use const-hex

Cargo.toml

@@ -668,6 +668,7 @@ codec = { version = "3.6.12", default-features = false, package = "parity-scale-
 collectives-westend-emulated-chain = { path = "cumulus/parachains/integration-tests/emulated/chains/parachains/collectives/collectives-westend" }
 collectives-westend-runtime = { path = "cumulus/parachains/runtimes/collectives/collectives-westend" }
 color-eyre = { version = "0.6.1", default-features = false }
+const-hex = { version = "1.10.0", default-features = false }
 color-print = { version = "0.3.4" }
 colored = { version = "2.0.4" }
 comfy-table = { version = "7.1.0", default-features = false }

substrate/frame/metadata-hash-extension/Cargo.toml

@@ -17,6 +17,7 @@ frame-support = { workspace = true }
 frame-system = { workspace = true }
 log = { workspace = true }
 docify = { workspace = true }
+const-hex = { workspace = true }
 
 [dev-dependencies]
 substrate-wasm-builder = { features = ["metadata-hash"], workspace = true, default-features = true }
@@ -36,4 +37,5 @@ std = [
 	"log/std",
 	"scale-info/std",
 	"sp-runtime/std",
+	"const-hex/std",
 ]

substrate/frame/metadata-hash-extension/src/lib.rs

@@ -50,7 +50,6 @@ use sp_runtime::{
 
 #[cfg(test)]
 mod tests;
-mod utils;
 
 /// The mode of [`CheckMetadataHash`].
 #[derive(Decode, Encode, PartialEq, Debug, TypeInfo, Clone, Copy, Eq)]
@@ -69,9 +68,13 @@ enum MetadataHash {
 	Custom([u8; 32]),
 }
 
-const RUNTIME_METADATA: Option<[u8; 32]> = match option_env!("RUNTIME_METADATA_HASH") {
-	Some(hex) => utils::hex_str_to_32_bytes(hex),
-	None => None,
+const RUNTIME_METADATA: Option<[u8; 32]> = if let Some(hex) = option_env!("RUNTIME_METADATA_HASH") {
+	match const_hex::const_decode_to_array(hex.as_bytes()) {
+		Ok(hex) => Some(hex),
+		Err(_) => None,
+	}
+} else {
+	None
 };
 
 impl MetadataHash {