Rollup merge of rust-lang#35296 - medzin:master, r=jonathandturner

Update error message E0178

Fixes rust-lang#35273 as part of rust-lang#35233.

src/librustc_typeck/astconv.rs

@@ -1088,6 +1088,7 @@ impl<'o, 'gcx: 'tcx, 'tcx> AstConv<'gcx, 'tcx>+'o {
                                                "expected a path on the left-hand side \
                                                 of `+`, not `{}`",
                                                pprust::ty_to_string(ty));
+                err.span_label(ty.span, &format!("expected a path"));
                 let hi = bounds.iter().map(|x| match *x {
                     hir::TraitTyParamBound(ref tr, _) => tr.span.hi,
                     hir::RegionTyParamBound(ref r) => r.span.hi,

src/test/compile-fail/E0178.rs

@@ -11,10 +11,18 @@
 trait Foo {}
 
 struct Bar<'a> {
-    w: &'a Foo + Copy, //~ ERROR E0178
-    x: &'a Foo + 'a, //~ ERROR E0178
-    y: &'a mut Foo + 'a, //~ ERROR E0178
-    z: fn() -> Foo + 'a, //~ ERROR E0178
+    w: &'a Foo + Copy,
+    //~^ ERROR E0178
+    //~| NOTE expected a path
+    x: &'a Foo + 'a,
+    //~^ ERROR E0178
+    //~| NOTE expected a path
+    y: &'a mut Foo + 'a,
+    //~^ ERROR E0178
+    //~| NOTE expected a path
+    z: fn() -> Foo + 'a,
+    //~^ ERROR E0178
+    //~| NOTE expected a path
 }
 
 fn main() {