src/test/ui/closures/closure-bounds-cant-promote-superkind-in-struct.stderr

error[E0277]: `F` cannot be sent between threads safely
  --> $DIR/closure-bounds-cant-promote-superkind-in-struct.rs:5:1
   |
LL |   struct X<F> where F: FnOnce() + 'static + Send {
   |   ---------------------------------------------- required by `X`
...
LL |   fn foo<F>(blk: F) -> X<F> where F: FnOnce() + 'static {
   |   ^                                                    - help: consider further restricting type parameter `F`: `, F: std::marker::Send`
   |  _|
   | |
LL | |
LL | |     return X { field: blk };
LL | | }
   | |_^ `F` cannot be sent between threads safely
   |
   = help: the trait `std::marker::Send` is not implemented for `F`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0277`.