Oops, Cubic Macro
Summary
The post analyzes Rust macro expansion in rust-analyzer versus rustc, focusing on how macros are parsed, potential parsing strategies (DFS vs BFS vs packrat), and the impact of repetitions on ambiguity and performance. It proposes a linear-time, memoized parsing approach to detect ambiguity and outlines a proof-of-concept with runtime measurements up to 41 tokens, indicating significant time and memory growth and a path toward potential optimization.