static_cast bugfixes when:

- upcasting from generic object to native types ( completely disallowed to upcast object )
- access field on upcast struct from generic csp.Struct type ( Was crashing )

Signed-off-by: Rob Ambalu <robert.ambalu@point72.com>

Author: robambalu

cpp/csp/cppnodes/baselibimpl.cpp

@@ -628,6 +628,9 @@ DECLARE_CPPNODE( struct_field )
     START()
     {
         auto * structType = static_cast<const CspStructType *>( x.type() );
+        //Special check for null meta ( csp.Struct type ) which can end up here from a csp.static_cast
+        if( !structType -> meta() )
+             CSP_THROW( TypeError, "Struct csp.Struct has no field named " << field.value() );
         m_fieldAccess = structType -> meta() -> field( field );
         if( !m_fieldAccess )
             CSP_THROW( TypeError, "Struct " << structType -> meta() -> name() << " has no field named " << field.value() );

csp/baselib.py

@@ -763,8 +763,11 @@ def static_cast(x: ts["T"], outType: "U") -> ts["U"]:
     This should only be used when the caller knows with 100% certainty that the type conversion is always valid
     as there will be no runtime type checking.
     """
-    # Special case bool / int which are native types, but bool evaluates as a subclass of int
-    if not issubclass(outType, x.tstype.typ) or (outType is bool and x.tstype.typ is int):
+    # Allow static_cast on subclass types except for these exceptions:
+    #   - type object which is a base of everything
+    #   - case bool / int which are native types, but bool evaluates as a subclass of int
+
+    if x.tstype.typ is object or not issubclass(outType, x.tstype.typ) or (outType is bool and x.tstype.typ is int):
         raise TypeError(f"Unable to csp.static_cast edge of type {x.tstype.typ.__name__} to {outType.__name__}")
     return Edge(ts[outType], nodedef=x.nodedef, output_idx=x.output_idx, basket_idx=x.basket_idx)
 

csp/tests/test_baselib.py

@@ -1207,6 +1207,7 @@ class D(Base):
         x_int = csp.const(1)
         x_bool = csp.const(True)
         x_float = csp.const(123.456)
+        x_object = csp.const.using(T=object)(1)
 
         x_b = csp.const.using(T=Base)(D(a=1, b=2.1))
 
@@ -1228,10 +1229,22 @@ def g():
         with self.assertRaisesRegex(TypeError, "Unable to csp.static_cast edge of type int to bool"):
             csp.run(csp.static_cast(x_int, bool), starttime=utc_now(), endtime=timedelta())
 
+        with self.assertRaisesRegex(TypeError, "Unable to csp.static_cast edge of type object to int"):
+            csp.run(csp.static_cast(x_object, int), starttime=utc_now(), endtime=timedelta())
+
         # Runtime type check
         with self.assertRaisesRegex(TypeError, 'expected output type on .* to be of type "int" got type "float"'):
             csp.run(csp.dynamic_cast(x_float, int), starttime=utc_now(), endtime=timedelta())
 
+        class S(csp.Struct):
+            a: int
+
+        with self.assertRaisesRegex(TypeError, "Struct csp.Struct has no field named a"):
+            # Was a crash before, dont crash on struct_field access when upcast from csp.Struct which has no metadata
+            csp.run(
+                csp.static_cast(csp.const.using(T=csp.Struct)(S(a=1)), S).a, starttime=utc_now(), endtime=timedelta()
+            )
+
 
 if __name__ == "__main__":
     unittest.main()