Updates compiler error E0040 with new format

src/librustc_typeck/check/callee.rs

@@ -28,7 +28,9 @@ use rustc::hir;
 /// method that is called)
 pub fn check_legal_trait_for_method_call(ccx: &CrateCtxt, span: Span, trait_id: DefId) {
     if ccx.tcx.lang_items.drop_trait() == Some(trait_id) {
-        span_err!(ccx.tcx.sess, span, E0040, "explicit use of destructor method");
+        struct_span_err!(ccx.tcx.sess, span, E0040, "explicit use of destructor method")
+            .span_label(span, &format!("call to destructor method"))
+            .emit();
     }
 }
 

src/test/compile-fail/E0040.rs

@@ -20,5 +20,7 @@ impl Drop for Foo {
 
 fn main() {
     let mut x = Foo { x: -7 };
-    x.drop(); //~ ERROR E0040
+    x.drop();
+    //~^ ERROR E0040
+    //~| NOTE call to destructor method
 }