Use Vec::resize instead of manually re-implementing it

Author: marmeladema

capnp/src/private/layout_test.rs

@@ -29,12 +29,8 @@ fn test_at_alignments(words: &[crate::Word], verify: &dyn Fn(PointerReader)) {
         let mut unaligned_data = Vec::with_capacity((words.len() + 1) * 8);
         for offset in 0..8 {
             unaligned_data.clear();
-            for _ in 0..offset {
-                unaligned_data.push(0);
-            }
-            for b in crate::Word::words_to_bytes(words) {
-                unaligned_data.push(*b);
-            }
+            unaligned_data.resize(offset, 0);
+            unaligned_data.extend(crate::Word::words_to_bytes(words));
             verify(PointerReader::get_root_unchecked((unaligned_data[offset..]).as_ptr()));
         }
     }

capnp/src/serialize.rs

@@ -382,9 +382,7 @@ fn flatten_segments<R: message::ReaderSegments + ?Sized>(segments: &R) -> Vec<u8
     let segment_count = segments.len();
     let table_size = segment_count / 2 + 1;
     let mut result = Vec::with_capacity(word_count);
-    for _ in 0..(table_size * BYTES_PER_WORD) {
-        result.push(0);
-    }
+    result.resize(table_size * BYTES_PER_WORD, 0);
     {
         let mut bytes = &mut result[..];
         write_segment_table_internal(&mut bytes, segments).expect("Failed to write segment table.");