June 2024 Monthly report

Overview

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

Project update

All of our GSoC students are progressing nicely on their projects. Jasmine Tang has worked her inline assembly nodes through almost all of the passes of our pipeline, and is now working on lowering them to GCC’s inline assembly representation. The rustc testsuite adapter tool, whose development is lead by Muhammad Mahad, is starting to be usable for converting rusttest testcases to the dejagnu format, and we are expecting the integration of some rustc testcases to our testsuite shortly. Finally, Kushal Pal’s error reporting for borrow-checking errors is moving along nicely - we are currently dealing with transmitting data between the Rust polonius engine and our C++ compiler, which is a complex task with lots of edge cases.

The milestones for GCC 14.2 and 15.1 are completed, and we are now waiting on reviews for the patches sent upstream. We are hoping to get our documentation-related patches merged in time for 14.2, and will get in touch with the release managers to address this matter. In other technical news, we have started working on the milestones related to for loops handling and are making good progress. Work continues on the name resolution rework, which we aim to complete in order to handle core 1.49 properly.

Finally, gccrs will be attending two international Rust conferences this year, with Arthur being present at RustConf and Pierre-Emmanuel attending EuroRust. We are looking forward to meeting with the community once again, and to talk about compilers for way too long :)

Community call

We will have our next monthly community call on the 8th of July at 9am 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.

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

Call for contribution

• Issue 3001: Generic arguments are not disambiguated on error propagation expressions

Our error propagation expressions (expressions which use the question mark operator, of the form <expr>?) are currently forgotten in many of our AST visitors. As a result, there are unexpected cases when it comes to various parts of the compiler pipeline handling them. In that particular case, the function call’s generic arguments are not disambiguated - the compiler does not know if it needs to be handling a generic type, or a const generic value. You will need to add handling to our name resolution pass for these error propagation expressions. It would be helpful to look at the current generic disambiguation to start figuring out where it is called from, and where you need to call it.

• Issue 3045: Prevent #[may_dangle] attribute from being used in safe impl

The #[may_dangle] attribute is an important part of core 1.49, as it is used in many Drop implementations of complex Rust standard types. However, the usage of this attribute is complex, and has certain consequences on the borrow-checker and drop-checker, two integral parts of the Rust compiler pipeline. Because of this, its use is restricted to unsafe trait implementations, which is a behavior we aim to reproduce in gccrs. Have a look at our UnsafeChecker compiler pass to see what you will need to modify. You can read about the #[may_dangle] attribute here.

Completed Activities

• Store parse result of parse_formatstring(s) PR3073
• Add RAW_{STRINGLITERAL} PR3065
• Added ExprType::InlineAsm PR3063
• Add test case for using asm! outside of unsafe {} PR3059
• Emit error on optional supertraits PR3055
• expand: Keep track of semicoloned builtin macros PR3054
• incorporate tl::expected into InlineAsm parsing PR3053
• Parse exclusive range pattern PR3025
• Parse raw borrow PR3020
• Add outer attributes to struct expr fields PR3017
• Fix outer attribute parsing on generic parameters PR3014
• Parse box keyword PR3012
• Inline asm PR2982
• Do not link -ldl and -lpthread unconditionally PR2949
• Improve handling of ```ConstantItem``` during name resolution 2.0 PR2900

Contributors this month

• AnshVM (new contributor!)
• Jasmine Tang
• Owen Avery
• Pierre-Emmanuel Patry
• Arthur Cohen

Overall Task Status

Test Cases

Bugs

Milestones Progress

For the GCC 14.2 milestone, the work has been completed and submitted upstream - we are just waiting on reviews and on approval for merging into the 14.2 branch.

Planned Activities

• Start work on required items for for loops
• Continue work on name resolution and macro expansion for core 1.49
• Be proactive about 14.2 reviews
• Start adding Detailed Changelogs to the reports again

Risks

There have been no changes to the Risk table this month

Detailed changelog