C++ front-end: support pointer to non-method members

regression/cpp/pointer_to_member_conversion1/test.desc

@@ -1,10 +1,7 @@
-KNOWNBUG
+CORE
 main.cpp
 
 ^EXIT=0$
 ^SIGNAL=0$
-^VERIFICATION SUCCESSFUL$
 --
 ^warning: ignoring
---
-should exercise cpp_typecheckt::standard_conversion_pointer_to_member, cpp/cpp_typecheck_conversion.cpp:610 once other bugs are fixed

regression/cpp/pointer_to_member_conversion2/test.desc

@@ -1,11 +1,9 @@
-KNOWNBUG
+CORE
 main.cpp
 
 ^EXIT=(64|1)$
 ^SIGNAL=0$
-invalid implicit conversion
+pointer-to-member type error
 ^CONVERSION ERROR$
 --
 ^warning: ignoring
---
-should exercise cpp_typecheckt::standard_conversion_pointer_to_member, cpp/cpp_typecheck_conversion.cpp:610 once other bugs are fixed

src/cpp/cpp_typecheck_conversions.cpp

@@ -1595,9 +1595,11 @@ bool cpp_typecheckt::cast_away_constness(
 
   if(is_reference(nt1))
     nt1.remove(ID_C_reference);
+  nt1.remove("to-member");
 
   if(is_reference(nt2))
     nt2.remove(ID_C_reference);
+  nt2.remove("to-member");
 
   // substitute final subtypes
   std::vector<typet> snt1;
@@ -2021,6 +2023,21 @@ bool cpp_typecheckt::static_typecast(
         return true;
       }
     }
+    else if(
+      type.find("to-member").is_nil() &&
+      e.type().find("to-member").is_not_nil())
+    {
+      if(type.subtype() != e.type().subtype())
+        return false;
+
+      struct_typet from_struct = to_struct_type(
+        follow(static_cast<const typet &>(e.type().find("to-member"))));
+
+      new_expr = e;
+      new_expr.type().add("to-member") = from_struct;
+
+      return true;
+    }
     else
       return false;
   }

src/cpp/cpp_typecheck_expr.cpp

@@ -748,6 +748,13 @@ void cpp_typecheckt::typecheck_expr_address_of(exprt &expr)
       }
     }
   }
+  else if(
+    expr.op0().id() == ID_ptrmember && expr.op0().op0().id() == "cpp-this")
+  {
+    expr.type() = pointer_type(expr.op0().type());
+    expr.type().add("to-member") = expr.op0().op0().type().subtype();
+    return;
+  }
 
   // the C front end does not know about references
   const bool is_ref=is_reference(expr.type());
@@ -2626,13 +2633,6 @@ void cpp_typecheckt::convert_pmop(exprt &expr)
     throw 0;
   }
 
-  if(expr.op1().type().subtype().id()!=ID_code)
-  {
-    error().source_location=expr.find_source_location();
-    error() << "pointers to data member are not supported" << eom;
-    throw 0;
-  }
-
   typecheck_expr_main(expr.op1());
 
   if(expr.op0().type().id()!=ID_pointer)

src/cpp/cpp_typecheck_initializer.cpp

@@ -133,6 +133,9 @@ void cpp_typecheckt::convert_initializer(symbolt &symbol)
 
     typecheck_expr(symbol.value);
 
+    if(symbol.value.type().find("to-member").is_not_nil())
+      symbol.type.add("to-member") = symbol.value.type().find("to-member");
+
     if(symbol.value.id()==ID_initializer_list ||
        symbol.value.id()==ID_string_constant)
     {

src/cpp/cpp_typecheck_resolve.cpp

@@ -309,11 +309,16 @@ exprt cpp_typecheck_resolvet::convert_identifier(
       }
       else
       {
-        // this has to be a method
+        // this has to be a method or form a pointer-to-member expression
         if(identifier.is_method)
           e=cpp_symbol_expr(cpp_typecheck.lookup(identifier.identifier));
         else
-          e.make_nil();
+        {
+          e.id(ID_ptrmember);
+          e.copy_to_operands(
+            exprt("cpp-this", pointer_type(compound_symbol.type)));
+          e.type() = type;
+        }
       }
     }
   }