I Fuzzed, and Vibe Fixed, the Vibed C Compiler
Summary
John Regehr analyzes Claude's C Compiler (CCC) using fuzz testing with Csmith and YARPGen, showing miscompilations and how Codex patched 11 bugs to render CCC robust to a large test suite. He notes that while CCC is impressive in scope, it is not production-grade like GCC/LLVM and that most defects in production compilers lie in optimizers. The piece discusses the usefulness and limits of AI assistants (Codex) in fixing bugs with minimal guidance, and provides a list of commits illustrating practical AI-assisted patching and regression testing in action.