GCC Front-End For Rust

Alternative Rust Compiler for GCC

View the Project on GitHub

July 2026 Monthly report

Overview

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

Project update

Thanks to the work done by Philip Herron over the last few months, gccrs now supports Generics Associated Types, a required type system feature for both compiling core and the Linux kernel. This feature required massive efforts and was a huge investment into our type system, which needed to be adapted in order for GATs to be fully supported.

We also have made major progress towards our milestone of compiling core this month, with gccrs now being able to fully macro-expand and early name-resolve the crate without erroring out or invalid behavior. We are now dealing with the remaining issues further down the compilation pipeline, and are still progressing towards our objective of being able to compile the Linux kernel in time for RustConf in September. Late name resolution issues should not prove to be too difficult, and we will spend most of our time dealing with type system issues for core. Thankfully, we have already spent a large amount of time identifying type-system issues and reducing them to test cases in our testsuite, so we are hopeful that this work will go smoothly.

In order to fully support multiple crates linking together - as is the case in most Rust projects, but especially in the Linux kernel - Pierre-Emmanuel reworked our entire metadata export and import pass and greatly improved it. Name resolution is now much stronger for multiple crates projects, and merges the results of the resolution together when importing crates. To fix an issue where certain nodes where not being exported into our metadata, as well as some of these exports being incomplete and lacking information, the pass has been moved earlier into the pipeline and now acts on our AST rather than our HIR. While we are still doing a simple and expensive export pass, it is functionally good enough and will be improved later once our main objectives are achieved.

Work on Google Summer of Code continues, with our two students Enes Cevik and Janet Chien progressing admirably on their projects. Both students are extremely productive and nice to work with, and will pass the midterm evaluation with flying colors. Thanks to them, gccrs is now much closer to handling the alloc crate, required for our objective of compiling the Linux kernel, and can also insert Drop calls for a variety of situations - required for properly running the Linux kernel compiled by gccrs. Together, Janet and Enes will bring massive improvements to the compiler over the next two months and we are grateful for their implication and involvment.

Last but not least, Zhi Heng has been working tirelessly on fixing core issues with us in order to get gccrs closer and closer to being a usable compiler. He has worked on C-styl string literals and their memory representation, as they are needed for the Linux kernel, and is now fixing an issue with the way gccrs represents wide pointers when compiling dynamically sized types. Once again, this effort is essential for gccrs to be able to properly compile the kernel and will prove to be extremely useful in the long run.

Call for contribution

Completed Activities

Contributors this month

Overall Task Status

Category Last Month This Month Delta
TODO 409 428 +19
In Progress 118 128 +10
Completed 1255 1272 +17

Bugs

Category Last Month This Month Delta
TODO 191 203 +12
In Progress 52 52 -
Completed 623 630 +7

Test Cases

TestCases Last Month This Month Delta
Passing 10989 11167 +178
Failed - - -
XFAIL 73 73 -
XPASS - - -

Milestones Progress

Here is the list of overarching milestones gccrs is currently targeting. We’ll use the acronym in the following milestone tables, in the column named “OA Milest.”.

Milestone Description Acronym
Embedded Rust 1.49 compiler 0.1 The compiler is able to compile embedded Rust code EC 0.1
Embedded Rust 1.49 compiler 1.0 The compiler is able to compile embedded Rust code and produce valid executables EC 1.0
Rust-for-Linux compiler 0.1 The compiler is able to compile the Linux kernel LC 0.1
Rust-for-Linux compiler 1.0 The compiler is able to compile the Linux kernel and produce a runnable kernel LC 1.0
General purpose Rust 1.49 compiler The compiler passes the Rust 1.49 testsuite, and handles general purpose code GC
Milestone Last Month This Month Delta Start Date Completion Date Target OA Milest.
Rust-for-Linux 35% 40% +5% 1st Nov 2025 - - LC 0.1
Full core Late nameres issues 28% 28% - 1st Dec 2025 - - EC 0.1
Full core Early nameres issues 97% 100% +3% 1st Dec 2025 - - EC 0.1
Full core Typecheck issues 12% 12% - 21st Jan 2026 - - EC 0.1
RfL builderror 100% 100% - - - - LC 0.1
RfL compilerbuiltins 100% 100% - - - - LC 0.1
RfL ffi 40% 40% - - - - LC 0.1
RfL macros 0% 0% - - - - LC 0.1
RfL uapi 0% 0% - - - - LC 0.1
RfL main kernel files 0% 0% - - - - LC 0.1
Upcoming Milestone Last Month This Month Delta Start Date Completion Date Target OA Milest.
Unstable RfL features 0% 0% - 7th Jan 2025 - 1st Aug 2025 LC 0.1
Generic Associated Types 0% 0% - 15th Mar 2025 - 15th Jun 2025 LC 0.1
RfL const generics 0% 0% - 1st May 2025 - 15th Jun 2025 LC 0.1
frontend plugin hooks 0% 0% - 15th May 2025 - 7th Jul 2025 GC
Handling the testsuite issues 0% 0% - 15th Sep 2024 - 15th Sep 2025 GC
main shim 0% 0% - 28th Jul 2025 - 15th Sep 2025 GC
Final core attributes 0% 0% -   -   EC 0.1
Core nightly features 0% 0% -   -   EC 0.1
Defered inference 0% 0% -   -   EC 0.1
Fn traits fixes 0% 0% -   -   EC 0.1
Recursive types 0% 0% -   -   EC 0.1
Drop 0% 0% -   -   EC 1.0
Pin, PinInit 0% 0% -   -   EC 1.0
Past Milestone Last Month This Month Delta Start Date Completion Date Target Target GCC
Data Structures 1 - Core 100% 100% - 30th Nov 2020 27th Jan 2021 29th Jan 2021 GCC 14.1
Control Flow 1 - Core 100% 100% - 28th Jan 2021 10th Feb 2021 26th Feb 2021 GCC 14.1
Data Structures 2 - Generics 100% 100% - 11th Feb 2021 14th May 2021 28th May 2021 GCC 14.1
Data Structures 3 - Traits 100% 100% - 20th May 2021 17th Sep 2021 27th Aug 2021 GCC 14.1
Control Flow 2 - Pattern Matching 100% 100% - 20th Sep 2021 9th Dec 2021 29th Nov 2021 GCC 14.1
Macros and cfg expansion 100% 100% - 1st Dec 2021 31st Mar 2022 28th Mar 2022 GCC 14.1
Imports and Visibility 100% 100% - 29th Mar 2022 13th Jul 2022 27th May 2022 GCC 14.1
Const Generics 100% 100% - 30th May 2022 10th Oct 2022 17th Oct 2022 GCC 14.1
Initial upstream patches 100% 100% - 10th Oct 2022 13th Nov 2022 13th Nov 2022 GCC 14.1
Upstream initial patchset 100% 100% - 13th Nov 2022 13th Dec 2022 19th Dec 2022 GCC 14.1
Update GCC’s master branch 100% 100% - 1st Jan 2023 21st Feb 2023 3rd Mar 2023 GCC 14.1
Final set of upstream patches 100% 100% - 16th Nov 2022 1st May 2023 30th Apr 2023 GCC 14.1
Borrow Checking 1 100% 100% - TBD 8th Jan 2024 15th Aug 2023 GCC 14.1
Procedural Macros 1 100% 100% - 13th Apr 2023 6th Aug 2023 6th Aug 2023 GCC 14.1
GCC 13.2 Release 100% 100% - 13th Apr 2023 22nd Jul 2023 15th Jul 2023 GCC 14.1
GCC 14 Stage 3 100% 100% - 1st Sep 2023 20th Sep 2023 1st Nov 2023 GCC 14.1
GCC 14.1 Release 100% 100% - 2nd Jan 2024 2nd Jun 2024 15th Apr 2024 GCC 14.1
formatargs!() support 100% 100% - 15th Feb 2024 - 1st Apr 2024 GCC 14.1
GCC 14.2 100% 100% - 7th Jun 2024 15th Jun 2024 15th Jun 2024 GCC 14.2
GCC 15.1 100% 100% - 21st Jun 2024 31st Jun 2024 1st Jul 2024 GCC 15.1
Unhandled attributes 100% 100% - 1st Jul 2024 15th Aug 2024 15th Aug 2024 GCC 15.1
Inline assembly 100% 100% - 1st Jun 2024 26th Aug 2024 15th Sep 2024 GCC 15.1
Rustc Testsuite Adaptor 100% 100% - 1st Jun 2024 26th Aug 2024 15th Sep 2024 GCC 15.1
Borrow checker improvements 100% 100% - 1st Jun 2024 26th Aug 2024 15th Sep 2024 GCC 15.1
Deref and DerefMut improvements 100% 100% - 28th Sep 2024 25th Oct 2024 28th Dec 2024 GCC 15.1
Indexing fixes 100% 100% - 21st Jul 2024 25th Dec 2024 15th Nov 2024 GCC 15.1
Iterator fixes 100% 100% - 21st Jul 2024 25th Dec 2024 15th Nov 2024 GCC 15.1
Auto traits improvements 100% 100% - 15th Sep 2024 20th Jan 2025 21st Dec 2024 GCC 15.1
Lang items 100% 100% - 1st Jul 2024 10th Jan 2025 21st Nov 2024 GCC 15.1
alloc parser issues 100% 100% - 7th Jan 2025 31st Jun 2024 28th Jan 2025 GCC 15.1
std parser issues 100% 100% - 7th Jan 2025 31st Jun 2024 28th Jan 2025 GCC 16.1
Question mark operator 100% 100% - 15th Dec 2024 21st Feb 2025 21st Feb 2025 GCC 15.1
Name resolution 2.0 rework 100% 100% - 1st Jun 2024 - 1st Apr 2025 GCC 15.1
Macro expansion 100% 100% - 1st Jun 2024 - 1st Jan 2025 GCC 15.1
Remaining typecheck issues 100% 100% - 21st Oct 2024 - 1st Mar 2025 GCC 15.1
cfg-core 100% 100% - 1st Dec 2024 24th Mar 2025 1st Mar 2025 GCC 15.1
Codegen fixes 100% 100% - 7th Oct 2024 1st Apr 2025 1st Mar 2025 GCC 15.1
blackbox intrinsic 100% 100% - 28th Oct 2024 - 28th Jan 2025 GCC 15.1
let-else 100% 100% - 28th Jan 2025 - 28th Feb 2025 GCC 15.1
Specialization 100% 100% - 1st Jan 2025 1st Apr 2025 1st Mar 2025 GCC 15.1
cfg-rfl 100% 100% - 7th Jan 2025 19th Mar 2025 15th Feb 2025 GCC 15.1
Downgrade to Rust 1.49 100% 100% - 14th Mar 2025 26th Mar 2025 1st Apr 2025 GCC 15.1
try blocks 100% 100% -   30th Jul 2025   GCC 16.1
while-let loops 100% 100% -   30th Jul 2025   GCC 16.1
offsetof!() builtin macro 100% 100% - 15th Mar 2025 4th Aug 2025 15th Aug 2025 GCC 16.1
Explicit generics with impl Trait 100% 100% - 28th Feb 2025 21st Jul 2025 28th Mar 2025 GCC 16.1
Final Inline assembly fixes 100% 100% -   -   GCC 16.1