error[E0658]: function pointers cannot appear in constant functions
  --> $DIR/issue-37550.rs:3:9
   |
LL |     let x = || t;
   |         ^
   |
   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
   = help: add `#![feature(const_fn_fn_ptr_basics)]` to the crate attributes to enable

error: aborting due to previous error

For more information about this error, try `rustc --explain E0658`.