add indirect call example to track-caller-ffi.rs

Author: folkertdev

tests/ui/rfcs/rfc-2091-track-caller/track-caller-ffi.rs

@@ -2,14 +2,14 @@
 
 use std::panic::Location;
 
-extern "Rust" {
+unsafe extern "Rust" {
     #[track_caller]
-    fn rust_track_caller_ffi_test_tracked() -> &'static Location<'static>;
-    fn rust_track_caller_ffi_test_untracked() -> &'static Location<'static>;
+    safe fn rust_track_caller_ffi_test_tracked() -> &'static Location<'static>;
+    safe fn rust_track_caller_ffi_test_untracked() -> &'static Location<'static>;
 }
 
 fn rust_track_caller_ffi_test_nested_tracked() -> &'static Location<'static> {
-    unsafe { rust_track_caller_ffi_test_tracked() }
+    rust_track_caller_ffi_test_tracked()
 }
 
 mod provides {
@@ -31,18 +31,23 @@ fn main() {
     assert_eq!(location.line(), 29);
     assert_eq!(location.column(), 20);
 
-    let tracked = unsafe { rust_track_caller_ffi_test_tracked() };
+    let tracked = rust_track_caller_ffi_test_tracked();
     assert_eq!(tracked.file(), file!());
     assert_eq!(tracked.line(), 34);
-    assert_eq!(tracked.column(), 28);
+    assert_eq!(tracked.column(), 19);
 
-    let untracked = unsafe { rust_track_caller_ffi_test_untracked() };
+    let untracked = rust_track_caller_ffi_test_untracked();
     assert_eq!(untracked.file(), file!());
     assert_eq!(untracked.line(), 24);
     assert_eq!(untracked.column(), 9);
 
     let contained = rust_track_caller_ffi_test_nested_tracked();
     assert_eq!(contained.file(), file!());
     assert_eq!(contained.line(), 12);
-    assert_eq!(contained.column(), 14);
+    assert_eq!(contained.column(), 5);
+
+    let indirect = (rust_track_caller_ffi_test_tracked as fn() -> &'static Location<'static>)();
+    assert_eq!(indirect.file(), file!());
+    assert_eq!(indirect.line(), 7);
+    assert_eq!(indirect.column(), 5);
 }