Merge branch 'solana/mcm-clear-root' into solana/mcm-configset-event

chains/solana/contracts/programs/mcm/src/instructions/set_config.rs

@@ -135,6 +135,27 @@ pub fn set_config(
         root_metadata.override_previous_root = true;
     }
 
+    // clear_root is equivalent to overriding with a completely empty root
+    if clear_root {
+        let expiring_root = &mut ctx.accounts.expiring_root_and_op_count;
+        let root_metadata = &mut ctx.accounts.root_metadata;
+
+        // preserve the current op_count
+        let current_op_count = expiring_root.op_count;
+
+        // clear the expiring root while preserving op_count
+        expiring_root.root = [0u8; 32]; // clear root (equivalent to bytes32(0) in Solidity)
+        expiring_root.valid_until = 0; // clear timestamp
+        expiring_root.op_count = current_op_count;
+
+        // set root metadata to a cleared state
+        root_metadata.chain_id = ctx.accounts.multisig_config.chain_id;
+        root_metadata.multisig = ctx.accounts.multisig_config.key();
+        root_metadata.pre_op_count = current_op_count;
+        root_metadata.post_op_count = current_op_count;
+        root_metadata.override_previous_root = true;
+    }
+
     emit!(ConfigSet {
         group_parents,
         group_quorums,