Encountered a function that was never defined.

#2030   Compile-time error

Encountered a function that was never defined.

Additional Information

The function 'X' was first predefined on line N of file 'F'.
The conversion function was first predefined on line N of file 'F'.
    in case the function was predefined with define conversion-function.

Recovery

Compilation continues but no compiled source code file will be saved.

Explanation

All functions must be declared before they are used. The body of the function may be given anywhere in a program (thereby defining the function), but its heading must appear at least once before its first use.