Resolve infered types when complaining about unexpected call type

Author: estebank

compiler/rustc_typeck/src/check/callee.rs

@@ -350,6 +350,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     }
                 }
 
+                let callee_ty = self.resolve_vars_if_possible(callee_ty);
                 let mut err = type_error_struct!(
                     self.tcx.sess,
                     callee_expr.span,

src/test/ui/typeck/call-block.rs

@@ -1,3 +1,3 @@
 fn main() {
-    let _ = {42}(); //~ ERROR expected function, found `_`
+    let _ = {42}(); //~ ERROR expected function, found `{integer}`
 }

src/test/ui/typeck/call-block.stderr

@@ -1,4 +1,4 @@
-error[E0618]: expected function, found `_`
+error[E0618]: expected function, found `{integer}`
   --> $DIR/call-block.rs:2:13
    |
 LL |     let _ = {42}();