Functions inlined into reachable functions are reachable

Consider functions to be reachable for code coverage purposes, either
when they reach the code generation directly, or indirectly as inlined
part of another function.

compiler/rustc_middle/src/query/mod.rs

@@ -1397,6 +1397,14 @@ rustc_queries! {
     query is_codegened_item(def_id: DefId) -> bool {
         desc { |tcx| "determining whether `{}` needs codegen", tcx.def_path_str(def_id) }
     }
+
+    /// All items participating in code generation together with items inlined into them.
+    query codegened_and_inlined_items(_: CrateNum)
+        -> &'tcx DefIdSet {
+        eval_always
+       desc { "codegened_and_inlined_items" }
+    }
+
     query codegen_unit(_: Symbol) -> &'tcx CodegenUnit<'tcx> {
         desc { "codegen_unit" }
     }