PascalCase -> snake_case for consistency with the rest of the codebase.

src/nnue/features/enpassant.cpp

@@ -5,8 +5,10 @@
 namespace Eval::NNUE::Features {
 
     // Get a list of indices with a value of 1 among the features
-    void EnPassant::AppendActiveIndices(
-        const Position& pos, Color /* perspective */, IndexList* active) {
+    void EnPassant::append_active_indices(
+        const Position& pos,
+        Color /* perspective */,
+        IndexList* active) {
 
         // do nothing if array size is small to avoid compiler warning
         if (RawFeatures::kMaxActiveDimensions < kMaxActiveDimensions)
@@ -21,9 +23,11 @@ namespace Eval::NNUE::Features {
     }
 
     // Get a list of indices whose values ​​have changed from the previous one in the feature quantity
-    void EnPassant::AppendChangedIndices(
-        const Position& pos, Color /* perspective */,
-        IndexList* removed, IndexList* added) {
+    void EnPassant::append_changed_indices(
+        const Position& pos,
+        Color /* perspective */,
+        IndexList* removed,
+        IndexList* added) {
 
         auto previous_epSquare = pos.state()->previous->epSquare;
         auto epSquare = pos.state()->epSquare;