src/test/ui/polymorphization/closure_in_upvar/fnmut.rs

   1 // build-pass
   2 // compile-flags:-Zpolymorphize=on -Csymbol-mangling-version=v0
   3
   4 fn foo(f: impl Fn()) {
   5     // Mutate an upvar from `x` so that it implements `FnMut`.
   6     let mut outer = 3;
   7     let mut x = |_: ()| {
   8         outer = 4;
   9         ()
  10     };
  11
  12     // Don't use `f` in `y`, but refer to `x` so that the closure substs contain a reference to
  13     // `x` that will differ for each instantiation despite polymorphisation of the varying
  14     // argument.
  15     let mut y = || x(());
  16
  17     // Consider `f` used in `foo`.
  18     f();
  19     // Use `y` so that it is visited in monomorphisation collection.
  20     y();
  21 }
  22
  23 fn entry_a() {
  24     foo(|| ());
  25 }
  26
  27 fn entry_b() {
  28     foo(|| ());
  29 }
  30
  31 fn main() {
  32     entry_a();
  33     entry_b();
  34 }