PatTuple does not add comma for 1-tuple

[jongiddy]

ExprTuple adds a comma to a 1-tuple.PatTuple should also do this to avoid being the same as a PatParen.

The last assert in this test should contain a comma:

#[test]
fn test_one_tuple() {
    let expr_path = ExprPath {
        attrs: Vec::new(),
        qself: None,
        path: Path {
            leading_colon: None,
            segments: [PathSegment {
                ident: Ident::new("a", Span::call_site()),
                arguments: PathArguments::None,
            }].into_iter().collect(),
        },
    };

    let mut expr = ExprTuple {
        attrs: Vec::new(),
        paren_token: token::Paren::default(),
        elems: Punctuated::new(),
    };
    expr.elems.push(Expr::Path(expr_path.clone()));
    assert_eq!(expr.to_token_stream().to_string(), "(a ,)");

    let mut pat = PatTuple {
        attrs: Vec::new(),
        paren_token: token::Paren::default(),
        elems: Punctuated::new(),
    };
    pat.elems.push(Pat::Path(expr_path));
    assert_eq!(pat.to_token_stream().to_string(), "(a)");
}

[dtolnay]

Good catch! I have published a fix in syn 2.0.43.