elliptic-curve: fix weak feature activation TODOs

.github/workflows/elliptic-curve.yml

@@ -52,10 +52,9 @@ jobs:
       - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features sec1
       - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features serde
       - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features voprf
+      - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features alloc,arithmetic,pkcs8
       - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features alloc,serde
       - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features arithmetic,serde
-      - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features pkcs8,sec1
-      - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features pem,pkcs8,sec1
       - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features alloc,digest,ecdh,hazmat,hash2curve,jwk,pem,pkcs8,sec1,serde,voprf
 
   # TODO: use the reusable workflow after this crate is re-added to the

elliptic-curve/Cargo.toml

@@ -47,13 +47,15 @@ default = ["arithmetic"]
 alloc = ["base16ct/alloc", "der/alloc", "ff?/alloc", "group?/alloc", "sec1?/alloc", "zeroize/alloc"]
 std = ["alloc", "rand_core/std", "sec1?/std"]
 
-arithmetic = ["ff", "group"]
+arithmetic = ["group"]
 bits = ["arithmetic", "ff/bits"]
 dev = ["arithmetic", "hex-literal", "pem", "pkcs8"]
 hash2curve = ["arithmetic", "digest"]
 ecdh = ["arithmetic", "digest", "hkdf"]
+group = ["dep:group", "ff"]
 hazmat = []
 jwk = ["alloc", "base64ct/alloc", "serde", "serde_json", "zeroize/alloc"]
+pkcs8 = ["dep:pkcs8", "sec1"]
 pem = ["alloc", "arithmetic", "der/pem", "pem-rfc7468/alloc", "pkcs8", "sec1/pem"]
 serde = ["alloc", "pkcs8", "sec1/serde", "serdect"]
 voprf = ["digest"]

elliptic-curve/src/dev.rs

@@ -24,7 +24,7 @@ use hex_literal::hex;
 use pkcs8::AssociatedOid;
 
 #[cfg(feature = "bits")]
-use crate::group::ff::PrimeFieldBits;
+use ff::PrimeFieldBits;
 
 #[cfg(feature = "jwk")]
 use crate::JwkParameters;

elliptic-curve/src/scalar/core.rs

@@ -22,7 +22,7 @@ use zeroize::DefaultIsZeroes;
 #[cfg(feature = "arithmetic")]
 use {
     super::{Scalar, ScalarArithmetic},
-    group::ff::PrimeField,
+    ff::PrimeField,
 };
 
 #[cfg(feature = "serde")]

elliptic-curve/src/secret_key/pkcs8.rs

@@ -10,8 +10,7 @@ use der::Decode;
 use sec1::EcPrivateKey;
 
 // Imports for the `EncodePrivateKey` impl
-// TODO(tarcieri): use weak activation of `pkcs8/alloc` for gating `EncodePrivateKey` impl
-#[cfg(all(feature = "arithmetic", feature = "pem"))]
+#[cfg(all(feature = "alloc", feature = "arithmetic"))]
 use {
     crate::{
         sec1::{FromEncodedPoint, ToEncodedPoint},
@@ -51,10 +50,7 @@ where
 {
 }
 
-// TODO(tarcieri): use weak activation of `pkcs8/alloc` for this when possible
-// It doesn't strictly depend on `pkcs8/pem` but we can't easily activate `pkcs8/alloc`
-// without adding a separate crate feature just for this functionality.
-#[cfg(all(feature = "arithmetic", feature = "pem"))]
+#[cfg(all(feature = "alloc", feature = "arithmetic"))]
 impl<C> EncodePrivateKey for SecretKey<C>
 where
     C: Curve + AssociatedOid + ProjectiveArithmetic,