error[E0015]: cannot perform deref coercion on `A` in statics
  --> $DIR/issue-25901.rs:4:24
   |
LL | static S: &'static B = &A;
   |                        ^^
   |
   = note: attempting to deref into `B`
note: deref defined here
  --> $DIR/issue-25901.rs:10:5
   |
LL |     type Target = B;
   |     ^^^^^^^^^^^
note: impl defined here, but it is not `const`
  --> $DIR/issue-25901.rs:9:1
   |
LL | impl Deref for A {
   | ^^^^^^^^^^^^^^^^
   = note: calls in statics are limited to constant functions, tuple structs and tuple variants
   = help: add `#![feature(const_trait_impl)]` to the crate attributes to enable
   = note: consider wrapping this expression in `Lazy::new(|| ...)` from the `once_cell` crate: https://crates.io/crates/once_cell

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0015`.