Lol no. The only thing this means is that type checking a Rust program might never terminate. Nothing more, nothing less. It might take 10 seconds, it might

Lol no. The only thing this means is that type checking a Rust program might never terminate. Nothing more, nothing less. It might take 10 seconds, it might take 10 days, it might take till the universe freezes. In practice, the compiler - like pretty much every single compiler with a Turing complete type system - has a recursion limit, that rejects programs that accidentally take too long to type check, but users can increase this limit by adding a source annotation (that's suggested by the compiler). This is completely orthogonal to whether the programs are valid or not. If your program is invalid, the compiler will never accept it, no matter how much compute time you throw at it. Type checking always terminates for valid Rust programs (by definition), so if you throw enough compute at any valid Rust program, the compiler will eventually accept it.