version = expr ignored, and incorrectly uses env!(CARGO_PKG_VERSION)

[matsadler]

Setting #[structopt(version = expr)] (where expr is any expression, but not a literal) the expression is ignored and env!(CARGO_PKG_VERSION) is used instead.

It looks like the problem is clap::App::version is being called twice, first time with expr, and second time with the value of CARGO_PKG_VERSION, and the second call wins. In the expanded macro output I'm seeing something like:

let app = ::structopt::clap::App::new("example")
    .version(VERSION)
    .version("0.1.0");

Here is a reduction of my code that's seeing the problem:

use structopt::StructOpt;

const VERSION: &str = "custom version";

#[derive(StructOpt)]
#[structopt(version = VERSION)]
pub struct Opts {}

fn main() {
    let _ = Opts::from_args();
}

As a workaround I can set #[structopt(no_version, version = VERSION)] and get the result I want, although looking at structopt_derive::attrs::Attrs::top_level_methods it doesn't look like this was intended to work.

[CreepySkeleton]

Right, we'll fix it sometime this week