Cant build example

[lukaseller]

I have a problem with the following example .

I copied the source code in my lib.rs

#![feature(specialization)]

#[macro_use]
extern crate pyo3;

use pyo3::prelude::*;

#[pyfunction]
/// Formats the sum of two numbers as string
fn sum_as_string(a: usize, b: usize) -> PyResult<String> {
    Ok((a + b).to_string())
}

/// This module is a python moudle implemented in Rust.
#[pymodule]
fn rust_py(py: Python, m: &PyModule) -> PyResult<()> {
    m.add_wrapped(wrap_function!(sum_as_string))?;

    Ok(())
}

And set my cargo.toml file to:

[package]
name = "rust-py"
version = "0.1.0"

[lib]
name = "rust_py"
crate-type = ["cdylib"]

[dependencies.pyo3]
version = "0.5.2"
features = ["extension-module"]

When I do :

cargo rustc --release -- -C link-arg=-undefined -C link-arg=dynamic_lookup

I get the following error regarding the pymodule argument:

error[E0658]: The attribute pymodule is currently unknown to the compiler and may have meaning added to it in the future (see issue #29642)

My setup:

• MacOs 10.14
• rustc 1.32.0-nightly

Any ideas what could be the issue? Thanks

[konstin]

The problem is that you're using the documentation for master, while building on stable (0.5.2). stable docs

[lukaseller]

Thank you for your help!
But it seems that there is another issue:

error[E0119]: conflicting implementations of trait `python::IntoPyDictPointer` for type `(_, _)`:
   --> /Users/lukas/.cargo/registry/src/github.com-1ecc6299db9ec823/pyo3-0.3.2/src/objects/dict.rs:246:1
    |
231 | / impl <K, V, I> IntoPyDictPointer for I

232 | | where
233 | |     K: ToPyObject,
234 | |     V: ToPyObject,
...   |
243 | |     }
244 | | }
    | |_- first implementation here
245 |
246 |   impl<K: ToPyObject, V: ToPyObject> IntoPyDictPointer for (K, V) {
    |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `(_, _)`
    |
    = note: upstream crates may add new impl of trait `std::iter::Iterator` for type `(_, _)` in future versions

This seems to be related to this issue.
It seems that the stable documentation does still have version 0.3 in the dependencies for the getting started example.

[lukaseller]

Update: It seems to be working with version version = "0.5.2"
I guess changing this to the current version could safe a lot of confusing for people how are just starting out.

Thank you anyway for your great work here :)

[shawn-xy]

Met the same issue. I made it work with git clone the master and add
path = "/path/to/the/cloned/repo" .

[konstin]

I'm sorry for the inconvenience; The problem is that the documentation references 0.3 in the 0.5 documentation. This has been fixed in master (#293), but we can't just make a new release since we've already merged some breaking changes for 0.6.

@shawn-xy Please don't do that. Cargo has sufficient support for git dependencies and for overriding dependencies, which will avoid accidentally forking pyo3.