October 2023 Monthly report

Overview

Thanks again to Open Source Security, inc and Embecosm for their ongoing support for this project.

Milestone Progress

We spent the majority of our time this month preparing patches, or fixing them after receiving reviews on the mailing lists. Some of these patches take a long time to upstream and review, as they touch common complex parts of the GCC project such as the build system, which we are currently fighting with to integrate a new libgrust folder containing various libraries useful to gccrs, such as those related to our procedural macros implementation. These patches are necessary to upstream before the rest of the work done this year, as intrinsic compiler features have been moved to this directory. Once this is done, we will be able to simply push the new patches upstream, after short modifications to make them more suitable to the upstream GCC project. At the moment, there are around 900 patches being prepared, with the hope of pushing them before the end of the month. We are also exploring solutions to help automate this process a little more, as it represents very time consuming work which we would like to avoid in the future - keeping upstream up to date with our development repository, with weekly or bi-weekly updates, should prove worthwhile in the long term.

On the technical side, a lot of bugs were fixed this month again thanks to our contributor team. Jakub Dupak has been making some amazing progress on borrow-checking in gccrs, with the development of a new, simplified intermediate representation specifically designed to interact with the polonius borrow-checker. At the moment, our compiler can start emitting simple errors, such as “use after move” errors:

fn test_move() {
    // this struct cannot be copied
    struct A {
        i: i32,
    }
    let a = A { i: 1 };

    let b = a; // first move
    let c = a; // second move occurs here
}

or simple lifetime analysis:

// this errors out...
fn foo<'a, 'b>(x: &'a usize) -> &'b usize {
    x // we can't know if x will live long enough, so this is an error
}

// ...but this is valid, since we specify that 'a must outlive 'b
fn foo2<'a, 'b>(x: &'a usize) -> &'b usize
    where 'a: 'b
{
    x
}

At the moment, errors are not yet formatted or displayed to the user, but the invalid behavior is caught and the compiler errors out. This work is extremely exciting, and we are looking forward to more progress from Jakub! Great work!

We also got in touch with the GCC release maintainers to understand what was expected of gccrs for it to be an integral part of the GCC 14.1 release, and should be able to fulfill the requirements (println!() macro, simple Rust examples working…). We are very excited for everyone to be able to try the compiler.

Finally, October also saw Pierre-Emmanuel and Arthur go to EuroRust, where they had an amazing time. We are looking forward to coming back next year. We gave a small talk on the compiler, and the challenges of compiling the standard Rust library, which we will link to once released.

Community call

We will have our next monthly community call on the 13th of November

1. You can subscribe to our calendar to see when the next one will be held. The call is open to everyone, even if you would just like to sit-in and listen. You can also subscribe to our mailing-list or join our Zulip chat to be notified of upcoming events.

• jitsi link
• Calendar ID: 7060a0923ffebd3cb52b1afef35a28ff7b64f05962c9af84c23b1847f1f5f894@group.calendar.google.com
• Google calendar link
• iCal link

Completed Activities

• Ast refactor PR2721
• Remove obsolete HIR::BorrowExpr::double_borrow PR2719
• Parse const with no value PR2708
• Fix overridden virtual method modifier PR2707
• Compile pattern match statements into conditional statements PR2705
• BIR PR2702
• HIR cleanup and refactor PR2697
• Fix token lexed as a float literal PR2694
• libgrust: Add changelog, maintainers PR2692
• 2688 labelled block PR2689
• Fix pub unit type parsing PR2686
• Fix macro fragment follow set PR2685
• Make resolution of ```AssociatedItem``` instances polymorphic PR2683
• Make lowering of ```AssociatedItem``` instances polymorphic PR2682
• gccrs: minor changes (typo and minor refactor) PR2681
• Create base class ```AssociatedItem``` PR2679
• Fix parse mut ref PR2678
• Replace ```get<sub>patternnodeid</sub>``` with ```get<sub>nodeid</sub>``` PR2677
• Accept `macro<sub>rules</sub>` name for a macro rule. PR2675
• Fix macro “default” call at item level PR2674
• Fix closure in closure parsing PR2673
• Fix RangeFromExpr parsing in for loop PR2672
• Fix expression segment parsing PR2671
• Fix global path parsing PR2668
• Rename cloning methods in ```TupleStructItems``` and ```TuplePatternItems``` PR2661
• Tyty cast api PR2647
• Fix parser bug on tupplestruct pattern PR2646
• Remove unnecessary “empty vector” comments PR2644
• Adjust methods for ```TuplePatternItems``` to match ```TupleStructItems``` PR2643
• Fix type confusion in coercion PR2642
• Add tests for v0 mangling PR2637
• Initial implementation of v0 mangling PR2615
• Export proc macros in proc macro crates PR2603

Contributors this month

• Rizan F (new contributor!)
• Jakub Dupak
• Marc Poulhiès
• Owen Avery
• Raiki Tamura

Overall Task Status

Test Cases

Bugs

Milestones Progress

Testing project

Planned Activities

• Opaque types
• Drop marker trait

Detailed changelog