Program Entry Point Details

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As you’ve seen, the entry point of your program is called main, it returns void and does not take any arguments.
But, wait, shouldn’t it be a main :: (argc : s32, argv : **u8) -> s32 like in other languages instead ? Well not in Jai! Jai has an intermediate step, where it initialize a few things such as the context, and the command line arguments are cached in the __command_line_arguments array.
The actual entry point of your program is called __system_entry_point, and can be found in modules/Runtime_Support.jai:

#program_export
__jai_runtime_init :: (argc: s32, argv: **u8) -> *Context #c_call {
    __command_line_arguments.count = argc;
    __command_line_arguments.data  = argv;

    ts := *first_thread_temporary_storage;
    ts.data = first_thread_temporary_storage_data.data;
    ts.size = TEMPORARY_STORAGE_SIZE;

    ts.original_data = first_thread_temporary_storage_data.data;
    ts.original_size = TEMPORARY_STORAGE_SIZE;
    
    first_thread_context.temporary_storage = ts;

    return *first_thread_context;
}

#program_export
__jai_runtime_fini :: (_context: *void) #c_call {
    // Nothing here for now!
}

#program_export "main"
__system_entry_point :: (argc: s32, argv: **u8) -> s32 #c_call {
    __jai_runtime_init(argc, argv);

    push_context first_thread_context {
        __program_main :: () #runtime_support;
        __program_main();
    }
    
    return 0;
}

So, you can see that this procedure does take a s32 and a **u8, and returns a s32. It is also marked as #c_call, and is exported as main so the OS can find it.
This procedure is responsible for initializing the context, temporary_storage, and the __command_line_arguments array by calling __jai_runtime_init, defined right before. It then calls __program_main, which is the main you’ve defined, after pushing the newly created context.