1 files changed, 39 insertions, 0 deletions
diff --git a/src/test/ui/lub-glb/old-lub-glb-hr-noteq2.rs b/src/test/ui/lub-glb/old-lub-glb-hr-noteq2.rs
new file mode 100644
index 000000000..9940c40da
--- /dev/null
+++ b/src/test/ui/lub-glb/old-lub-glb-hr-noteq2.rs
@@ -0,0 +1,39 @@
+// Test taking the LUB of two function types that are not equatable but where
+// one is more general than the other. Test the case where the more general type
+// (`x`) is the second match arm specifically.
+//
+// FIXME(#73154) Pure NLL checker without leak check accepts this test.
+// (Note that it still errors in old-lub-glb-hr-noteq1.rs). What happens
+// is that, due to the ordering of the match arms, we pick the correct "more
+// general" fn type, and we ignore the errors from the non-NLL type checker that
+// requires equality. The NLL type checker only requires a subtyping
+// relationship, and that holds. To unblock landing NLL - and ensure that we can
+// choose to make this always in error in the future - we perform the leak check
+// after coercing a function pointer.
+
+// revisions: leak noleak
+//[noleak] compile-flags: -Zno-leak-check
+
+//[noleak] check-pass
+
+fn foo(x: for<'a, 'b> fn(&'a u8, &'b u8) -> &'a u8, y: for<'a> fn(&'a u8, &'a u8) -> &'a u8) {
+    // The two types above are not equivalent. With the older LUB/GLB
+    // algorithm, this may have worked (I don't remember), but now it
+    // doesn't because we require equality.
+    let z = match 22 {
+        0 => y,
+        _ => x,
+        //[leak]~^ ERROR `match` arms have incompatible types
+    };
+}
+
+fn foo_cast(x: for<'a, 'b> fn(&'a u8, &'b u8) -> &'a u8, y: for<'a> fn(&'a u8, &'a u8) -> &'a u8) {
+    // But we can *upcast* explicitly the type of `x` and figure
+    // things out:
+    let z = match 22 {
+        0 => x as for<'a> fn(&'a u8, &'a u8) -> &'a u8,
+        _ => y,
+    };
+}
+
+fn main() {}