I could imagine two tools: 1. A tool that parses the text and draws red underlines on all the errors, this exists but (at least for C++ in VS 2017) it is quite slow. 2. A tool that automatically populates and updates types of variables and functions.

Both of these could be achieved by somehow decoupling the front-end (as in before semantic analysis) of compilers and making them output the AST in some standardized tree-structured format like XML.