can not make functions public with `compose!`

[vitiral]

I can't seem to make a function public

prop_compose! {
    pub fn arb_raw_name()(ref s in GEN_NAME_RE) -> String {                                                                                                                                                       
        s.to_string()                                                                                                                                                                                             
    }                                                                                                                                                                                                             
} 

has this error when compiled:

error: no rules expected the token `pub`
  --> src/test_name.rs:40:5
   |
40 |     pub fn arb_raw_name()(ref s in GEN_NAME_RE) -> String {

[vitiral]

I got to hand it to you, this is one of the most well designed and documented libraries I've ever had the pleasure of working with. I'm about an hour in and the workarond is pretty obvious:

pub fn arb_raw_name() -> BoxedStrategy<String> {
    GEN_NAME_RE
        .prop_map(|s| s.to_string())
        .boxed()
}

Not that this isn't still a bug, but serious props to the entire architecture. I was using quickcheck, which I thought was quite excelent, but this is leagues beyond. Seriously well done.

[AltSysrq]

The macro predates the vis fragment specifier (and there's still no way to match modifiers in general), so it uses a hack like this:

proptest_compose! {
    [pub] fn foo()(v in prop::num::usize::ANY) -> usize { 
        // ... 
    }
}

I will look into supporting vis as well so it "just works", probably after I get back from vacation.

[vitiral]

it's not a super big emergency, I kind of like being explicit actually just figured you would appreciate the bug report

[AltSysrq]

It looks like the vis fragment specifier for macros is not yet stable, so supporting it will need to wait for now. (It would be possible to have a nightly-only feature, but it would be awkward to implement and client code would need to opt-in to it, which is more work than just using the brackets for the time being.)

[vitiral]

I don't think a nightly-only feature is worth it. Thanks!

[ornamentist]

New to Rust and proptest and have the same issue with the compose macro making only private functions. Also very impressed at the level of documentation and thought that has gone into proptest.

Can I ask whether the "GEN_NAME_RE" in the @vitiral workaround is a user-defined constant or a proptest constant? An example workaround function in context would be very useful.

[AltSysrq]

the compose macro making only private functions

As I mentioned above, you can make them, just not with standard rust syntax since the macro can't match them. E.g., the following compiles:

#![allow(dead_code)]

#[macro_use] extern crate proptest;

mod one {
    prop_compose! {
        [pub] fn two_ints()(a in 0..10, b in 0..20) -> (i32, i32) {
            (a, b)
        }
    }
}

mod two {
    use super::one::two_ints;

    proptest! {
        // commented so it always gets compiled for this example
        //#[test]
        fn test_something(_a in two_ints()) {
            // ...
        }
    }
}

fn main() { }

Can I ask whether the "GEN_NAME_RE" … is a user-defined constant or a proptest constant?

It's user-defined. From other conversations I believe it is a string literal (i.e., a regex-based strategy).

[ornamentist]

Many thanks, that's exactly what I was looking for.

[Centril]

Update: The vis matcher was stabilized in rust-lang/rust#53702 which hits stable in 1.30.

[AltSysrq]

As of 0.9.0, visibility modifiers can be used directly.