"did you mean" should first try to find the name with different capitalization. A case I just found

error[E0531]: cannot find tuple struct/variant `TyUInt` in module `ty` --> src/librustc/infer/error_reporting/mod.rs:680:44 | 680 | (&ty::TyRef(_, ref tnm1), &ty::TyUInt(_)) | | ^^^^^^ did you mean `TyInt`? 

There's a ty::TyUint, which confused me for a few seconds until I noticed the i->I typo and the suggestion hindered instead of helping.