Remove std feature, use core::error::Error, update docs

Signed-off-by: Denis Varlakov <[email protected]>

Cargo.toml

@@ -28,7 +28,6 @@ generic-ec = { version = "0.4", default-features = false, features = ["curve-sta
 
 [features]
 default = []
-std = []
 # Adds support of secp256k1 curve to slip10 derivation
 curve-secp256k1 = ["generic-ec/curve-secp256k1", "slip10"]
 # Adds support of secp256r1 curve to slip10 derivation
@@ -37,7 +36,7 @@ curve-secp256r1 = ["generic-ec/curve-secp256r1", "slip10"]
 curve-ed25519 = ["generic-ec/curve-ed25519", "edwards"]
 # Enables Stark-specific derivation
 curve-stark = ["generic-ec/curve-stark", "stark"]
-all-curves = ["curve-secp256k1", "curve-secp256r1", "curve-ed25519"]
+all-curves = ["curve-secp256k1", "curve-secp256r1", "curve-ed25519", "curve-stark"]
 serde = ["dep:serde", "generic-ec/serde"]
 
 # Enables Slip10 derivation

src/errors.rs

@@ -12,8 +12,7 @@ impl fmt::Display for InvalidLength {
     }
 }
 
-#[cfg(feature = "std")]
-impl std::error::Error for InvalidLength {}
+impl core::error::Error for InvalidLength {}
 
 /// Value was out of range
 #[derive(Debug)]
@@ -25,8 +24,7 @@ impl fmt::Display for OutOfRange {
     }
 }
 
-#[cfg(feature = "std")]
-impl std::error::Error for OutOfRange {}
+impl core::error::Error for OutOfRange {}
 
 /// Error returned by parsing child index
 #[derive(Debug)]
@@ -46,9 +44,8 @@ impl fmt::Display for ParseChildIndexError {
     }
 }
 
-#[cfg(feature = "std")]
-impl std::error::Error for ParseChildIndexError {
-    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+impl core::error::Error for ParseChildIndexError {
+    fn source(&self) -> Option<&(dyn core::error::Error + 'static)> {
         match self {
             ParseChildIndexError::ParseInt(e) => Some(e),
             ParseChildIndexError::IndexNotInRange(e) => Some(e),

src/lib.rs

@@ -54,18 +54,19 @@
 //! ```
 //!
 //! ### Features
-//! * `std`: enables std library support (mainly, it just implements [`Error`](std::error::Error)
-//!   trait for the error types)
-//! * `curve-secp256k1`, `curve-secp256r1`, `curve-ed25519` add curve implementation into the crate
-//!   [curves] module
+//! * `curve-secp256k1`, `curve-secp256r1`, `curve-ed25519`, `curve-stark` add curve implementation
+//!    into the crate [curves] module
+//! * `all-curves` adds all curves listed above
+//! * `slip10`, `edwards`, `stark` add [`slip10`], [`edwards`], and [`stark`] HD derivations respectively
+//! * `serde` adds `serde::{Serialize, Deserialize}` traits implementation to the types in the library
 //!
 //! ## Join us in Discord!
 //! Feel free to reach out to us [in Discord](https://discordapp.com/channels/905194001349627914/1285268686147424388)!
 //!
 //! [slip10-spec]: https://github.com/satoshilabs/slips/blob/master/slip-0010.md
 //! [bip32-spec]: https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki
 
-#![cfg_attr(not(feature = "std"), no_std)]
+#![no_std]
 #![forbid(missing_docs, unsafe_code)]
 #![cfg_attr(not(test), forbid(unused_crate_dependencies))]