Merge pull request #6 from dfns-labs/no-std

Allow `no_std` for `generic-ec-zkp`

.github/workflows/rust.yml

@@ -19,7 +19,9 @@ jobs:
         cache-on-failure: "true"
     - name: Build no-std
       run: cargo build -p generic-ec --no-default-features
-    - name: Build
+    - name: Build with `alloc` only
+      run: cargo build -p generic-ec --no-default-features --features alloc
+    - name: Build all-features
       run: cargo build -p generic-ec --all-features
     - name: Run tests
       run: cargo test

generic-ec-zkp/Cargo.toml

@@ -27,4 +27,7 @@ generic-tests = "0.1"
 generic-ec = { path = "../generic-ec", default-features = false, features = ["all-curves"] }
 
 [features]
+default = ["std"]
+std = ["alloc"]
+alloc = []
 serde = ["dep:serde", "generic-ec/serde", "generic-array/serde"]

generic-ec-zkp/src/hash_commitment.rs

@@ -275,4 +275,14 @@ impl EncodesToBytes for u16 {
 }
 
 /// Error indicating that revealed data doesn't match commitment
+#[derive(Debug, Clone, Copy)]
 pub struct MismatchedRevealedData;
+
+impl core::fmt::Display for MismatchedRevealedData {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        f.write_str("revealed data doesn't match commitment")
+    }
+}
+
+#[cfg(feature = "std")]
+impl std::error::Error for MismatchedRevealedData {}

generic-ec-zkp/src/lib.rs

@@ -1,5 +1,10 @@
 #![cfg_attr(not(test), forbid(unused_crate_dependencies))]
 #![cfg_attr(not(test), deny(clippy::unwrap_used, clippy::expect_used))]
+#![cfg_attr(docsrs, feature(doc_cfg))]
+#![cfg_attr(not(feature = "std"), no_std)]
+
+#[cfg(feature = "alloc")]
+extern crate alloc;
 
 // We don't want this dependency to trigger unused dep lint
 use generic_array as _;