GCC Rust Status Monthly Report #1 – December 2020

Since November 23rd the feedback from rustc compiler developers bjorn3 and Philipp Krones have been crucial in designing a proper architecture for the compiler moving forward. The code was not going to be able to handle to declare first, generics and traits uniformly. This first month a new HIR IR has been added with a node ID mapping system akin to rustc which allows implementation of the Hindley Milner type inferencing algorithm, which requires all nodes to be unified with rules to determine types.

Consider declare first case we must examine all usages of the name x:

let x; // inference variable _
x = 1; // i32

Using type resolution rules it is possible to implement the following case.

let mut x; // _
x = None; // option<_>
x = 1; // option<i>32

As part of this large re-architecture a new name and type resolver are in place which have been designed with thought towards generics and traits down the line. GCCRS is still on track to complete the Core Data structure milestone.

Special thanks to SimplyTheOther for his parser bug fixes this month. When this project was resurrected earlier in 2020 we joined forces by taking his new parser since the existing parser targeted rust 0.8.

For this year of funding I believe the best usage of my time is to get onto implementing generics and traits where the most complexity and unknowns lie for the compiler.

Completed Activities

Overall Task Status

Category	Last Month	This Month	Delta
ToDo	25	35	+10
In Progress	4	5	+1
Completed	6	23	+17

Testsuite status

Test Cases	Last Month	This Month	Delta
Passing	40	124	+84
Failing	4	8	+4

Milestones Progress

Milestone	Last Month	This Month	Delta
Core Data Structures	38%	61%	+23%
Basic Control Flow	0%	14%	+14%
Generics	0%	0%	0%
Traits	0%	0%	0%
Pattern Matching	0%	0%	0%
Imports	0%	0%	0%

Risks

Risk	Impact (1-3)	Likelihood (1-10)	Risk (I * L)	Mitigation
Copyright assignments	2	5	10	Be up front on all PRs that the code is destined to be upstreamed to FSF

Planned Activities