Completely remove cpp_typecheckt::check_template_restrictions

It was unused and disabled via #if 0; resurrect via git if needed.

Author: tautschnig

src/cpp/cpp_typecheck.h

@@ -136,13 +136,6 @@ class cpp_typecheckt:public c_typecheck_baset
     const template_typet &old_type,
     template_typet &new_type);
 
-  #if 0
-  void check_template_restrictions(
-    const irept &cpp_name,
-    const irep_idt &final_identifier,
-    const typet &final_type);
-  #endif
-
   void convert_template_declaration(cpp_declarationt &declaration);
 
   void convert_non_template_declaration(cpp_declarationt &declaration);

src/cpp/cpp_typecheck_template.cpp

@@ -48,41 +48,6 @@ void cpp_typecheckt::salvage_default_arguments(
   }
 }
 
-#if 0
-/*******************************************************************\
-
-Function: cpp_typecheckt::check_template_restrictions
-
-  Inputs:
-
- Outputs:
-
- Purpose:
-
-\*******************************************************************/
-
-void cpp_typecheckt::check_template_restrictions(
-  const irept &cpp_name,
-  const irep_idt &final_identifier,
-  const typet &final_type)
-{
-  if(final_type.id()==ID_template)
-  {
-    // subtype must be class or function
-
-    if(final_type.subtype().id()!=ID_struct &&
-       final_type.subtype().id()!=ID_code)
-    {
-      error().source_location=cpp_name.location();
-      error() << "template only allowed with classes or functions,"
-              << " but got `" << to_string(final_type.subtype())
-              << "'" << eom;
-      throw 0;
-    }
-  }
-}
-#endif
-
 /*******************************************************************\
 
 Function: cpp_typecheckt::typecheck_class_template