Merge pull request aeron-io#518 from ZackPierce/simplify_done_output

[Rust] Simplify done unwrapping to prevent dual mutable aliasing

Author: tmontgomery

rust/car_example/src/main.rs

@@ -139,10 +139,10 @@ fn decode_car_and_assert_expected_content(buffer: &[u8]) -> CodecResult<()> {
  println!("Activation Code: {}", activation_code);
  assert_eq!("abcdef", activation_code);
 
- let (position, buffer_back) = dec_done.unwrap();
+ let position = dec_done.unwrap();
  println!("Finished decoding. Made it to position {0} out of {1}",
  position,
- buffer_back.len());
+ buffer.len());
  Ok(())
 }
 
@@ -202,7 +202,7 @@ fn encode_car_from_scratch() -> CodecResult<Vec<u8>> {
  let enc_model = enc_manufacturer.manufacturer("Honda".as_bytes())?;
  let enc_activation_code = enc_model.model("Civic VTi".as_bytes())?;
  let done = enc_activation_code.activation_code("abcdef".as_bytes())?;
- let (pos, _) = done.unwrap();
+ let pos = done.unwrap();
  pos
  };
  println!("encoded up to position {}", used_pos);

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/rust/RustCodecType.java

@@ -118,11 +118,10 @@ String generateDoneCoderType(
  {
  appendScratchWrappingStruct(writer, doneTypeName);
  RustGenerator.appendImplWithLifetimeHeader(writer, doneTypeName);
- writer.append(INDENT).append(String.format("pub fn unwrap(mut self) -> (usize, &%s%s [u8]) {\n",
- DATA_LIFETIME, this == Encoder ? " mut" : ""))
- .append(INDENT).append(INDENT).append(format("(self.%s.pos, self.%s.data)\n",
- scratchProperty(), scratchProperty()))
- .append(INDENT).append("}\n");
+ indent(writer, 1, "/// Returns the number of bytes %s\n", this == Encoder ? "encoded" : "decoded");
+ indent(writer, 1, "pub fn unwrap(self) -> usize {\n");
+ indent(writer, 2, "self.%s.pos\n", scratchProperty());
+ indent(writer, 1, "}\n");
 
  appendWrapMethod(writer, doneTypeName);
  writer.append("}\n");