chore(bb): make compile on stock mac clang (#8278)

xcode clang does not support all of c++20 it seems e.g. can't do
Constructor(A,B,C) where A B and C are the members of a struct with only
default constructors. Some common issues that come up like the
uint64_t/size_t split

barretenberg/cpp/src/barretenberg/aztec_ivc/aztec_ivc.cpp

@@ -14,7 +14,7 @@ void AztecIVC::complete_kernel_circuit_logic(ClientCircuit& circuit)
 {
     circuit.databus_propagation_data.is_kernel = true;
 
-    // Peform recursive verification and databus consistency checks for each entry in the verification queue
+    // Perform recursive verification and databus consistency checks for each entry in the verification queue
     for (auto& [proof, vkey, type] : verification_queue) {
         // Construct stdlib verification key and proof
         auto stdlib_proof = bb::convert_proof_to_witness(&circuit, proof);

barretenberg/cpp/src/barretenberg/commitment_schemes/ipa/ipa.test.cpp

@@ -300,9 +300,9 @@ TEST_F(IPATest, GeminiShplonkIPAWithShift)
         std::string label = "Gemini:a_" + std::to_string(l);
         const auto& evaluation = gemini_opening_pairs[l + 1].evaluation;
         prover_transcript->send_to_verifier(label, evaluation);
-        opening_claims.emplace_back(gemini_witnesses[l], gemini_opening_pairs[l]);
+        opening_claims.push_back({ gemini_witnesses[l], gemini_opening_pairs[l] });
     }
-    opening_claims.emplace_back(gemini_witnesses[log_n], gemini_opening_pairs[log_n]);
+    opening_claims.push_back({ gemini_witnesses[log_n], gemini_opening_pairs[log_n] });
 
     const auto opening_claim = ShplonkProver::prove(this->ck(), opening_claims, prover_transcript);
     IPA::compute_opening_proof(this->ck(), opening_claim, prover_transcript);

barretenberg/cpp/src/barretenberg/commitment_schemes/kzg/kzg.test.cpp

@@ -134,9 +134,9 @@ TYPED_TEST(KZGTest, GeminiShplonkKzgWithShift)
         std::string label = "Gemini:a_" + std::to_string(l);
         const auto& evaluation = gemini_opening_pairs[l + 1].evaluation;
         prover_transcript->send_to_verifier(label, evaluation);
-        opening_claims.emplace_back(gemini_witnesses[l], gemini_opening_pairs[l]);
+        opening_claims.push_back({ gemini_witnesses[l], gemini_opening_pairs[l] });
     }
-    opening_claims.emplace_back(gemini_witnesses[log_n], gemini_opening_pairs[log_n]);
+    opening_claims.push_back({ gemini_witnesses[log_n], gemini_opening_pairs[log_n] });
 
     // Shplonk prover output:
     // - opening pair: (z_challenge, 0)

barretenberg/cpp/src/barretenberg/crypto/merkle_tree/indexed_tree/indexed_tree.hpp

@@ -446,7 +446,7 @@ void IndexedTree<Store, HashingPolicy>::perform_insertions(size_t total_leaves,
 
     // We now kick off multiple workers to perform the low leaf updates
     // We create set of signals to coordinate the workers as the move up the tree
-    std::shared_ptr<std::vector<Signal>> signals = std::make_shared<std::vector<Signal>>();
+    auto signals = std::make_shared<std::vector<Signal>>();
     std::shared_ptr<Status> status = std::make_shared<Status>();
     // The first signal is set to 0. This ensures the first worker up the tree is not impeded
     signals->emplace_back(0);

barretenberg/cpp/src/barretenberg/crypto/merkle_tree/lmdb_store/lmdb_store.test.cpp

@@ -5,6 +5,7 @@
 #include <cstdlib>
 #include <filesystem>
 #include <stdexcept>
+#include <thread>
 #include <vector>
 
 #include "barretenberg/common/serialize.hpp"

barretenberg/cpp/src/barretenberg/crypto/merkle_tree/signal.hpp

@@ -4,27 +4,27 @@
 
 namespace bb::crypto::merkle_tree {
 /**
- * @brief Used in parallel insertions in the the IndexedTree. Workers signal to other following workes as they move up
+ * @brief Used in parallel insertions in the IndexedTree. Workers signal to other following workes as they move up
  * the level of the tree.
  *
  */
 class Signal {
   public:
-    Signal(uint32_t initial_level = 1)
-        : signal_(initial_level){};
+    explicit Signal(uint32_t initial_level = 1)
+        : signal_(std::make_unique<std::atomic<uint32_t>>(initial_level)){};
     ~Signal() = default;
     Signal(const Signal& other)
-        : signal_(other.signal_.load())
+        : signal_(std::make_unique<std::atomic<uint32_t>>(other.signal_->load()))
     {}
-    Signal(const Signal&& other) = delete;
+    Signal(Signal&& other) = default;
     Signal& operator=(const Signal& other)
     {
         if (this != &other) {
-            signal_.store(other.signal_.load());
+            signal_->store(other.signal_->load());
         }
         return *this;
     }
-    Signal& operator=(const Signal&& other) = delete;
+    Signal& operator=(Signal&& other) = default;
 
     /**
      * @brief Causes the thread to wait until the required level has been signalled
@@ -33,10 +33,10 @@ class Signal {
      */
     void wait_for_level(uint32_t level = 0)
     {
-        uint32_t current_level = signal_.load();
+        uint32_t current_level = signal_->load();
         while (current_level > level) {
-            signal_.wait(current_level);
-            current_level = signal_.load();
+            signal_->wait(current_level);
+            current_level = signal_->load();
         }
     }
 
@@ -47,17 +47,18 @@ class Signal {
      */
     void signal_level(uint32_t level = 0)
     {
-        signal_.store(level);
-        signal_.notify_all();
+        signal_->store(level);
+        signal_->notify_all();
     }
 
     void signal_decrement(uint32_t delta = 1)
     {
-        signal_.fetch_sub(delta);
-        signal_.notify_all();
+        signal_->fetch_sub(delta);
+        signal_->notify_all();
     }
 
   private:
-    std::atomic<uint32_t> signal_;
+    // apple clang has issues if this cannot be move-constructed, so we wrap in unique_ptr
+    std::unique_ptr<std::atomic<uint32_t>> signal_;
 };
 } // namespace bb::crypto::merkle_tree

barretenberg/cpp/src/barretenberg/crypto/merkle_tree/types.hpp

@@ -1,6 +1,6 @@
 #pragma once
 
-#include <cstdint>
+#include <cstddef>
 namespace bb::crypto::merkle_tree {
-using index_t = uint64_t;
+using index_t = size_t;
 } // namespace bb::crypto::merkle_tree

barretenberg/cpp/src/barretenberg/sumcheck/sumcheck.hpp

@@ -431,13 +431,9 @@ polynomials that are sent in clear.
 
         std::vector<FF> libra_evaluations;
         libra_evaluations.reserve(multivariate_d);
-        zk_sumcheck_data = ZKSumcheckData<Flavor>(eval_masking_scalars,
-                                                  masking_terms_evaluations,
-                                                  libra_univariates,
-                                                  libra_scaling_factor,
-                                                  libra_challenge,
-                                                  libra_running_sum,
-                                                  libra_evaluations);
+        zk_sumcheck_data = ZKSumcheckData<Flavor>{ eval_masking_scalars, masking_terms_evaluations, libra_univariates,
+                                                   libra_scaling_factor, libra_challenge,           libra_running_sum,
+                                                   libra_evaluations };
     };
 
     /**

barretenberg/cpp/src/barretenberg/vm/avm/tests/helpers.test.cpp

@@ -3,7 +3,6 @@
 #include "barretenberg/vm/avm/trace/helper.hpp"
 #include "barretenberg/vm/constants.hpp"
 #include "common.test.hpp"
-#include <bits/utility.h>
 
 namespace tests_avm {
 

barretenberg/cpp/src/barretenberg/vm/avm/tests/slice.test.cpp

@@ -100,7 +100,7 @@ class AvmSliceTests : public ::testing::Test {
         }
 
         // Check that the extra final row is well-formed.
-        EXPECT_THAT(trace.at(static_cast<size_t>(last_row_idx + 1)),
+        EXPECT_THAT(trace.at(static_cast<uint64_t>(last_row_idx + 1)),
                     AllOf(SLICE_ROW_FIELD_EQ(addr, FF(dst_offset) + FF(copy_size)),
                           SLICE_ROW_FIELD_EQ(col_offset, col_offset + copy_size),
                           SLICE_ROW_FIELD_EQ(cnt, 0),