src/test/ui/lub-glb/old-lub-glb-hr-noteq1.rs

   1 // Test taking the LUB of two function types that are not equatable but where one is more
   2 // general than the other. Test the case where the more general type (`x`) is the first
   3 // match arm specifically.
   4
   5 fn foo(x: for<'a, 'b> fn(&'a u8, &'b u8) -> &'a u8, y: for<'a> fn(&'a u8, &'a u8) -> &'a u8) {
   6     // The two types above are not equivalent. With the older LUB/GLB
   7     // algorithm, this may have worked (I don't remember), but now it
   8     // doesn't because we require equality.
   9     let z = match 22 {
  10         0 => x,
  11         _ => y, //~ ERROR `match` arms have incompatible types
  12     };
  13 }
  14
  15 fn foo_cast(x: for<'a, 'b> fn(&'a u8, &'b u8) -> &'a u8, y: for<'a> fn(&'a u8, &'a u8) -> &'a u8) {
  16     // But we can *upcast* explicitly the type of `x` and figure
  17     // things out:
  18     let z = match 22 {
  19         0 => x as for<'a> fn(&'a u8, &'a u8) -> &'a u8,
  20         _ => y,
  21     };
  22 }
  23
  24 fn main() {}