I wouldn’t expect someone to replicate a full compiler as an internal editor plugin ever again only to highlight mistakes. Language servers and their support is

I wouldn’t expect someone to replicate a full compiler as an internal editor plugin ever again only to highlight mistakes. Language servers and their support is one of the best things that happened to editors recently. Everyone moved on from ad-hoc plugins. LSP is what you’re looking for, imo. A regular LSP for semantic errors and a linter LSP[-like] for style, bad practice, unused entity, deprecation, etc warnings. For requirement 2 and 3 I think VSCode can do that. Some themes tint every possible class of token, so casting will look different from multiplication. Afaik, it definitely differentiates functions, locals, globals and members, while they are all identifiers.