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Show HN: A 166 KB file for cross compiling glibc for any version, any target

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Re: Show HN: A 166 KB file for cross compiling glibc for any version, any target

#11

Post by Spex_guy »

lhorie wrote: post #10
AndyKelley wrote: post #2

Some context: In master branch of Zig right now (before https://github.com/ziglang/zig/pull/10330 is merged), status quo: $ cat ../lib/libc/glibc/*.txt | wc -c 205219 $ cat ../lib/libc/glibc/*.txt | xz | wc -c 22976 Zig supports targeting every version of glibc for any target architecture. The information required to do this takes up 200 KB installation size / 22 KB tarball size, and it has the following problems (wh…

How much work is it to then maintain this bespoke encoding? Without having much context on it, it sounds similar to having to maintain unicode identifier character tables for unicode-aware parsers (e.g. Javascript's). Updating unicode tables after unicode version releases can be done w/ somewhat hack-ish scripting of parsing txt spec files but it's admittedly not super clean, I'm curious what's involved when dealing…

The process of adding new versions of glibc to the data set is described in the readme. If something changes in a way the format doesn't handle, we can just change it and update the code in the compiler at the same time. The file ships as part of the compiler distribution so we don't have to worry about backwards compatibility.

Re: Show HN: A 166 KB file for cross compiling glibc for any version, any target

#13

Post by Spex_guy »

formerly_proven wrote: post #4
AndyKelley wrote: post #2

Some context: In master branch of Zig right now (before https://github.com/ziglang/zig/pull/10330 is merged), status quo: $ cat ../lib/libc/glibc/*.txt | wc -c 205219 $ cat ../lib/libc/glibc/*.txt | xz | wc -c 22976 Zig supports targeting every version of glibc for any target architecture. The information required to do this takes up 200 KB installation size / 22 KB tarball size, and it has the following problems (wh…

Totally off-topic: I installed Zig on Saturday afternoon and by the evening I had my first program do some useful stuff, on Sunday I added some C code, then added some tests and by Sunday evening I had a pure Zig project again (and afterwards learned that translate-to-zig is a thing). I gotta say I'm very impressed with Zig and partial evaluation is just such a nice, mentally simple technique for generics and lots of…

Your instinct is right about array types, semantically in Zig they are passed by value. Parameter values are always const though, which allows the compiler to sometimes use pass-by-const-ref to avoid copying large pieces of data. Since arrays are proper value types, we can also make strongly typed pointers to them, like `*[3][4]u32`.

Re: Show HN: A 166 KB file for cross compiling glibc for any version, any target

#14

Post by dnautics »

nyanpasu64 wrote: post #9
dnautics wrote: post #8

Earlier quoted context omitted.

> the prefix-[] are kinda weird (just way too used to C/C++'s postfix array notation) I think over time the C/C++ way is going to go the way of the dodo; IIRC, rust and go both use the prefix-[]. It creates a clear, unambiguous way of defining the type (no "spiral typing" jokes for the modern languages).

I wish Rust used prefix &[]i32 for a slice, and [5][2]i32 for a 5x2 array. Instead it uses &[i32] for a slice, and [[i32; 2]; 5] for a 5x2 array. Reading types backwards is alive and well.

eh, the type surrounded by the [] "operator" is equally unambiguous as prefix-[], so it's not the worst.

Re: Show HN: A 166 KB file for cross compiling glibc for any version, any target

#15

Post by klodolph »

richardwhiuk wrote: post #12

What's the point in this? Surely you'll have more dependencies than glibc?

You will, but glibc is a common dependency on a dynamic lib. It's nice to be able to compile something and target an old glibc so your program can run on old systems (and by "old" I'm just talking about LTS).

Re: Show HN: A 166 KB file for cross compiling glibc for any version, any target

#16

Post by laserbeam »

jokoon wrote: post #7

Oh, zig is not in https://learnxinyminutes.com/ , someone should add it :)

I'd wait for zig 1.0 or 1.1 before that. Syntax may still change a bit and it would be a shame to maintain that.

The zig language doc is pretty good and short, and the lib/std folder is full of pretty easy to understand examples.

Re: Show HN: A 166 KB file for cross compiling glibc for any version, any target

#17

Post by mmastrac »

nyanpasu64 wrote: post #9
dnautics wrote: post #8

Earlier quoted context omitted.

> the prefix-[] are kinda weird (just way too used to C/C++'s postfix array notation) I think over time the C/C++ way is going to go the way of the dodo; IIRC, rust and go both use the prefix-[]. It creates a clear, unambiguous way of defining the type (no "spiral typing" jokes for the modern languages).

I wish Rust used prefix &[]i32 for a slice, and [5][2]i32 for a 5x2 array. Instead it uses &[i32] for a slice, and [[i32; 2]; 5] for a 5x2 array. Reading types backwards is alive and well.

I prefer the unambiguous nesting of Rust's style. I can never remember the array shape when array bounds are listed in either prefix or postfix style. It's a tiny bit of extra typing that ensures that my understanding of the code is always 100% correct.

Re: Show HN: A 166 KB file for cross compiling glibc for any version, any target

#19

Post by gavinray »

AndyKelley wrote: post #2

Some context: In master branch of Zig right now (before https://github.com/ziglang/zig/pull/10330 is merged), status quo: $ cat ../lib/libc/glibc/*.txt | wc -c 205219 $ cat ../lib/libc/glibc/*.txt | xz | wc -c 22976 Zig supports targeting every version of glibc for any target architecture. The information required to do this takes up 200 KB installation size / 22 KB tarball size, and it has the following problems (wh…

Can I use this incredible feature with other toolchains, or existing artifacts that have a glibc dependency?

Say if I am using a language/toolchain which pulls in a C/C++ compiler, are you able to substitute "zig cc" there and explicitly cross-compile to a different GLIBC version?

Re: Show HN: A 166 KB file for cross compiling glibc for any version, any target

#20

Post by AndyKelley »

gavinray wrote: post #19
AndyKelley wrote: post #2

Some context: In master branch of Zig right now (before https://github.com/ziglang/zig/pull/10330 is merged), status quo: $ cat ../lib/libc/glibc/*.txt | wc -c 205219 $ cat ../lib/libc/glibc/*.txt | xz | wc -c 22976 Zig supports targeting every version of glibc for any target architecture. The information required to do this takes up 200 KB installation size / 22 KB tarball size, and it has the following problems (wh…

Can I use this incredible feature with other toolchains, or existing artifacts that have a glibc dependency? Say if I am using a language/toolchain which pulls in a C/C++ compiler, are you able to substitute "zig cc" there and explicitly cross-compile to a different GLIBC version?

Yep! Example: https://dev.to/kristoff/zig-makes-go-cross-compilation-just-...
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