From a2748bbf292095135a588965629e8b602c95c118 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Grzegorz=20=C5=9Awirski?= <grzegorz@swirski.name>
Date: Wed, 16 Apr 2025 11:27:12 +0200
Subject: [PATCH] remove unsafe FromIterator<(NonZero<u8>, Option<RpoDigest>)>

---
 miden-crypto/src/merkle/sparse_path.rs | 43 ++++++++------------------
 1 file changed, 13 insertions(+), 30 deletions(-)

diff --git a/miden-crypto/src/merkle/sparse_path.rs b/miden-crypto/src/merkle/sparse_path.rs
index 305221c..8095452 100644
--- a/miden-crypto/src/merkle/sparse_path.rs
+++ b/miden-crypto/src/merkle/sparse_path.rs
@@ -147,17 +147,21 @@ impl SparseMerklePath {
             return Err(MerkleError::DepthTooBig(tree_depth as u64));
         }
 
-        let path: Self = iter::zip(path_depth_iter(tree_depth), iter)
-            .map(|(depth, node)| {
-                let &equivalent_empty_node = EmptySubtreeRoots::entry(tree_depth, depth.get());
-                let is_empty = node == equivalent_empty_node;
-                let node = if is_empty { None } else { Some(node) };
+        let mut empty_nodes_mask: u64 = 0;
+        let mut nodes: Vec<RpoDigest> = Default::default();
 
-                (depth, node)
-            })
-            .collect();
+        for (depth, node) in iter::zip(path_depth_iter(tree_depth), iter) {
+            let &equivalent_empty_node = EmptySubtreeRoots::entry(tree_depth, depth.get());
+            let is_empty = node == equivalent_empty_node;
+            let node = if is_empty { None } else { Some(node) };
 
-        Ok(path)
+            match node {
+                Some(node) => nodes.push(node),
+                None => empty_nodes_mask |= Self::bitmask_for_depth(depth),
+            }
+        }
+
+        Ok(SparseMerklePath { nodes, empty_nodes_mask })
     }
 
     const fn bitmask_for_depth(node_depth: NonZero<u8>) -> u64 {
@@ -246,27 +250,6 @@ impl From<SparseMerklePath> for Vec<RpoDigest> {
 // ITERATORS
 // ================================================================================================
 
-/// Contructs a [SparseMerklePath] out of an iterator of optional nodes, where `None` indicates an
-/// empty node.
-impl FromIterator<(NonZero<u8>, Option<RpoDigest>)> for SparseMerklePath {
-    fn from_iter<I>(iter: I) -> SparseMerklePath
-    where
-        I: IntoIterator<Item = (NonZero<u8>, Option<RpoDigest>)>,
-    {
-        let mut empty_nodes_mask: u64 = 0;
-        let mut nodes: Vec<RpoDigest> = Default::default();
-
-        for (depth, node) in iter {
-            match node {
-                Some(node) => nodes.push(node),
-                None => empty_nodes_mask |= Self::bitmask_for_depth(depth),
-            }
-        }
-
-        SparseMerklePath { nodes, empty_nodes_mask }
-    }
-}
-
 impl<'p> IntoIterator for &'p SparseMerklePath {
     type Item = <SparseMerklePathIter<'p> as Iterator>::Item;
     type IntoIter = SparseMerklePathIter<'p>;