About the Project

Welcome to the final work product submission for my Google Summer of Code project.

This book serves as the comprehensive final report and technical documentation for my work on the gccrs compiler (the Rust front-end for GCC).

Below is a summary of the project. For in-depth technical details, methodologies, and code architecture, please navigate through the chapters using the sidebar.

What Were the Project Goals?

The primary goal of this project was to implement the compiler infrastructure required to compile Rust’s alloc crate natively within gccrs. This involved identifying, designing, and implementing missing lang items, compiler intrinsics, built-in attributes, and complex architectural features (like DSTs, Fat Pointers, and Unsized Coercions). For the underlying reasoning, refer to Why Compile the ‘alloc’ Crate?.

What Was Accomplished?

I addressed all the missing pieces required by the alloc crate. During development, my primary priority was always a full, end-to-end implementation.

In cases where a full implementation was strictly blocked by upstream compiler limitations, features were safely registered as stubs. Every stub was a deliberate, well-considered decision made to unblock standard library parsing without introducing unsound behavior. Detailed breakdowns can be found in What Has Been Done? and the complete list of PRs in Contributions.

What is the Current State?

The architectural groundwork for alloc is firmly in place. Currently, we can successfully compile the alloc crate up to the name resolution phase using a custom mock core module. Every individual feature and intrinsic implemented during this project is fully functional and covered by isolated regression tests in the gccrs test suite. This architecture is detailed in Current State & Mock Core Architecture.

What is Left to Do?

From a strictly alloc-specific perspective, the fundamental infrastructure is complete. The remaining work involves routine maintenance on the newly merged patches. The ultimate goal—compiling alloc end-to-end—is currently bottlenecked by the ongoing development of the upstream core crate support. As the gccrs mature, the temporary stubs we established will be cleanly replaced with their final backend implementations. For future projections, see Roadmap & Next Steps.

Note

To Reproduce the Work: If you wish to build the compiler and test these changes locally, I have created a fully reproducible Nix flake environment. View Setup Instructions