Add failing test for codegen'd track_caller attribute.

Author: anp

src/test/ui/rfc-2091-track-caller/track-caller-attribute.rs

@@ -0,0 +1,40 @@
+// run-pass
+
+#![feature(const_fn, core_intrinsics, track_caller)]
+
+use std::{intrinsics::caller_location, panic::Location};
+
+#[track_caller]
+fn tracked() -> &'static Location <'static> {
+    caller_location()
+}
+
+fn nested_intrinsic() -> &'static Location<'static> {
+    caller_location()
+}
+
+fn nested_tracked() -> &'static Location<'static> {
+    tracked()
+}
+
+fn main() {
+    let location = caller_location();
+    assert_eq!(location.file(), file!());
+    assert_eq!(location.line(), 21);
+    assert_eq!(location.column(), 20);
+
+    let tracked = tracked();
+    assert_eq!(tracked.file(), file!());
+    assert_eq!(tracked.line(), 26);
+    assert_eq!(tracked.column(), 19);
+
+    let nested = nested_intrinsic();
+    assert_eq!(nested.file(), file!());
+    assert_eq!(nested.line(), 13);
+    assert_eq!(nested.column(), 5);
+
+    let contained = nested_tracked();
+    assert_eq!(contained.file(), file!());
+    assert_eq!(contained.line(), 17);
+    assert_eq!(contained.column(), 5);
+}

src/test/ui/rfc-2091-track-caller/track-caller-attribute.stderr

@@ -0,0 +1,8 @@
+warning: the feature `track_caller` is incomplete and may cause the compiler to crash
+  --> $DIR/track-caller-attribute.rs:3:39
+   |
+LL | #![feature(const_fn, core_intrinsics, track_caller)]
+   |                                       ^^^^^^^^^^^^
+   |
+   = note: `#[warn(incomplete_features)]` on by default
+