Use last path segment for uncalled method note if span_to_segment fails

PR: #32053

Author: Daniel J Rollins

src/librustc_typeck/check/method/suggest.rs

@@ -25,11 +25,13 @@ use middle::subst::Substs;
 use middle::traits::{Obligation, SelectionContext};
 use util::nodemap::{FnvHashSet};
 
+
 use syntax::ast;
 use syntax::codemap::Span;
 use syntax::errors::DiagnosticBuilder;
 use rustc_front::print::pprust;
 use rustc_front::hir;
+use rustc_front::hir::Expr_;
 
 use std::cell;
 use std::cmp::Ordering;
@@ -130,17 +132,28 @@ pub fn report_error<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
             }
 
             if is_fn_ty(&rcvr_ty, &fcx, span) {
-                if let Some(expr) = rcvr_expr {
-                    if let Ok (expr_string) = cx.sess.codemap().span_to_snippet(expr.span) {
+                macro_rules! report_function {
+                    ($span:expr, $name:expr) => {
                         err.fileline_note(
-                            expr.span,
+                            $span,
                             &format!("{} is a function, perhaps you wish to call it",
-                                     expr_string));
+                                     $name));
+                    }
+                }
+
+                if let Some(expr) = rcvr_expr {
+                    if let Ok (expr_string) = cx.sess.codemap().span_to_snippet(expr.span) {
+                        report_function!(expr.span, expr_string);
                         err.span_suggestion(expr.span,
                                             "try calling the base function:",
                                             format!("{}()",
                                                     expr_string));
                     }
+                    else if let Expr_::ExprPath(_, path) = expr.node.clone() {
+                        if let Some(segment) = path.segments.last() {
+                            report_function!(expr.span, segment.identifier.name);
+                        }
+                    }
                 }
             }
 

src/test/compile-fail/issue-29124.rs

@@ -22,10 +22,10 @@ fn func() -> ret {
 }
 
 fn main() {
-    obj::func.x(); 
+    obj::func.x();
     //~^ ERROR no method named `x` found for type `fn() -> ret {obj::func}` in the current scope
     //~^^ NOTE obj::func is a function, perhaps you wish to call it
-    func.x(); 
+    func.x();
     //~^ ERROR no method named `x` found for type `fn() -> ret {func}` in the current scope
     //~^^ NOTE func is a function, perhaps you wish to call it
 }