lint to use self for this/my

Author: csmoe

src/librustc_resolve/lib.rs

@@ -2981,13 +2981,13 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
             // Make the base error.
             let expected = source.descr_expected();
             let path_str = names_to_string(path);
+            let item_str = path[path.len() - 1];
             let code = source.error_code(def.is_some());
             let (base_msg, fallback_label, base_span) = if let Some(def) = def {
                 (format!("expected {}, found {} `{}`", expected, def.kind_name(), path_str),
                  format!("not a {}", expected),
                  span)
             } else {
-                let item_str = path[path.len() - 1];
                 let item_span = path[path.len() - 1].span;
                 let (mod_prefix, mod_str) = if path.len() == 1 {
                     (String::new(), "this scope".to_string())
@@ -3010,6 +3010,20 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
             let code = DiagnosticId::Error(code.into());
             let mut err = this.session.struct_span_err_with_code(base_span, &base_msg, code);
 
+            // Emit help message for fake-self from other languages like `this`(javascript)
+            let fake_self: Vec<Ident> = ["this", "my"].iter().map(
+                |s| Ident::from_str(*s)
+            ).collect();
+            if fake_self.contains(&item_str)
+                && this.self_value_is_available(path[0].span, span) {
+                err.span_suggestion_with_applicability(
+                    span,
+                    "did you mean",
+                    "self".to_string(),
+                    Applicability::MachineApplicable,
+                );
+            }
+
             // Emit special messages for unresolved `Self` and `self`.
             if is_self_type(path, ns) {
                 __diagnostic_used!(E0411);