Default behavior does not insert synthetic parens for precedence

[fowles]

prettyplease will generate rust code that does not accurately reflect the Expr tree that goes into it. There is a workaround using to_token_stream.

  let mut file = syn::File {
    shebang: None,
    attrs: vec![],
    items: vec![],
  };
  let mut func: syn::ItemFn = parse_quote!(fn foo(n: i32) -> i32 { });
  let lhs: syn:Expr = parse_quote!(n + n);
  let rhs: syn:Expr = parse_quote!(n + n);
  func.block.stmts.push(
    syn::ExprBinary {
      attrs: vec![],
      op: parse_quote!(*),
      left: Box::new(lhs),
      right: Box::new(rhs),
    }
    .into()
  );

  let pretty_direct = prettyplease::unparse(&file);
  // INCORRECT: fn foo(n: i32) -> i32 { n + n * n + n }

  let munged: syn::File = syn::parse2(rust.to_token_stream()).unwrap();
  let pretty_indirect =  prettyplease::unparse(&munged)).unwrap();
  // CORRECT: fn foo(n: i32) -> i32 { (n + n) * (n + n) }

Apologies if this doesn't quite compile, but it should give you the general gist of the issue.

[fowles]

Do the owners consider this a bug? If so, would they be amenable to PRs fixing it?