Using comptime function that require option will end in declaration loop

[mathk]

Microzig redefine the std_option with specific entry for embedded device. Like interrupt or chip/hal config.
By doing so it allow users to fine tune the MCU. This have some limitation on how microzig_options can be initialized.

std_option is being shadow and whenever attribute inside the microzig_options need std_option it will trigger a declaration loop error.

This happen for example when you want to format string:

pub fn DMA(index: u32, channel: u32) type {

    // /!\   This line will trigger the declaration loop if you include the DMA_Handler
   // inside the microzig_option since this comptimePrint needs std_option.
    const interrupt_name = std.fmt.comptimePrint("DMA{}_Channel{}", .{ index, ch});
    const interrupt_index = blk: for (microzig.chip.interrupts) |*interrupt| {
        if (std.mem.eql(u8, interrupt_name, interrupt.name)) {
            break :blk interrupt.index;
        }
    } else @panic("Interrupt index not found");

    return struct {
        var channel: ?Channel = null;

        pub fn DMA_Handler() callconv(.c) void {
            const event = read_events();
            clear_events(event);
            if (channel) |*init_chan| {
                init_chan.deliver_event(event);
            }
        }
       ...
    }
 ...
}

[mattnite]

This a downstream issue of #465. When we finally make the user's app root, we'll take out std_options from microzig_options and this will no longer be an issue.