chore: feature-gate getrandom, document in README.md (#71)

* docs: document wasm32-unknown-unknown getrandom failures

* chore: feature-gate `getrandom`

Cargo.toml

@@ -48,6 +48,7 @@ thiserror = "1.0"
 arbitrary = { version = "1.3", default-features = false }
 arrayvec = { version = "0.7.2", default-features = false }
 bytes = { version = "1.4", default-features = false }
+getrandom = "0.2"
 hex = { package = "const-hex", version = ">=1.5", default-features = false, features = ["alloc"] }
 once_cell = "1.17"
 proptest = "1.1"

README.md

@@ -59,17 +59,29 @@ Alloy project.
 Pull requests will not be merged unless CI passes, so please ensure that your
 contribution follows the linting rules and passes clippy.
 
-## Note on WASM
+## WASM support
 
-We provide full support for all the `wasm*-*` targets. If any crate does not
+We provide full support for all the `wasm*-*` targets. If a crate does not
 build on a WASM target, please [open an issue].
 
+When building for the `wasm32-unknown-unknown` target and the `"getrandom"`
+feature is enabled, compilation for the `getrandom`  crate will fail. This is
+expected: see [their documentation][getrandom] for more details.
+
+To fix this, either disable the `"getrandom"` feature on `alloy-core` or add
+`getrandom` to your dependencies with the `"js"` feature enabled:
+
+```toml
+getrandom = { version = "0.2", features = ["js"] }
+```
+
 There is currently no plan to provide an official JS/TS-accessible library
 interface, as we believe [viem] or [ethers.js] serve that need very well.
 
+[open an issue]: https://github.com/alloy-rs/core/issues/new
+[getrandom]: https://docs.rs/getrandom/#webassembly-support
 [viem]: https://viem.sh
 [ethers.js]: https://docs.ethers.io/v6/
-[open an issue]: https://github.com/alloy-rs/core/issues/new
 
 ## Note on `no_std`
 

crates/primitives/Cargo.toml

@@ -23,7 +23,6 @@ ruint = { workspace = true, features = ["serde"] }
 
 # utility
 bytes.workspace = true
-getrandom = "0.2"
 hex.workspace = true
 itoa = "1"
 tiny-keccak = { workspace = true, features = ["keccak"] }
@@ -37,6 +36,9 @@ alloy-rlp = { workspace = true, optional = true }
 # serde
 serde = { workspace = true, optional = true }
 
+# getrandom
+getrandom = { workspace = true, optional = true }
+
 # arbitrary
 arbitrary = { workspace = true, features = ["derive"], optional = true }
 proptest = { workspace = true, optional = true }
@@ -49,6 +51,7 @@ serde_json.workspace = true
 [features]
 default = ["std", "rlp", "serde"]
 std = ["bytes/std", "hex/std", "alloy-rlp?/std", "proptest?/std", "serde/std"]
+getrandom = ["dep:getrandom"]
 rlp = ["dep:alloy-rlp", "ruint/fastrlp"]
 serde = ["dep:serde", "bytes/serde", "hex/serde", "ruint/serde"]
 arbitrary = [

crates/primitives/src/bits/fixed.rs

@@ -133,12 +133,14 @@ impl<const N: usize> FixedBytes<N> {
     }
 
     /// Instantiates a new fixed hash with cryptographically random content.
+    #[cfg(feature = "getrandom")]
     #[inline]
     pub fn random() -> Self {
         Self::try_random().unwrap()
     }
 
     /// Instantiates a new fixed hash with cryptographically random content.
+    #[cfg(feature = "getrandom")]
     pub fn try_random() -> Result<Self, getrandom::Error> {
         let mut bytes: [_; N] = super::impl_core::uninit_array();
         getrandom::getrandom_uninit(&mut bytes)?;

crates/primitives/src/bits/macros.rs

@@ -119,18 +119,6 @@ macro_rules! wrap_fixed_bytes {
                 Self($crate::FixedBytes::with_last_byte(x))
             }
 
-            /// Instantiates a new fixed hash with cryptographically random content.
-            #[inline]
-            pub fn random() -> Self {
-                Self($crate::FixedBytes::random())
-            }
-
-            /// Instantiates a new fixed hash with cryptographically random content.
-            #[inline]
-            pub fn try_random() -> ::core::result::Result<Self, $crate::private::getrandom::Error> {
-                $crate::FixedBytes::try_random().map(Self)
-            }
-
             /// Returns a new fixed hash where all bits are set to the given byte.
             #[inline]
             pub const fn repeat_byte(byte: u8) -> Self {
@@ -166,16 +154,19 @@ macro_rules! wrap_fixed_bytes {
             pub fn as_fixed_bytes_mut(&mut self) -> &mut [u8; $n] {
                 self.0.as_fixed_bytes_mut()
             }
+
             /// Returns the inner bytes array.
             #[inline]
             pub const fn to_fixed_bytes(self) -> [u8; $n] {
                 self.0.to_fixed_bytes()
             }
+
             /// Returns a constant raw pointer to the value.
             #[inline]
             pub const fn as_ptr(&self) -> *const u8 {
                 self.as_bytes().as_ptr()
             }
+
             /// Returns a mutable raw pointer to the value.
             #[inline]
             pub fn as_mut_ptr(&mut self) -> *mut u8 {
@@ -247,12 +238,41 @@ macro_rules! wrap_fixed_bytes {
             }
         }
 
+        $crate::impl_getrandom!($name);
         $crate::impl_rlp!($name);
         $crate::impl_serde!($name);
         $crate::impl_arbitrary!($name, $n);
     };
 }
 
+#[doc(hidden)]
+#[macro_export]
+#[cfg(feature = "getrandom")]
+macro_rules! impl_getrandom {
+    ($t:ty) => {
+        impl $t {
+            /// Instantiates a new fixed hash with cryptographically random content.
+            #[inline]
+            pub fn random() -> Self {
+                Self($crate::FixedBytes::random())
+            }
+
+            /// Instantiates a new fixed hash with cryptographically random content.
+            #[inline]
+            pub fn try_random() -> ::core::result::Result<Self, $crate::private::getrandom::Error> {
+                $crate::FixedBytes::try_random().map(Self)
+            }
+        }
+    };
+}
+
+#[doc(hidden)]
+#[macro_export]
+#[cfg(not(feature = "getrandom"))]
+macro_rules! impl_getrandom {
+    ($t:ty) => {};
+}
+
 #[doc(hidden)]
 #[macro_export]
 #[cfg(feature = "rlp")]

crates/primitives/src/lib.rs

@@ -43,6 +43,8 @@ pub use ruint::{self, uint, Uint};
 #[doc(hidden)]
 pub mod private {
     pub use derive_more;
+
+    #[cfg(feature = "getrandom")]
     pub use getrandom;
 
     #[cfg(feature = "rlp")]