ID:13671 VHDL error at <location>: illegal function call in assignment

CAUSE: In an assignment at the specified location in a VHDL Design File (.vhd), you used a Function Call or Type Conversion. However, the Function Call or Type Conversion is illegal in the assignment, for example, a Type Conversion function or the Type Conversion of a formal parameter may be missing a type or contain an incorrect type.

ACTION: Remove the Function Call or Type Conversion, or make sure the Function Call or Type Conversion is legal.