You can do stuff that's quite a bit more amazing than that (though I guess this goes against his point of "manage expectations"):
For any given C++ refactoring (rename method + swap args), propagate that refactoring automatically to every caller of the refactored function, such that upgrading to a new version of the library is automatically refactored correctly.
Parse this Python function and emit it as C, for optimization. Parse this C function and emit it as Python, for readability.
Cross-layer data-flow analysis - so you could track that a lock that's taken out in Java and released in C++ code would never produce deadlocks.
For any given C++ refactoring (rename method + swap args), propagate that refactoring automatically to every caller of the refactored function, such that upgrading to a new version of the library is automatically refactored correctly.
Parse this Python function and emit it as C, for optimization. Parse this C function and emit it as Python, for readability.
Cross-layer data-flow analysis - so you could track that a lock that's taken out in Java and released in C++ code would never produce deadlocks.