src/test/ui/type-alias-impl-trait/wf-check-fn-ptrs.rs

   1 #![feature(type_alias_impl_trait)]
   2
   3 // build-pass
   4
   5 trait Bar {
   6     fn bar(&self);
   7 }
   8
   9 type FooFn<B> = impl FnOnce(B);
  10
  11 fn foo<B: Bar>() -> FooFn<B> {
  12     fn mop<B: Bar>(bar: B) { bar.bar() }
  13     mop as fn(B)
  14     // function pointers don't have any obligations on them,
  15     // thus the above compiles. It's obviously unsound to just
  16     // procure a `FooFn` from the ether without making sure that
  17     // the pointer is actually legal for all `B`
  18 }
  19
  20 fn main() {
  21     let boom: FooFn<u32> = unsafe { core::mem::zeroed() };
  22     boom(42);
  23 }