Combining env and flag arguments doesn't work as expected

[Kerollmops]

When we add the env attribute on a boolean field, the command line argument, that must be considered as a flag, is considered as an attribute requiring a value.

#[derive(StructOpt)]
pub struct Opt {
    /// Do not send analytics.
    #[structopt(long, env = "NO_ANALYTICS")]
    pub no_analytics: bool,
}

Here is what StructOpt generate with the above configuration:

xxx-http 0.8.4

USAGE:
    xxx [OPTIONS]

FLAGS:
    -h, --help       Prints help information
    -V, --version    Prints version information

OPTIONS:
        --no-analytics <no-analytics>    Do not send analytics. [env: NO_ANALYTICS=]

And here is what I expected:

xxx-http 0.8.4

USAGE:
    xxx [OPTIONS]

FLAGS:
    -h, --help             Prints help information
        --no-analytics     Do not send analytics. [env: NO_ANALYTICS]
    -V, --version          Prints version information

Is this behavior expected or is it not? Thank you for you help.

[CreepySkeleton]

It isn't really clear what the expected behavior is from your comment. I'm going to assume it's all about

• flags (long bool fields) do not take any value, the very fact --no-analytics is present raises the flag. This is true in structopt
• environment fallbacks for flags don't take any value. More specifically, the very fact the fallback env is defined (i.e you have export NO_ANALYTICS="" someplace above/before) raises the flag, no matter what the env is assigned with.

Now, let's remember that structopt works on top of clap. If you use some feature with structopt - this feature must be available in clap in the first place. I believe what you're asking for is not possible with clap because Arg::env implies Arg::takes_value(true). Even if you reset takes_value(false) back it won't work, unfortunately.

I'm closing this since it's entirely about clap, structopt has nothing to do with it.

Btw, there is such a request in clap already.

[Kerollmops]

Ho! I already checked if it there was a related issue on Clap and didn't find anything.
I fallback on the issue page of StructOpt because I thought it was done by it, which is a dumb thought as this is clearly Clap which produces this help message.

I apologize and subscribed to the clap issue at the same time :) Thank you!