While Tree-sitter is heavily influenced by Wagner's thesis, our error recovery strategy actually uses a novel approach, so it is fair to question whether Wagner's would have different properties.

For error recovery, Tree-sitter is currently optimized for some goals that are a bit different from the goals of a single-language IDE like Rust-Analyzer:

  * Like RA, we want to minimize the impact of syntax errors on basic features like syntax highlighting and symbol name extraction (which are important to GitHub, and in lightweight text editors like Neovim and Atom).
  * Unlike RA, I wanted to avoid requiring grammar authors to think about error recovery at all. 
  * We needed to tightly control the performance cost of pathological error recovery cases, like parsing a large Ruby file as Go (either accidentally or adversarially).

My understanding is that Wagner's thesis is mostly concerned with "history-sensitive" error recovery in an IDE: using earlier syntax trees as an additional input to the error recovery process in order to better understand the user's intent when editing.

I think this idea makes a lot of sense, but it doesn't address cases like Matklad has prevented here, where the IDE is presented with already-invalid file.