mem-cache: Assert Entry inherits from QueueEntry in Queue

Queue has several assumptions regarding its template parameter,
so make sure they are fulfilled by forcing Entry to be derived
from QueueEntry.

Change-Id: I0203a62aec00c04ac89e9674d86a44a07f9f13ab
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/17529
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>

src/mem/cache/queue.hh

@@ -51,6 +51,7 @@
 
 #include <cassert>
 #include <string>
+#include <type_traits>
 
 #include "base/logging.hh"
 #include "base/trace.hh"
@@ -68,6 +69,9 @@
 template<class Entry>
 class Queue : public Drainable
 {
+    static_assert(std::is_base_of<QueueEntry, Entry>::value,
+        "Entry must be derived from QueueEntry");
+
   protected:
     /** Local label (for functional print requests) */
     const std::string label;