1.70.0: Type inference no longer works in conjunction with Glib's clone macro #112225
Description
My code does not compile any more after updating to 1.70.0. The project can be found here
Code
I tried to create a minimal reproducer. It has something to do with glib's clone macro, which I use. Here is the reproducer that compiles fine on 1.69 but not on 1.70.0. I left some comments in the code describing what I observed so far. It needs glib and futures dependency):
use futures::Future; use glib::clone; fn main() { let obj = String::new(); do_async( // just using `compound()` without `async` block works async { compound().await }, clone!(@strong obj => move |info| if let Ok(info) = info { // removing this line makes the code compile println!("{:?}", info.t); }), ); } struct Compound { t: i32 } // Just returning a simple type like i32 makes the code compile async fn compound() -> Result<Compound, ()> { Err(()) } async fn do_async<R, Fut, F>(tokio_fut: Fut, glib_closure: F) where R: Send + 'static, Fut: Future<Output = R> + Send + 'static, F: FnOnce(R) + 'static, { glib_closure(tokio_fut.await); }Output
error[E0282]: type annotations needed for `Result<_, E>` --> src/main.rs:9:37 | 9 | clone!(@strong obj => move |info| if let Ok(info) = info { | ^^^^ 10 | // removing this line makes the code compile 11 | println!("{:?}", info.t); | ---- type must be known at this point | help: consider giving this closure parameter an explicit type, where the placeholders `_` are specified | 9 | clone!(@strong obj => move |info: Result<_, E>| if let Ok(info) = info { | ++++++++++++++ For more information about this error, try `rustc --explain E0282`. I expected to see this happen: The type info is correctly inferred
Instead, this happened: The compiler tells me that it doesn't know the type, although the type can be inferred
Version it worked on
It most recently worked on: 1.69.0
Version with regression
rustc --version --verbose:
rustc 1.70.0 (90c541806 2023-05-31) binary: rustc commit-hash: 90c541806f23a127002de5b4038be731ba1458ca commit-date: 2023-05-31 host: x86_64-unknown-linux-gnu release: 1.70.0 LLVM version: 16.0.2