Add a test for mismatch in #[track_caller] wrt tail calls

Author: WaffleLapkin

tests/ui/explicit-tail-calls/caller-location-mismatch.rs

@@ -0,0 +1,28 @@
+#![feature(explicit_tail_calls)]
+use std::panic::Location;
+
+fn get_some_location1() -> &'static Location<'static> {
+    #[track_caller]
+    fn inner() -> &'static Location<'static> {
+        become Location::caller()
+    }
+
+    become inner()
+    //~^ error: a function mot marked with `#[track_caller]` cannot tail-call one that is
+}
+
+#[track_caller]
+fn get_some_location2() -> &'static Location<'static> {
+    fn inner() -> &'static Location<'static> {
+        become Location::caller()
+        //~^ error: a function mot marked with `#[track_caller]` cannot tail-call one that is
+    }
+
+    become inner()
+    //~^ error: a function marked with `#[track_caller]` cannot tail-call one that is not
+}
+
+fn main() {
+    get_some_location1();
+    get_some_location2();
+}

tests/ui/explicit-tail-calls/caller-location-mismatch.stderr

@@ -0,0 +1,20 @@
+error: a function mot marked with `#[track_caller]` cannot tail-call one that is
+  --> $DIR/caller-location-mismatch.rs:10:5
+   |
+LL |     become inner()
+   |     ^^^^^^^^^^^^^^
+
+error: a function marked with `#[track_caller]` cannot tail-call one that is not
+  --> $DIR/caller-location-mismatch.rs:21:5
+   |
+LL |     become inner()
+   |     ^^^^^^^^^^^^^^
+
+error: a function mot marked with `#[track_caller]` cannot tail-call one that is
+  --> $DIR/caller-location-mismatch.rs:17:9
+   |
+LL |         become Location::caller()
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 3 previous errors
+