error[E0015]: `?` cannot determine the branch of `TryMe` in constant functions --> $DIR/const-try.rs:33:5 | LL | TryMe?; | ^^^^^^ | note: impl defined here, but it is not `const` --> $DIR/const-try.rs:21:1 | LL | impl const Try for TryMe { | ^^^^^^^^^^^^^^^^^^^^^^^^ = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants error[E0015]: `?` cannot convert from residual of `TryMe` in constant functions --> $DIR/const-try.rs:33:5 | LL | TryMe?; | ^^^^^^ | note: impl defined here, but it is not `const` --> $DIR/const-try.rs:15:1 | LL | impl const FromResidual for TryMe { | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0015`.