Fix structured suggestion for explicit drop call

compiler/rustc_typeck/src/check/callee.rs

@@ -25,24 +25,24 @@ pub fn check_legal_trait_for_method_call(
     tcx: TyCtxt<'_>,
     span: Span,
     receiver: Option<Span>,
+    expr_span: Span,
     trait_id: DefId,
 ) {
     if tcx.lang_items().drop_trait() == Some(trait_id) {
         let mut err = struct_span_err!(tcx.sess, span, E0040, "explicit use of destructor method");
         err.span_label(span, "explicit destructor calls not allowed");
 
-        let snippet = receiver
+        let (sp, suggestion) = receiver
             .and_then(|s| tcx.sess.source_map().span_to_snippet(s).ok())
-            .unwrap_or_default();
-
-        let suggestion =
-            if snippet.is_empty() { "drop".to_string() } else { format!("drop({})", snippet) };
+            .filter(|snippet| !snippet.is_empty())
+            .map(|snippet| (expr_span, format!("drop({})", snippet)))
+            .unwrap_or_else(|| (span, "drop".to_string()));
 
         err.span_suggestion(
-            span,
-            &format!("consider using `drop` function: `{}`", suggestion),
-            String::new(),
-            Applicability::Unspecified,
+            sp,
+            "consider using `drop` function",
+            suggestion,
+            Applicability::MaybeIncorrect,
         );
 
         err.emit();

compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs

@@ -1163,7 +1163,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 debug!("instantiate_value_path: def_id={:?} container={:?}", def_id, container);
                 match container {
                     ty::TraitContainer(trait_did) => {
-                        callee::check_legal_trait_for_method_call(tcx, span, None, trait_did)
+                        callee::check_legal_trait_for_method_call(tcx, span, None, span, trait_did)
                     }
                     ty::ImplContainer(impl_def_id) => {
                         if segments.len() == 1 {

compiler/rustc_typeck/src/check/method/confirm.rs

@@ -507,6 +507,7 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
                 self.tcx,
                 self.span,
                 Some(self.self_expr.span),
+                self.call_expr.span,
                 trait_def_id,
             ),
             ty::ImplContainer(..) => {}