Linker checks all referenced functions

The linker checks definition of all functions referenced in all modules provided in the link command.

Starting with version 2.40, any reference to a function has to be resolved by the linker: When linking a 42r program, if an unused module references an undefined function, the linker (fglrun -l or fgllink) will stop with the error -1338. Before version 2.40, the undefined function was ignored.

Note: Complete function reference is only checked by the linker when creating a 42r program file. When creating a 42x library, there can be references to undefined functions.

In the example, the main.4gl module does not call any function, but the module used in the link line (module.4gl) defines an unused function (f1) calling an undefined function (f2):

main.4gl:

MAIN
    DISPLAY "In main..."
END MAIN

module.4gl:

FUNCTION f1() -- Unused in program
    DISPLAY "In f1..."
    CALL f2() -- Undefined
END FUNCTION

Compiling and linking:

$ fglcomp main.4gl
$ fglcomp module.4gl
$ fgllink -o prog.42r main.42m module.42m
ERROR(-1338):The function 'f2' has not been defined in any module in the program.