[RaeF]

What is the meaning of -l in compiler flag, i'm curious.

The definition is: create list file (Preprocess Only) but i don't know what is the meaning of it.

[Nero_3D]

It precompiles your script and output it as .lst file
It resolves the preprocessor directives (#) and adds some information like #file and #line

Example

PHP код:

// This is a comment
// uncomment the line below if you want to write a filterscript
//#define FILTERSCRIPT
#include <a_samp>
#if defined FILTERSCRIPT
    public OnFilterScriptInit() {}
    public OnFilterScriptExit() {}
#else
    main() {}
#endif 


If you leave #define FILTERSCRIPT commented the output would be

PHP код:

// #pragma, sa-mp include ~ 1000 lines, ...
    main() {} 


Otherwise if you uncomment #define FILTERSCRIPT

PHP код:

//...
    public OnFilterScriptInit() {}
    public OnFilterScriptExit() {} 


Normally it does output the correct code, the only exception I know is if you want to check if a function exists which is defined afterwards