Add test for Location::caller in a macro.

src/test/ui/rfc-2091-track-caller/intrinsic-wrapper.rs

@@ -0,0 +1,21 @@
+// run-pass
+
+#![feature(track_caller)]
+
+macro_rules! caller_location_from_macro {
+    () => (core::panic::Location::caller());
+}
+
+fn main() {
+    let loc = core::panic::Location::caller();
+    assert_eq!(loc.file(), file!());
+    assert_eq!(loc.line(), 10);
+    assert_eq!(loc.column(), 15);
+
+    // `Location::caller()` in a macro should behave similarly to `file!` and `line!`,
+    // i.e. point to where the macro was invoked, instead of the macro itself.
+    let loc2 = caller_location_from_macro!();
+    assert_eq!(loc2.file(), file!());
+    assert_eq!(loc2.line(), 17);
+    assert_eq!(loc2.column(), 16);
+}