.
+pub trait FromPrimitiveWithConfig:
+    FromWithConfig<u8>
+    + FromWithConfig<u16>
+    + FromWithConfig<u32>
+    + FromWithConfig<u64>
+    + FromWithConfig<u128>
+    + FromWithConfig<i8>
+    + FromWithConfig<i16>
+    + FromWithConfig<i32>
+    + FromWithConfig<i64>
+    + FromWithConfig<i128>
+{
+}
+
+/// Blanket implementation.
+impl<
+    T: FromWithConfig<u8>
+        + FromWithConfig<u16>
+        + FromWithConfig<u32>
+        + FromWithConfig<u64>
+        + FromWithConfig<u128>
+        + FromWithConfig<i8>
+        + FromWithConfig<i16>
+        + FromWithConfig<i32>
+        + FromWithConfig<i64>
+        + FromWithConfig<i128>,
+> FromPrimitiveWithConfig for T
+{
+}
+
 /// Analogous to `Into` trait, but with a prime field configuration parameter.
-/// Preferribly should not be implemented directly.
+/// Preferably should not be implemented directly.
 pub trait IntoWithConfig<F: PrimeField> {
     fn into_with_cfg(self, cfg: &F::Config) -> F;
 }

src/field/ark_ff_fp.rs

@@ -724,6 +724,7 @@ mod tests {
     #[test]
     fn ensure_blanket_traits() {
         ensure_type_implements_trait!(F, ConstIntRing);
+        ensure_type_implements_trait!(F, FromPrimitiveWithConfig);
     }
 
     #[test]

src/field/crypto_bigint_boxed_monty.rs

@@ -472,12 +472,19 @@ impl PrimeField for BoxedMontyField {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::ensure_type_implements_trait;
     use alloc::vec;
     use crypto_bigint::BoxedUint;
     use num_traits::Pow;
 
     type F = BoxedMontyField;
 
+    #[test]
+    fn ensure_blanket_traits() {
+        // NB: this ensures `PrimeField` implementation too!
+        ensure_type_implements_trait!(F, FromPrimitiveWithConfig);
+    }
+
     //
     // Test helpers
     //

src/field/crypto_bigint_const_monty.rs

@@ -687,7 +687,8 @@ mod tests {
 
     #[test]
     fn ensure_blanket_traits() {
-        ensure_type_implements_trait!(F, PrimeField);
+        // NB: this ensures `PrimeField` implementation too!
+        ensure_type_implements_trait!(F, FromPrimitiveWithConfig);
     }
 
     #[test]

src/field/crypto_bigint_monty.rs

@@ -544,7 +544,8 @@ mod tests {
 
     #[test]
     fn ensure_blanket_traits() {
-        ensure_type_implements_trait!(F, PrimeField);
+        // NB: this ensures `PrimeField` implementation too!
+        ensure_type_implements_trait!(F, FromPrimitiveWithConfig);
     }
 
     #[test]