stop using unstable remove_try_from_fn_array

Author: ohad-agadi

crates/stwo/src/core/proof.rs

@@ -1,5 +1,5 @@
+use core::mem;
 use core::ops::Deref;
-use core::{array, mem};
 
 use serde::{Deserialize, Serialize};
 use std_shims::Vec;
@@ -12,37 +12,29 @@ use crate::core::vcs::hash::Hash;
 use crate::core::vcs::verifier::MerkleDecommitment;
 use crate::core::vcs::MerkleHasher;
 
-/// Error when the sampled values have an invalid structure.
-#[derive(Clone, Copy, Debug)]
-pub struct InvalidOodsSampleStructure;
-
 #[derive(Clone, Debug, Serialize, Deserialize)]
 pub struct StarkProof<H: MerkleHasher>(pub CommitmentSchemeProof<H>);
 
 impl<H: MerkleHasher> StarkProof<H> {
     /// Extracts the composition trace Out-Of-Domain-Sample evaluation from the mask.
-    pub(crate) fn extract_composition_oods_eval(
-        &self,
-    ) -> Result<SecureField, InvalidOodsSampleStructure> {
-        // TODO(andrew): `[.., composition_mask, _quotients_mask]` when add quotients commitment.
+    pub(crate) fn extract_composition_oods_eval(&self) -> Option<SecureField> {
+        // TODO(andrew): `[.., composition_mask, _quotients_mask]` when add quotients
+        // commitment.
         let [.., composition_mask] = &**self.sampled_values else {
-            return Err(InvalidOodsSampleStructure);
+            return None;
         };
-
-        let mut composition_cols = composition_mask.iter();
-
-        let coordinate_evals = array::try_from_fn(|_| {
-            let col = &**composition_cols.next().ok_or(InvalidOodsSampleStructure)?;
-            let [eval] = col.try_into().map_err(|_| InvalidOodsSampleStructure)?;
-            Ok(eval)
-        })?;
-
-        // Too many columns.
-        if composition_cols.next().is_some() {
-            return Err(InvalidOodsSampleStructure);
-        }
-
-        Ok(SecureField::from_partial_evals(coordinate_evals))
+        let coordinate_evals = composition_mask
+            .iter()
+            .map(|columns| {
+                let &[eval] = &columns[..] else {
+                    return None;
+                };
+                Some(eval)
+            })
+            .collect::<Option<Vec<_>>>()?
+            .try_into()
+            .ok()?;
+        Some(SecureField::from_partial_evals(coordinate_evals))
     }
 
     /// Returns the estimate size (in bytes) of the proof.

crates/stwo/src/core/verifier.rs

@@ -53,11 +53,12 @@ pub fn verify<MC: MerkleChannel>(
         sample_points_by_column.into_iter().flatten().count()
     );
 
-    let composition_oods_eval = proof.extract_composition_oods_eval().map_err(|_| {
-        VerificationError::InvalidStructure(std_shims::ToString::to_string(
-            &"Unexpected sampled_values structure",
-        ))
-    })?;
+    let composition_oods_eval =
+        proof
+            .extract_composition_oods_eval()
+            .ok_or(VerificationError::InvalidStructure(
+                std_shims::ToString::to_string(&"Unexpected sampled_values structure"),
+            ))?;
 
     if composition_oods_eval
         != components.eval_composition_polynomial_at_point(

crates/stwo/src/lib.rs

@@ -4,7 +4,6 @@
     feature(stdarch_x86_avx512)
 )]
 #![cfg_attr(not(feature = "std"), no_std)]
-#![feature(array_try_from_fn)]
 #![cfg_attr(
     feature = "prover",
     feature(array_chunks, iter_array_chunks, portable_simd, slice_ptr_get)