Use aligned buffer in tests

These tests failed verify_alignment under miri. I suspect they were
passing not under miri because the allocator happened to
overalign.

Author: dzfranklin

capnp/src/serialize/no_alloc_slice_segments.rs

@@ -319,7 +319,7 @@ mod tests {
     use crate::{
         message::{ReaderOptions, ReaderSegments},
         serialize::{self, no_alloc_slice_segments::calculate_data_offset},
-        OutputSegments, Word,
+        word, OutputSegments, Word,
     };
 
     use super::{
@@ -465,15 +465,16 @@ mod tests {
     #[test]
     fn test_no_alloc_buffer_segments_message_postfix() {
         let output_segments = OutputSegments::SingleSegment([&[1, 2, 3, 4, 5, 6, 7, 8]]);
-        let mut buf = vec![];
-        serialize::write_message_segments(&mut buf, &output_segments).unwrap();
-        buf.extend_from_slice(&[11, 12, 13, 14, 15, 16]);
+        let mut buf = Word::allocate_zeroed_vec(2);
+        serialize::write_message_segments(Word::words_to_bytes_mut(&mut buf), &output_segments)
+            .unwrap();
+        buf.push(word(11, 12, 13, 14, 15, 16, 0, 0));
 
-        let remaining = &mut buf.as_slice();
+        let remaining = &mut Word::words_to_bytes(&buf);
         NoAllocSliceSegments::try_new(remaining, ReaderOptions::new()).unwrap();
 
         // Confirm that slice pointer was advanced to data past first message
-        assert_eq!(*remaining, &[11, 12, 13, 14, 15, 16]);
+        assert_eq!(*remaining, &[11, 12, 13, 14, 15, 16, 0, 0]);
     }
 
     #[test]

capnpc/test/test.rs

@@ -89,7 +89,7 @@ mod tests {
     use crate::test_util::{init_test_message, CheckTestMessage};
     use capnp::message::ReaderOptions;
     use capnp::message::{self, TypedBuilder, TypedReader};
-    use capnp::{primitive_list, text};
+    use capnp::{primitive_list, text, Word};
 
     // like the unstable std::assert_matches::assert_matches but doesn't
     // require $left implement Debug
@@ -2123,11 +2123,16 @@ mod tests {
         CheckTestMessage::check_test_message(typed_builder.get_root().unwrap());
         CheckTestMessage::check_test_message(typed_builder.get_root_as_reader().unwrap());
 
-        let mut buffer = vec![];
-        capnp::serialize::write_message(&mut buffer, typed_builder.borrow_inner()).unwrap();
+        let mut buffer = Word::allocate_zeroed_vec(512);
+
+        capnp::serialize::write_message(
+            Word::words_to_bytes_mut(&mut buffer),
+            typed_builder.borrow_inner(),
+        )
+        .unwrap();
 
         let reader = capnp::serialize::read_message_from_flat_slice(
-            &mut buffer.as_slice(),
+            &mut Word::words_to_bytes(&buffer),
             ReaderOptions::new(),
         )
         .unwrap();
@@ -2145,11 +2150,16 @@ mod tests {
         CheckTestMessage::check_test_message(typed_builder.get_root().unwrap());
         CheckTestMessage::check_test_message(typed_builder.get_root_as_reader().unwrap());
 
-        let mut buffer = vec![];
-        capnp::serialize::write_message(&mut buffer, typed_builder.borrow_inner()).unwrap();
+        let mut buffer = Word::allocate_zeroed_vec(512);
+
+        capnp::serialize::write_message(
+            Word::words_to_bytes_mut(&mut buffer),
+            typed_builder.borrow_inner(),
+        )
+        .unwrap();
 
         let reader = capnp::serialize::read_message_from_flat_slice_no_alloc(
-            &mut buffer.as_slice(),
+            &mut Word::words_to_bytes(&buffer),
             ReaderOptions::new(),
         )
         .unwrap();