DDraceNetwork - developer

Hey @heinrich5991 , Broken led me to you that you might have the f33 map. If you have it, can you send it to me please?

ChillerDragon, could you not make the repo public...

05:14

oh. it is not public. wondered why I had access out of the box

05:14

lol

hello world

1

@heinrich5991 yo, can you pls explain why this code works:

struct Foo<'a> {
    u: &'a usize,
}

impl<'a> Foo<'a> {
    fn new() -> Self {
        Self { u: &10 }
    }

    fn test(&'a self) {}
}

fn main() {
    let foo = Foo::new();
    foo.test();
    drop(foo);
}

But if method test is changed to fn test(&'a mut self) it doesn't work, it says it can't move out foo because it's borrowed, isn't it also borrowed without mut? :\

https://doc.rust-lang.org/nomicon/subtyping.html I think it's related xd

1

time to learn about elf relocatable files

07:05

im writing my own compiler backend

ok i know how now

"I know Kung Fu"

wdym xD

08:27

pub fn build_object() {
    let mut builder = build::elf::Builder::new(object::Endianness::Little, true);
    builder.header.e_type = elf::ET_REL;
    builder.header.e_machine = elf::EM_X86_64;
    builder.header.e_phoff = 0x40;

    let section = builder.sections.add();
    section.name = b".shstrtab"[..].into();
    section.sh_type = elf::SHT_STRTAB;
    section.data = build::elf::SectionData::SectionString;

    let section = builder.sections.add();
    section.name = b".strtab"[..].into();
    section.sh_type = elf::SHT_STRTAB;
    section.data = build::elf::SectionData::String;

    let section = builder.sections.add();
    section.name = b".text"[..].into();
    section.sh_type = elf::SHT_PROGBITS;
    section.sh_flags = (elf::SHF_ALLOC | elf::SHF_EXECINSTR) as u64;
    section.sh_addralign = 16;
    // program data goes here.
    let my_func_data: Vec<u8> = vec![
        0xf3, 0x0f, 0x1e, 0xfa, // endbr64
        0x55, // push   %rbp
        0x48, 0x89, 0xe5, // mov    %rsp,%rbp
        0xc7, 0x45, 0xfc, 0x00, 0x00, 0x00, 0x00, //  movl   $0x0,-0x4(%rbp)
        0xb8, 0x02, 0x00, 0x00, 0x00, // mov    $0x2,%eax
        0x5d, // pop    %rbp
        0xc3, // ret
    ];
    let my_func_data_size = my_func_data.len();
    section.data = build::elf::SectionData::Data(my_func_data.into());
    let text_id = section.id();

    let section = builder.sections.add();
    section.name = b".symtab"[..].into();
    section.sh_type = elf::SHT_SYMTAB;
    section.sh_flags = elf::SHF_ALLOC as u64;
    section.sh_addralign = 8;
    section.data = build::elf::SectionData::Symbol;

    let symbol = builder.symbols.add();
    symbol.name = b".text"[..].into();
    symbol.set_st_info(elf::STB_LOCAL, elf::STT_SECTION);
    symbol.section = Some(text_id);

    // Add symbols
    let symbol = builder.symbols.add();
    symbol.name = b"main"[..].into();
    symbol.set_st_info(elf::STB_GLOBAL, elf::STT_FUNC);
    symbol.st_size = my_func_data_size as u64;
    symbol.section = Some(text_id);
    // offset to the function within .text
    // Note: i think it needs to be 16 byte aligned
    symbol.st_value = 0;

    builder.set_section_sizes();

    let mut file = StreamingBuffer::new(BufWriter::new(File::create("out.o").unwrap()));
    builder.write(&mut file).unwrap();
}

08:27

this is how to make a relocatable object file (edited)

08:27

this crate is neat

08:28

i think they use it in rustc

Matrix reference: https://www.youtube.com/watch?v=0YhJxJZOWBw

Blu-ray Clips

The Matrix - 'I Know Kung Fu'

oh xD

def-

[ddnet-web:master] 1 new commit

6d57020 New UKR server - def-

Pathos

Hey @heinrich5991 , Broken led me to you that you might have the f33 map. If you have it, can you send it to me please?

my map archive is at https://heinrich5991.de/teeworlds/maps/maps/

09:02

I can see a single f33 map there, search for f33_

1

MilkeeyCat

@heinrich5991 yo, can you pls explain why this code works:

struct Foo<'a> {
    u: &'a usize,
}

impl<'a> Foo<'a> {
    fn new() -> Self {
        Self { u: &10 }
    }

    fn test(&'a self) {}
}

fn main() {
    let foo = Foo::new();
    foo.test();
    drop(foo);
}

But if method test is changed to fn test(&'a mut self) it doesn't work, it says it can't move out foo because it's borrowed, isn't it also borrowed without mut? :\

the problem is that the mutable reference makes the inner type invariant wrt. the lifetime. your link is indeed the explanation

09:04

in general, you shouldn't tie the inner lifetime to the lifetime of the self reference

09:04

that would avoid some of your troubles

I understand that you should reevaluate your life decisions which led you to using same lifetime for self, I tried to read about this invariant stuff and I don't get what changes when type is invariant, covariant or contravariant

generally, if you have a function that takes a &'a i32 reference, the rust compiler also allows you to pass a reference that lives longer

09:09

e.g. a &'static i32

09:09

does that make sense?

ye

but if you have a function that takes &'static mut &'a i32, rust mustn't allow you to pass a &'static mut &'static i32. why?

I would allow that

then the function can put in another &'a i32, one that actually only lives for 'a into that outer &'static mut

09:18

once the function returns, the caller thinks it has a &'static mut &'static i32, but the inner reference actually only lives for 'a

where chlindr dragon(#

<ChillerDragon> im here

got an alert for "dragon"? ^^

<ChillerDragon> no i just read here a lot^^

09:23

<ChillerDragon> @jxsl13 i invited you. Your gitlab name was not hard to guess.

@MilkeeyCat does that make sense?

heinrich5991

@MilkeeyCat does that make sense?

nope, but thanks for trying to explain xd. I'll keep reading this and maybe later it will make sense

@MilkeeyCat maybe you simply overthink it. Do you understand the implicit lifetime your foo object gets? If you do &'a mut self, then rust wants your self argument to have exactly 'a lifetime nothing else - So in your case it must assume self is static (or whatever &32 gets) bcs that is kinda what invariant is. Just take that and don't think any further (edited)

10:20

@MilkeeyCat What are you even doing every day that you find the edgiest edge cases in Rust all the time

10:21

You want references of local variables in function results

10:21

Now this xD

I just found a comment in other person's project

hi

1

can we move developer channel so newbies dont type here

1

12:05

This is so cursed

12:05

bieban

cool website xd

1

@deen or @heinrich5991 can u move the category development back to its position?

Ryozuki

@deen or @heinrich5991 can u move the category development back to its position?

Why so?

its not pleasing