Exhaustively match on DefPathData in with_dummy_span

This will cause an error if we ever add/change variants of
`DefPathData`, as we need to ensure we strip spans from any `Ident`s

Author: Aaron1011

src/librustc/hir/map/definitions.rs

@@ -541,7 +541,7 @@ impl DefPathData {
             ValueNs(name) => ValueNs(Ident::with_dummy_span(name.name)),
             MacroNs(name) => MacroNs(Ident::with_dummy_span(name.name)),
             LifetimeNs(name) => LifetimeNs(Ident::with_dummy_span(name.name)),
-            _ => *self,
+            CrateRoot | Misc | Impl | ClosureExpr | Ctor | AnonConst | ImplTrait => *self,
         }
     }