Added cfg_attr everywhere possible, and simplified cfg over std/alloc

Makefile

@@ -1,4 +1,4 @@
-FEATURES := nightly simd_backend packed_simd
+FEATURES := simd_backend serde
 
 doc:
 	cargo +nightly rustdoc --features "$(FEATURES)" -- --html-in-header docs/assets/rustdoc-include-katex-header.html --cfg docsrs

src/backend/mod.rs

@@ -37,4 +37,5 @@
 pub mod serial;
 
 #[cfg(any(feature = "simd_backend", docsrs))]
+#[cfg_attr(docsrs, doc(cfg(feature = "simd_backend")))]
 pub mod vector;

src/backend/serial/mod.rs

@@ -23,15 +23,25 @@ use cfg_if::cfg_if;
 cfg_if! {
     if #[cfg(feature = "fiat_backend")] {
         #[cfg(not(target_pointer_width = "64"))]
+        #[cfg_attr(
+            docsrs,
+            doc(cfg(all(feature = "fiat_backend", not(target_pointer_width = "64"))))
+        )]
         pub mod fiat_u32;
 
         #[cfg(target_pointer_width = "64")]
+        #[cfg_attr(
+            docsrs,
+            doc(cfg(all(feature = "fiat_backend", target_pointer_width = "64")))
+        )]
         pub mod fiat_u64;
     } else {
         #[cfg(not(target_pointer_width = "64"))]
+        #[cfg_attr(docsrs, doc(cfg(not(target_pointer_width = "64"))))]
         pub mod u32;
 
         #[cfg(target_pointer_width = "64")]
+        #[cfg_attr(docsrs, doc(cfg(target_pointer_width = "64")))]
         pub mod u64;
     }
 }
@@ -42,4 +52,11 @@ pub mod curve_models;
     feature = "simd_backend",
     any(target_feature = "avx2", target_feature = "avx512ifma")
 )))]
+#[cfg_attr(
+    docsrs,
+    doc(cfg(not(all(
+        feature = "simd_backend",
+        any(target_feature = "avx2", target_feature = "avx512ifma")
+    ))))
+)]
 pub mod scalar_mul;

src/backend/serial/scalar_mul/pippenger.rs

@@ -61,7 +61,8 @@ use crate::prelude::*;
 /// This algorithm is adapted from section 4 of <https://eprint.iacr.org/2012/549.pdf>.
 pub struct Pippenger;
 
-#[cfg(any(feature = "alloc", feature = "std"))]
+#[cfg(feature = "alloc")]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "alloc", feature = "std"))))]
 impl VartimeMultiscalarMul for Pippenger {
     type Point = EdwardsPoint;
 

src/backend/vector/mod.rs

@@ -18,22 +18,36 @@ compile_error!("simd_backend selected without target_feature=+avx2 or +avx512ifm
     all(target_feature = "avx2", not(target_feature = "avx512ifma")),
     docsrs
 ))]
+#[cfg_attr(
+    docsrs,
+    doc(cfg(all(target_feature = "avx2", not(target_feature = "avx512ifma")),))
+)]
 pub mod avx2;
 #[cfg(any(
     all(target_feature = "avx2", not(target_feature = "avx512ifma")),
     docsrs
 ))]
+#[cfg_attr(
+    docsrs,
+    doc(cfg(all(target_feature = "avx2", not(target_feature = "avx512ifma")),))
+)]
 pub(crate) use self::avx2::{
     constants::BASEPOINT_ODD_LOOKUP_TABLE, edwards::CachedPoint, edwards::ExtendedPoint,
 };
 
 #[cfg(any(target_feature = "avx512ifma", docsrs))]
+#[cfg_attr(docsrs, doc(cfg(target_feature = "avx512ifma")))]
 pub mod ifma;
 #[cfg(target_feature = "avx512ifma")]
+#[cfg_attr(docsrs, doc(cfg(target_feature = "avx512ifma")))]
 pub(crate) use self::ifma::{
     constants::BASEPOINT_ODD_LOOKUP_TABLE, edwards::CachedPoint, edwards::ExtendedPoint,
 };
 
 #[cfg(any(target_feature = "avx2", target_feature = "avx512ifma", docsrs))]
+#[cfg_attr(
+    docsrs,
+    doc(cfg(any(target_feature = "avx2", target_feature = "avx512ifma")))
+)]
 #[allow(missing_docs)]
 pub mod scalar_mul;

src/backend/vector/scalar_mul/mod.rs

@@ -14,10 +14,13 @@ pub mod variable_base;
 pub mod vartime_double_base;
 
 #[cfg(feature = "alloc")]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "alloc", feature = "std"))))]
 pub mod straus;
 
 #[cfg(feature = "alloc")]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "alloc", feature = "std"))))]
 pub mod precomputed_straus;
 
 #[cfg(feature = "alloc")]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "alloc", feature = "std"))))]
 pub mod pippenger;

src/backend/vector/scalar_mul/pippenger.rs

@@ -24,7 +24,8 @@ use crate::prelude::*;
 /// See the documentation in the serial `scalar_mul::pippenger` module for details.
 pub struct Pippenger;
 
-#[cfg(any(feature = "alloc", feature = "std"))]
+#[cfg(feature = "alloc")]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "alloc", feature = "std"))))]
 impl VartimeMultiscalarMul for Pippenger {
     type Point = EdwardsPoint;
 

src/edwards.rs

@@ -134,9 +134,9 @@ use crate::traits::BasepointTable;
 use crate::traits::ValidityCheck;
 use crate::traits::{Identity, IsIdentity};
 
-#[cfg(any(feature = "alloc", feature = "std"))]
+#[cfg(feature = "alloc")]
 use crate::traits::MultiscalarMul;
-#[cfg(any(feature = "alloc", feature = "std"))]
+#[cfg(feature = "alloc")]
 use crate::traits::{VartimeMultiscalarMul, VartimePrecomputedMultiscalarMul};
 
 #[cfg(not(all(
@@ -223,6 +223,7 @@ use serde::de::Visitor;
 use serde::{self, Deserialize, Deserializer, Serialize, Serializer};
 
 #[cfg(feature = "serde")]
+#[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
 impl Serialize for EdwardsPoint {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
@@ -238,6 +239,7 @@ impl Serialize for EdwardsPoint {
 }
 
 #[cfg(feature = "serde")]
+#[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
 impl Serialize for CompressedEdwardsY {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
@@ -253,6 +255,7 @@ impl Serialize for CompressedEdwardsY {
 }
 
 #[cfg(feature = "serde")]
+#[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
 impl<'de> Deserialize<'de> for EdwardsPoint {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -288,6 +291,7 @@ impl<'de> Deserialize<'de> for EdwardsPoint {
 }
 
 #[cfg(feature = "serde")]
+#[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
 impl<'de> Deserialize<'de> for CompressedEdwardsY {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -707,6 +711,7 @@ impl<'a, 'b> Mul<&'b EdwardsPoint> for &'a Scalar {
 // forward to a specific backend implementation.
 
 #[cfg(feature = "alloc")]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "alloc", feature = "std"))))]
 impl MultiscalarMul for EdwardsPoint {
     type Point = EdwardsPoint;
 
@@ -739,6 +744,7 @@ impl MultiscalarMul for EdwardsPoint {
 }
 
 #[cfg(feature = "alloc")]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "alloc", feature = "std"))))]
 impl VartimeMultiscalarMul for EdwardsPoint {
     type Point = EdwardsPoint;
 
@@ -778,9 +784,11 @@ impl VartimeMultiscalarMul for EdwardsPoint {
 // decouple stability of the inner type from the stability of the
 // outer type.
 #[cfg(feature = "alloc")]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "alloc", feature = "std"))))]
 pub struct VartimeEdwardsPrecomputation(scalar_mul::precomputed_straus::VartimePrecomputedStraus);
 
 #[cfg(feature = "alloc")]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "alloc", feature = "std"))))]
 impl VartimePrecomputedMultiscalarMul for VartimeEdwardsPrecomputation {
     type Point = EdwardsPoint;
 

src/field.rs

@@ -38,8 +38,16 @@ use crate::constants;
 cfg_if! {
     if #[cfg(feature = "fiat_backend")] {
         #[cfg(not(target_pointer_width = "64"))]
+        #[cfg_attr(
+            docsrs,
+            doc(cfg(all(feature = "fiat_backend", not(target_pointer_width = "64"))))
+        )]
         pub use backend::serial::fiat_u32::field::*;
         #[cfg(target_pointer_width = "64")]
+        #[cfg_attr(
+            docsrs,
+            doc(cfg(all(feature = "fiat_backend", target_pointer_width = "64")))
+        )]
         pub use backend::serial::fiat_u64::field::*;
 
         /// A `FieldElement` represents an element of the field
@@ -50,6 +58,10 @@ cfg_if! {
         ///
         /// Using formally-verified field arithmetic from fiat-crypto.
         #[cfg(not(target_pointer_width = "64"))]
+        #[cfg_attr(
+            docsrs,
+            doc(cfg(all(feature = "fiat_backend", not(target_pointer_width = "64"))))
+        )]
         pub type FieldElement = backend::serial::fiat_u32::field::FieldElement2625;
 
         /// A `FieldElement` represents an element of the field
@@ -60,8 +72,13 @@ cfg_if! {
         ///
         /// Using formally-verified field arithmetic from fiat-crypto.
         #[cfg(target_pointer_width = "64")]
+        #[cfg_attr(
+            docsrs,
+            doc(cfg(all(feature = "fiat_backend", target_pointer_width = "64")))
+        )]
         pub type FieldElement = backend::serial::fiat_u64::field::FieldElement51;
     } else if #[cfg(target_pointer_width = "64")] {
+        #[cfg_attr(docsrs, doc(cfg(target_pointer_width = "64")))]
         pub use crate::backend::serial::u64::field::*;
 
         /// A `FieldElement` represents an element of the field
@@ -69,8 +86,10 @@ cfg_if! {
         ///
         /// The `FieldElement` type is an alias for one of the platform-specific
         /// implementations.
+        #[cfg_attr(docsrs, doc(cfg(target_pointer_width = "64")))]
         pub type FieldElement = backend::serial::u64::field::FieldElement51;
     } else {
+        #[cfg_attr(docsrs, doc(cfg(not(target_pointer_width = "64"))))]
         pub use backend::serial::u32::field::*;
 
         /// A `FieldElement` represents an element of the field
@@ -78,6 +97,7 @@ cfg_if! {
         ///
         /// The `FieldElement` type is an alias for one of the platform-specific
         /// implementations.
+        #[cfg_attr(docsrs, doc(cfg(not(target_pointer_width = "64"))))]
         pub type FieldElement = backend::serial::u32::field::FieldElement2625;
     }
 }
@@ -167,6 +187,7 @@ impl FieldElement {
     ///
     /// When an input `FieldElement` is zero, its value is unchanged.
     #[cfg(feature = "alloc")]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "alloc", feature = "std"))))]
     pub fn batch_invert(inputs: &mut [FieldElement]) {
         // Montgomery’s Trick and Fast Implementation of Masked AES
         // Genelle, Prouff and Quisquater

src/ristretto.rs

@@ -190,7 +190,7 @@ use crate::scalar::Scalar;
 
 use crate::traits::BasepointTable;
 use crate::traits::Identity;
-#[cfg(any(feature = "alloc", feature = "std"))]
+#[cfg(feature = "alloc")]
 use crate::traits::{MultiscalarMul, VartimeMultiscalarMul, VartimePrecomputedMultiscalarMul};
 
 #[cfg(not(all(
@@ -341,6 +341,7 @@ use serde::de::Visitor;
 use serde::{self, Deserialize, Deserializer, Serialize, Serializer};
 
 #[cfg(feature = "serde")]
+#[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
 impl Serialize for RistrettoPoint {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
@@ -356,6 +357,7 @@ impl Serialize for RistrettoPoint {
 }
 
 #[cfg(feature = "serde")]
+#[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
 impl Serialize for CompressedRistretto {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
@@ -371,6 +373,7 @@ impl Serialize for CompressedRistretto {
 }
 
 #[cfg(feature = "serde")]
+#[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
 impl<'de> Deserialize<'de> for RistrettoPoint {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -406,6 +409,7 @@ impl<'de> Deserialize<'de> for RistrettoPoint {
 }
 
 #[cfg(feature = "serde")]
+#[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
 impl<'de> Deserialize<'de> for CompressedRistretto {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -520,6 +524,7 @@ impl RistrettoPoint {
     /// # }
     /// ```
     #[cfg(feature = "alloc")]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "alloc", feature = "std"))))]
     pub fn double_and_compress_batch<'a, I>(points: I) -> Vec<CompressedRistretto>
     where
         I: IntoIterator<Item = &'a RistrettoPoint>,
@@ -922,6 +927,7 @@ define_mul_variants!(LHS = Scalar, RHS = RistrettoPoint, Output = RistrettoPoint
 // forward to the EdwardsPoint implementations.
 
 #[cfg(feature = "alloc")]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "alloc", feature = "std"))))]
 impl MultiscalarMul for RistrettoPoint {
     type Point = RistrettoPoint;
 
@@ -938,6 +944,7 @@ impl MultiscalarMul for RistrettoPoint {
 }
 
 #[cfg(feature = "alloc")]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "alloc", feature = "std"))))]
 impl VartimeMultiscalarMul for RistrettoPoint {
     type Point = RistrettoPoint;
 
@@ -958,9 +965,11 @@ impl VartimeMultiscalarMul for RistrettoPoint {
 // decouple stability of the inner type from the stability of the
 // outer type.
 #[cfg(feature = "alloc")]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "alloc", feature = "std"))))]
 pub struct VartimeRistrettoPrecomputation(scalar_mul::precomputed_straus::VartimePrecomputedStraus);
 
 #[cfg(feature = "alloc")]
+#[cfg_attr(docsrs, doc(cfg(any(feature = "alloc", feature = "std"))))]
 impl VartimePrecomputedMultiscalarMul for VartimeRistrettoPrecomputation {
     type Point = RistrettoPoint;
 

src/scalar.rs

@@ -173,6 +173,10 @@ cfg_if! {
         /// This is a type alias for one of the scalar types in the `backend`
         /// module.
         #[cfg(not(target_pointer_width = "64"))]
+        #[cfg_attr(
+            docsrs,
+            doc(cfg(all(feature = "fiat_backend", not(target_pointer_width = "64"))))
+        )]
         type UnpackedScalar = backend::serial::fiat_u32::scalar::Scalar29;
 
         /// An `UnpackedScalar` represents an element of the field GF(l), optimized for speed.
@@ -180,18 +184,24 @@ cfg_if! {
         /// This is a type alias for one of the scalar types in the `backend`
         /// module.
         #[cfg(target_pointer_width = "64")]
+        #[cfg_attr(
+            docsrs,
+            doc(cfg(all(feature = "fiat_backend", target_pointer_width = "64")))
+        )]
         type UnpackedScalar = backend::serial::fiat_u64::scalar::Scalar52;
     } else if #[cfg(target_pointer_width = "64")] {
         /// An `UnpackedScalar` represents an element of the field GF(l), optimized for speed.
         ///
         /// This is a type alias for one of the scalar types in the `backend`
         /// module.
+        #[cfg_attr(docsrs, doc(cfg(target_pointer_width = "64")))]
         type UnpackedScalar = backend::serial::u64::scalar::Scalar52;
     } else {
         /// An `UnpackedScalar` represents an element of the field GF(l), optimized for speed.
         ///
         /// This is a type alias for one of the scalar types in the `backend`
         /// module.
+        #[cfg_attr(docsrs, doc(cfg(not(target_pointer_width = "64"))))]
         type UnpackedScalar = backend::serial::u32::scalar::Scalar29;
     }
 }
@@ -401,6 +411,7 @@ use serde::de::Visitor;
 use serde::{self, Deserialize, Deserializer, Serialize, Serializer};
 
 #[cfg(feature = "serde")]
+#[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
 impl Serialize for Scalar {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
@@ -416,6 +427,7 @@ impl Serialize for Scalar {
 }
 
 #[cfg(feature = "serde")]
+#[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
 impl<'de> Deserialize<'de> for Scalar {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -773,6 +785,7 @@ impl Scalar {
     /// # }
     /// ```
     #[cfg(feature = "alloc")]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "alloc", feature = "std"))))]
     pub fn batch_invert(inputs: &mut [Scalar]) -> Scalar {
         // This code is essentially identical to the FieldElement
         // implementation, and is documented there.  Unfortunately,