Fixed note message to display expression in recommendations

Author: Nashenas88

src/librustc_typeck/check/method/suggest.rs

@@ -59,22 +59,35 @@ pub fn report_error<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
                 None);
 
             // If the item has the name of a field, give a help note
-            if let (&ty::TyStruct(did, substs), Some(_)) = (&rcvr_ty.sty, rcvr_expr) {
+            if let (&ty::TyStruct(did, substs), Some(expr)) = (&rcvr_ty.sty, rcvr_expr) {
                 let fields = ty::lookup_struct_fields(cx, did);
 
                 if let Some(field) = fields.iter().find(|f| f.name == item_name) {
+                    let expr_string = match cx.sess.codemap().span_to_snippet(expr.span) {
+                        Ok(expr_string) => expr_string,
+                        _ => "s".into() // default to generic placeholder for expression
+                    };
 
+                    // TODO Fix when closure note is displayed
+                    // below commented code from eddyb on irc
+                    // let substs = subst::Substs::new_trait(vec![fcx.inh.infcx.next_ty_var()], Vec::new(), field_ty);
+                    // let trait_ref = ty::TraitRef::new(trait_def_id, fcx.tcx().mk_substs(substs));
+                    // let poly_trait_ref = trait_ref.to_poly_trait_ref();
+                    // let obligation = traits::Obligation::misc(span, fcx.body_id, poly_trait_ref.as_predicate());
+                    // let mut selcx = traits::SelectionContext::new(fcx.infcx(), fcx);
+                    // if selcx.evaluate_obligation(&obligation) { /* suggest */ }
+                    
                     match ty::lookup_field_type(cx, did, field.id, substs).sty {
                         ty::TyClosure(_, _) | ty::TyBareFn(_,_) => {
                             cx.sess.span_note(span,
                                 &format!("use `({0}.{1})(...)` if you meant to call the \
                                           function stored in the `{1}` field",
-                                    ty::item_path_str(cx, did), item_name));
+                                    expr_string, item_name));
                         },
                         _ => {
                             cx.sess.span_note(span,
                                 &format!("did you mean to write `{0}.{1}`?",
-                                    ty::item_path_str(cx, did), item_name));
+                                    expr_string, item_name));
                         },
                     };
                 }

src/test/compile-fail/issue-18343.rs

@@ -13,18 +13,30 @@ struct Obj<F> where F: FnMut() -> u32 {
     nfn: usize,
 }
 
+struct S<F> where F: FnMut() -> u32 {
+    v: Obj<F>,
+}
+
 fn func() -> u32 {
     0
 }
 
 fn main() {
-    let o = Obj { closure: || 42 };
+    let o = Obj { closure: || 42, nfn: 42 };
     o.closure(); //~ ERROR no method named `closure` found
-    //~^ NOTE use `(s.closure)(...)` if you meant to call the function stored in the `closure` field
-    let x = o.nfn(); //~ ERROR no method named `closure` found
-    //~^ NOTE did you mean `o.nfn`?
+    //~^ NOTE use `(o.closure)(...)` if you meant to call the function stored in the `closure` field
 
-    let b = Obj { closure: func };
+    // TODO move these to a new test for #2392
+    let x = o.nfn(); //~ ERROR no method named `nfn` found
+    //~^ NOTE did you mean to write `o.nfn`?
+
+    let b = Obj { closure: func, nfn: 5 };
     b.closure(); //~ ERROR no method named `closure` found
-    //~^ NOTE use `(s.closure)(...)` if you meant to call the function stored in the `closure` field
+    //~^ NOTE use `(b.closure)(...)` if you meant to call the function stored in the `closure` field
+
+    let s = S { v: b };
+    s.v.closure();//~ ERROR no method named `closure` found
+    //~^ NOTE use `(s.v.closure)(...)` if you meant to call the function stored in the `closure` field
+    s.v.nfn();//~ ERROR no method named `nfn` found
+    //~^ NOTE did you mean to write `s.v.nfn`?
 }