Clang Error Index: A Searchable Platform for Exploring Clang Diagnostics (original) (raw)

Hi everyone,

@jdoerfert and I would like to share a tool we’ve been working on: the Clang Error Index — a searchable platform intended to make it easier to navigate, understand, and reproduce Clang’s diagnostics. It draws inspiration from resources like Rust Error Code Index, aiming to provide a lightweight, developer-oriented reference for Clang error messages.

Motivation

As Clang continues to grow alongside evolving C/C++ standards, its diagnostic system has become richer but also more complex.
While Clang’s error and warning messages are a critical part of developer experience, they are often dispersed across codebases and not always easy to trace or reproduce.
The Clang Index is an effort to make this information more accessible by offering a centralized, searchable view into Clang’s diagnostics.

Data Collection: Powered by Fuzzlang

The Clang Index is built on top of datasets collected through our separate project, Fuzzlang — a framework designed to systematically generate and reproduce compiler errors.

In brief, Fuzzlang:

• Uses a Transformer to create diverse compilation errors from real-world code.
• Deploys an LLM-based Agent to isolate and validate diagnostics from internal compiler tests.

(We plan to release the full Fuzzlang paper and codebase soon.)

Future Directions

While assembling the Clang Index, we observed that a substantial number of diagnostics are not yet covered by test cases in the Clang repository.
We hope this platform can also assist the community by:

• Highlighting diagnostics that could benefit from additional test coverage.
• Identifying diagnostics that may no longer be reachable or relevant.

We welcome contributions, suggestions, or discussions on how the Index can better serve the LLVM community.

Current Status and Call for Collaboration

The Clang Index is still in its early stages of development.
We are actively working to reproduce more diagnostic examples and expand the coverage.
We also plan to gradually enhance the functionality and user experience of the website over time.

Once the project is open-sourced, we would warmly welcome contributions — particularly from those with frontend development expertise — who are interested in helping us improve and extend the platform further.

In the meantime, we invite you to explore the Clang Index, and we appreciate any feedback, suggestions, or bug reports!

Thanks for reading!