GCC Front-End For Rust

Alternative Rust Compiler for GCC

View the Project on GitHub

February 2024 Monthly report


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

Project update

We have had an influx of potential GSoC applicants this month, with lots of new people joining our Zulip channel and GitHub repository. They have submitted a large number of pull-requests, and have started heavily participating in the compiler development chat - which we are really happy about! The potential applicants seem very motivated and eager to work on the project, which is very nice to see. Thank you all for your interest!

As a consequence, the amount of contributions has picked up - similarly to past years around this period. This increases our review load, but is also very productive.

On the upstream side, the tooling we had been working on is working nicely and speeding up the creation and testing of these commits. We are still going to improve it, but it is already proving to be useful. Since last month, we have upstreamed two patchsets in three weeks, with one more patchset being prepared for this week. This has enabled us to catch some minor issues we would not have discovered until much later, thanks to the wide range of architectures used by the GCC community.

Regarding technical contributions, progress continued on the borrow checker with multiple large pull-requests from Jakub currently being reviewed. These pull-requests concern the addition of variance analysis to the project, as well as the emission of more facts for the polonius-engine crate.

We have also made great progress on format_args!(), with the proper expansion of these macro invocations to their runtime components. Once these components are properly generated, it is relatively easy to implement the famous println!() macro - iterate on those components, calling the associated formatting function each time, and using stdout as a writer. Thanks to the work done by Philip on iterators, we are now able to have a functioning, but unoptimized println!() with gccrs - which is a huge milestone! Please note that the real println!() macro is a member of the std crate, not core, as it relies on dynamic allocation and locking in order to ensure a fast and safe access to the global operating system output streams.

A couple issues remain around the parsing of the format_args!() arguments, but we are expecting to take care of them soon. We will have to polish the integration of the Rust component responsible for parsing the format_args!() invocation, as there are build system subtleties to take in account.

We will soon get in touch with the GCC release maintainers in order to prepare this upcoming release, with the expectation of our frontend being part of GCC 14.1.

We would like to remind our readers that Jakub Dupak, one of our contributors working on integrating the polonius borrow-checker to gccrs, is currently finishing studying for his Master’s Degree and is looking for sponsorship to continue his work on the borrow checker. Please get in touch if you or your company would be interested in funding his work!

Community call

We will have our next monthly community call on the 18th of March at 10am UTC. 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.

Call for contribution

This is a new section for particularly easy or interesting issues we would like folks external to the project to contribute to. We are available for mentoring and guiding you on their resolution. This is a great way to start making your mark on a complex project such as this one and to learn a lot in the process!

Derive macros (invoked through the #[derive(...)] attribute) should only be applied on type declarations - new structures, enumerations or unions. We need to report an error to the user when they try using such a macro on a non-type-declaration element - such as a function or trait.

The provided playground link (see the issue) showcases the expected behavior. The code it contains will need to be added as a test case to the project, with other test cases welcome.

This contribution will touch on our AST, our highest level intermediate representation in the compiler.

Check out our Contributing guidelines to get started on them or feel free to send us a message on Zulip or IRC!

Completed Activities

Contributors this month

Overall Task Status

Category Last Month This Month Delta
TODO 266 276 +10
In Progress 66 74 +8
Completed 798 812 +14

Test Cases

TestCases Last Month This Month Delta
Passing 8365 8402 +37
Failed - - -
XFAIL 69 69 -
XPASS - - -


Category Last Month This Month Delta
TODO 95 97 +2
In Progress 36 37 +1
Completed 406 411 +5

Milestones Progress

Milestone Last Month This Month Delta Start Date Completion Date Target
GCC 14.1 Release 0% 71% +71% TBD - 15th Apr 2024
AST Pipeline for libcore 1.49 78% 82% +4% 13th Apr 2023 - 15th Apr 2024
HIR Pipeline for libcore 1.49 69% 72% +3% 13th Apr 2023 - TBD
core 1.49 functionality [AST] 4% 8% +4% 1st Jul 2023 - 15th Apr 2025
formatargs!() support 0% 60% +60% 15th Feb 2024 - 1st Apr 2024
Name Resolution rework 0% 0% - 15th Feb 2024 - 1st Apr 2024
Upcoming Milestone Last Month This Month Delta Start Date Completion Date Target
Rustc Testsuite Prerequisistes 0% 0% - TBD - 1st Feb 2024
Intrinsics and builtins 18% 18% - 6th Sep 2022 - 1st Apr 2025
Const Generics 2 0% 0% - TBD - 15th Dec 2024
Rust-for-Linux compilation 0% 0% - TBD - 1st Apr 2025
Procedural Macros 2 57% 57% - TBD - 15th Dec 2024
Borrow Checking 2 0% 0% - TBD - 15th Apr 2025
Past Milestone Last Month This Month Delta Start Date Completion Date Target
Data Structures 1 - Core 100% 100% - 30th Nov 2020 27th Jan 2021 29th Jan 2021
Control Flow 1 - Core 100% 100% - 28th Jan 2021 10th Feb 2021 26th Feb 2021
Data Structures 2 - Generics 100% 100% - 11th Feb 2021 14th May 2021 28th May 2021
Data Structures 3 - Traits 100% 100% - 20th May 2021 17th Sep 2021 27th Aug 2021
Control Flow 2 - Pattern Matching 100% 100% - 20th Sep 2021 9th Dec 2021 29th Nov 2021
Macros and cfg expansion 100% 100% - 1st Dec 2021 31st Mar 2022 28th Mar 2022
Imports and Visibility 100% 100% - 29th Mar 2022 13th Jul 2022 27th May 2022
Const Generics 100% 100% - 30th May 2022 10th Oct 2022 17th Oct 2022
Initial upstream patches 100% 100% - 10th Oct 2022 13th Nov 2022 13th Nov 2022
Upstream initial patchset 100% 100% - 13th Nov 2022 13th Dec 2022 19th Dec 2022
Update GCC’s master branch 100% 100% - 1st Jan 2023 21st Feb 2023 3rd Mar 2023
Final set of upstream patches 100% 100% - 16th Nov 2022 1st May 2023 30th Apr 2023
Borrow Checking 1 100% 100% - TBD 8th Jan 2024 15th Aug 2023
Procedural Macros 1 100% 100% - 13th Apr 2023 6th Aug 2023 6th Aug 2023
GCC 13.2 Release 100% 100% - 13th Apr 2023 22nd Jul 2023 15th Jul 2023
GCC 14 Stage 3 100% 100% - 1st Sep 2023 20th Sep 2023 1st Nov 2023

Testing project

Testsuite Compiler Last month This month Success delta
rustc testsuite gccrs -fsyntax-only 92.7% 92.7% -
gccrs testsuite rustc stable 59.2% 59.2% -
rustc testsuite passing tests gccrs 14.0% 14.0% -
rustc testsuite (nostd) gccrs 27.5% 27.5% -
rustc testsuite (nocore) gccrs 3.8% 3.8% -
blake3 gccrs 25.0% 25.0% -
libcore gccrs 0% 0% -

Planned Activities


Risk Impact (1-3) Likelihood (0-10) Risk (I * L) Mitigation
Missing features for GCC 14.1 deadline 2 3 6 Start working on required features early

Detailed changelog