Fix some Clippy warnings

src/decoder.rs

@@ -76,10 +76,8 @@ impl Decoder {
         }
 
         let mut result = vec![];
-        for block in self.blocks.iter() {
-            if let Some(block) = block {
-                result.extend(block);
-            }
+        for block in self.blocks.iter().flatten() {
+            result.extend(block);
         }
 
         result.truncate(self.config.transfer_length() as usize);
@@ -102,10 +100,8 @@ impl Decoder {
         }
 
         let mut result = vec![];
-        for block in self.blocks.iter() {
-            if let Some(block) = block {
-                result.extend(block);
-            }
+        for block in self.blocks.iter().flatten() {
+            result.extend(block);
         }
         result.truncate(self.config.transfer_length() as usize);
         Some(result)

src/pi_solver.rs

@@ -1189,14 +1189,13 @@ impl<T: BinaryMatrix> IntermediateSymbolDecoder<T> {
     }
 
     fn record_fma_rows(&mut self, i: usize, iprime: usize, beta: Octet) {
+        self.debug_symbol_add_ops += 1;
         if beta == Octet::one() {
-            self.debug_symbol_add_ops += 1;
             self.deferred_D_ops.push(SymbolOps::AddAssign {
                 dest: self.d[iprime],
                 src: self.d[i],
             });
         } else {
-            self.debug_symbol_add_ops += 1;
             self.debug_symbol_mul_ops += 1;
             self.deferred_D_ops.push(SymbolOps::FMA {
                 dest: self.d[iprime],
@@ -1312,7 +1311,7 @@ impl<T: BinaryMatrix> IntermediateSymbolDecoder<T> {
             reorder.push(*i);
         }
 
-        let mut operation_vector = std::mem::replace(&mut self.deferred_D_ops, vec![]);
+        let mut operation_vector = std::mem::take(&mut self.deferred_D_ops);
         operation_vector.push(SymbolOps::Reorder { order: reorder });
         return (Some(result), Some(operation_vector));
     }

src/sparse_matrix.rs

@@ -258,7 +258,7 @@ impl BinaryMatrix for SparseBinaryMatrix {
     }
 
     fn get_ones_in_column(&self, col: usize, start_row: usize, end_row: usize) -> Vec<u32> {
-        assert_eq!(self.column_index_disabled, false);
+        assert!(!self.column_index_disabled);
         #[cfg(debug_assertions)]
         debug_assert!(self.debug_indexed_column_valid[col]);
         let physical_col = self.logical_col_to_physical[col];
@@ -321,7 +321,7 @@ impl BinaryMatrix for SparseBinaryMatrix {
             i,
             "Can only freeze the last sparse column"
         );
-        assert_eq!(self.column_index_disabled, false);
+        assert!(!self.column_index_disabled);
         self.num_dense_columns += 1;
         let (last_word, _) = self.bit_position(self.height - 1, self.num_dense_columns - 1);
         // If this is in a new word