0.3.0 doesn't support macro invocation in default values

[cbiffle]

I have some code using 0.2.0 that does things like this:

#[derive(SmartDefault)]
struct Test {
    #[default = "vec![0; 100]"]
    field: Vec<u32>,
}

In 0.3.0 this fails to parse with either syntax:

#[derive(SmartDefault)]
struct Test {
    #[default(vec![0; 100])]
    field: Vec<u32>,
    // unexpected token: !
}
#[derive(SmartDefault)]
struct Test2 {
    #[default = vec![0; 100]]
    field: Vec<u32>,
    // expected ']', found '!'
}

This is preventing me from upgrading my codebase from 0.2.0 -- which isn't a huge deal, since 0.2.0 works fine, but it's adding a dependency on old versions of syn/quote so I'd like to upgrade.

[idanarye]

which isn't a huge deal

It is actually - 0.2.0 uses an older version of syn that does not support Rust 2018, so you can't have Rust 2018 syntax in your struct.

To support macro invocation with the new style, I'll need the still unstable unrestricted_attribute_tokens feature. Using it with the feature gate doesn't currently work, but it does work if I change the syn features to "full" - so that's an easy fix. Still - I don't want to have this available only on nightly...

I can add the string version as a special argument. How about this?

    #[default(_txt = "vec![0; 100]")]
    field: Vec<u32>,

[cbiffle]

Good point! That syntax would cover my use case. I'd suggest code or _code for the name to make its purpose more obvious.

[cbiffle]

Fantastic! Thank you!

[idanarye]

Wait - I just pushed to commit, but I did not upload the version to crates.io yet. I'm waiting for the Travis build to finish.

[cbiffle]

Understood -- the "thank you" was for working on it so swiftly. :-)

[idanarye]

@cbiffle OK, it's uploaded. Upgrade to 0.4.0 and you are good to go.