Ensure co_consts doesn't provide python access to a raw java array

At some point in jinja2.loaders, the code object for the function load gets hashed. Since
this function contains the list view ['root'], it used to be placed into co_consts as
a singleton Object[] containing a TruffleString. This then made the hash crash. This
way it is stored as a tuple and can get hashed normally, fixing the issue

Author: Adam Hrbac

graalpython/com.oracle.graal.python.test/src/tests/test_code.py

@@ -249,3 +249,10 @@ def inner():
         if type(const) == types.CodeType:
             code = const
     assert "this is fun" in code.co_consts
+
+
+def test_consts_do_not_leak_java_types():
+    codestr = "['root']"
+    code = compile(codestr, '<test>', 'exec')
+    for const in code.co_consts:
+        assert isinstance(const, (str, tuple)) or const is None

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/code/PCode.java

@@ -79,6 +79,7 @@
 import com.oracle.graal.python.nodes.generator.GeneratorFunctionRootNode;
 import com.oracle.graal.python.nodes.literal.SimpleLiteralNode;
 import com.oracle.graal.python.nodes.literal.TupleLiteralNode;
+import com.oracle.graal.python.nodes.object.IsForeignObjectNode;
 import com.oracle.graal.python.runtime.GilNode;
 import com.oracle.graal.python.runtime.PythonContext;
 import com.oracle.graal.python.runtime.object.PythonObjectFactory;
@@ -633,7 +634,12 @@ private static Object convertConstantToPythonSpace(RootNode rootNode, Object o)
             Object[] array = new Object[strings.length];
             System.arraycopy(strings, 0, array, 0, strings.length);
             return factory.createTuple(array);
+        } else if (o instanceof Object[]) {
+            Object[] objects = (Object[]) o;
+            return factory.createTuple(objects.clone());
         }
+        // Ensure no conversion is missing
+        assert !IsForeignObjectNode.getUncached().execute(o);
         return o;
     }