VAR_INPUT and VAR_IN_OUT assignment error

[rarris]

error for variables assignment from VAR_INPUT and VAR_IN_OUT in parameter list
this occurs only if the variables declaration are in the same program
if the vars are in a external function or program declared, there is no error

example:

FUNCTION foo : DINT
VAR_INPUT
input1 : DINT;
END_VAR
VAR_IN_OUT
inout1 : DINT;
END_VAR
VAR_OUTPUT
output1 : DINT;
output2 : DINT;
END_VAR
VAR
var1, var2, var3 : DINT;
END_VAR
foo(input1 := var1, output1 => var2, inout1 := var3);
END_FUNCTION

Could not resolve reference to input1
Could not resolve reference to inout1

Test: https://github.com/PLC-lang/rusty/blob/master/src/codegen/tests/parameters_tests.rs#L7
this test is not the perfect example, the input & in_out vars should be in the same program for 100% reproducibility