Move the untracked cstore and source_span into a struct

compiler/rustc_middle/src/query/mod.rs

@@ -43,6 +43,8 @@ rustc_queries! {
     /// This span is meant for dep-tracking rather than diagnostics. It should not be used outside
     /// of rustc_middle::hir::source_map.
     query source_span(key: LocalDefId) -> Span {
+        // Accesses untracked data
+        eval_always
         desc { "getting the source span" }
     }