src/test/mir-opt/issue_41697.rs

   1 // Regression test for #41697. Using dump-mir was triggering
   2 // artificial cycles: during type-checking, we had to get the MIR for
   3 // the constant expressions in `[u8; 2]`, which in turn would trigger
   4 // an attempt to get the def-path, which in turn would request the
   5 // types of the impl, which would trigger a cycle. We suppressed this
   6 // cycle now by forcing mir-dump to avoid asking for types of an impl.
   7
   8 #![feature(rustc_attrs)]
   9
  10 use std::sync::Arc;
  11
  12 trait Foo {
  13     fn get(&self) -> [u8; 2];
  14 }
  15
  16
  17 // EMIT_MIR issue_41697.{impl#0}-{constant#0}.SimplifyCfg-promote-consts.after.mir
  18 impl Foo for [u8; 1+1] {
  19     fn get(&self) -> [u8; 2] {
  20         *self
  21     }
  22 }
  23
  24 struct Bar<T: ?Sized>(T);
  25
  26 fn unsize_fat_ptr<'a>(x: &'a Bar<Foo + Send + 'a>) -> &'a Bar<Foo + 'a> {
  27     x
  28 }
  29
  30 fn unsize_nested_fat_ptr(x: Arc<Foo + Send>) -> Arc<Foo> {
  31     x
  32 }
  33
  34 fn main() {
  35     let x: Box<Bar<Foo + Send>> = Box::new(Bar([1,2]));
  36     assert_eq!(unsize_fat_ptr(&*x).0.get(), [1, 2]);
  37
  38     let x: Arc<Foo + Send> = Arc::new([3, 4]);
  39     assert_eq!(unsize_nested_fat_ptr(x).get(), [3, 4]);
  40 }