Finish fixing rust-lang#30159. This reverts PR rust-lang#30294.

Author: jseyfried

src/librustc_resolve/resolve_imports.rs

@@ -923,9 +923,6 @@ impl<'a, 'b:'a, 'tcx:'b> ImportResolver<'a, 'b, 'tcx> {
                             is_public: is_public
                         };
                     }
-                } else {
-                    // FIXME #30159: This is required for backwards compatability.
-                    dest_import_resolution[namespace].is_public |= is_public;
                 }
             };
             merge_child_item(ValueNS);

src/test/compile-fail/shadowed-use-visibility.rs

@@ -17,6 +17,10 @@ mod foo {
 
 mod bar {
     use foo::bar::f as g; //~ ERROR unresolved import
+
+    use foo as f;
+    pub use foo::*;
 }
 
+use bar::f::f; //~ ERROR unresolved import
 fn main() {}