| 25 Nov 2024 |
 trofi | * g++ uses libstdc++.so as part of it's implementation. libstdc++ uses g++ to build itself. It's not directly related to the seed. Even after you got the seed you need to build both of those. You need to build both in a single derivation to get them linked against one another (gcc usually builds it in 2 stages internally to untagle from builder's gcc/libstdc++.so, which nixpkgs disables and suffers afterwards, fresh example is https://github.com/NixOS/nixpkgs/issues/342904). | 21:47:55 |
 Alex | Isn't this kind of problem exactly why the Guix bootstrap involves multiple versions of GCC? Obviously, you want to build as few versions as possible and it seems like someone else has already done the hard work of finding a usable path from stage0 to modern GCC. I suppose the main difficulty is porting the build steps to Nix? | 21:58:52 |
 emily | that has already been done | 21:59:24 |
| emily | it doesn't address trofi's concern, which comes up within a GCC build | 21:59:30 |
| Alex | Right, I see now. Nix needs a DAG but it requires hacking into the GCC build system to untangle libstdc++ from g++. | 22:00:54 |
| trofi | Yeah, or patching built binaries after the fact to redirect to fresher libstdc++. | 22:23:26 |
| 26 Nov 2024 |
|  @yannis:mozilla.org changed their display name from yannis|pto_back_nov_26 to yannis. | 07:49:11 |
| 27 Nov 2024 |
 John Ericson | In reply to @trofi:matrix.org
g++ uses libstdc++.so as part of it's implementation. libstdc++ uses g++ to build itself. It's not directly related to the seed. Even after you got the seed you need to build both of those. You need to build both in a single derivation to get them linked against one another (gcc usually builds it in 2 stages internally to untagle from builder's gcc/libstdc++.so, which nixpkgs disables and suffers afterwards, fresh example is https://github.com/NixOS/nixpkgs/issues/342904). I think it is still related | 06:34:27 |
| John Ericson | Nix wants a dag, but the from-scratch bootstrap forces a dag | 06:34:38 |
| John Ericson | in practice, reality does dictate it's a dag | 06:34:47 |
| John Ericson | the way the world get around that in practice is bootstrapping to a fixed point | 06:35:02 |
| John Ericson | * the way the world get around that in practice is bootstrapping to a fixed point, either byte-for-byte or just the ABI | 06:35:20 |
| John Ericson | In reply to @philiptaron:matrix.org
I'm up for a Zoom or other video meetup.
Here's the list of things I'm tracking in stdenv world.
__structuredAttrs https://github.com/NixOS/nixpkgs/issues/205690. Mostly driven by @wolfgangwalthier. Thank you!- Various improvements to fetchgit,fetchGitHub, etc, mostly around
rev vs. tag to increase the expressiveness of the function.
- Improvements to
nixpkgs configuration options to document and regularize those options (https://github.com/NixOS/nixpkgs/pull/330753, but the PR author has left nixpkgs)
- Structured logging (
@nix { "action": "msg", "level": "1", "msg": ...}) support in the stdenv. https://github.com/NixOS/nixpkgs/pull/331794
- Thorough removal of
substituteAll in the nixpkgs codebase: https://github.com/NixOS/nixpkgs/issues/237216
- Continued progress on clarifying what the environment is and what guarantees are possible across "releases".
- Linters and checkers (like
nixpkgs-vet) that assist with in-tree and out-of-tree users to provide diagnostics and migrations for necessary changes.
- Breaking apart the knot of bootstrapping on every platform to enable a stdenv that's "bootstrap-free" -- not strangely constrained by bootstrap concerns, but able to be changed without breaking bootstrap.
- Making sense of how cross-compilation depends and does not depend on stdenv. (This is a personal goal, since I just don't understand it today.)
There are other small things, but this is the majority effort.
Good list! Would like to we the GCC repackaging on that list too :) | 06:35:57 |
| emily | what repackaging? | 06:36:33 |
| trofi | In reply to @Ericson2314:matrix.org
in practice, reality does dictate it's a dag It's a DAG from build step standpoint. But from installation directory standpoint gcc's own bootstrap allows installing libstdc++ and gcc multiple times to make sure both are using one another. nix does not allow for in place file updates and one has to resort to file copies from one store path into another and requires binary patching to achieve the same effect (which is fragile for self-references and effectively requires CA compatibility as a precondition). | 06:56:31 |
| trofi | Luckily gcc is CA-compatible, but glibc is not. As a result I have to use hacks like https://bpa.st/raw/5QWA just to make glibc work in CA (and in cases when I have to rewrite references to relocate glibc) :) | 07:02:13 |
| emily | __FILE__ has been a persistent painful cause of "trivial" self-references / unwanted references for me lately | 07:08:30 |
| emily | not even with CA derivations | 07:08:33 |
| trofi | At least macro expansion should be worked around by https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/compilers/gcc/patches/13/mangle-NIX_STORE-in-__FILE__.patch | 10:50:46 |
| John Ericson | emily: I was working on a branch with Philip Taron (UTC-8) that builds GCC in parts like we do with LLVM | 15:03:08 |
| John Ericson | we are both pressed for time, but I very much want to see it done, as it cuts down on rebuilds and makes cross sane | 15:03:26 |
|  jopejoe1 (4094@epvpn) changed their display name from jopejoe1 to jopejoe1 [4094]. | 18:17:59 |
| emily | I see | 19:10:12 |
| emily | fwiw we probably need to un-split some LLVM stuff since some of it is pretty broken. e.g. Clang having separate lib output breaks unwrapped compilers | 19:10:38 |
| 28 Nov 2024 |
|  shawn8901 left the room. | 18:48:46 |
| shawn8901 joined the room. | 18:50:23 |
| 1 Dec 2024 |
| shawn8901 left the room. | 00:08:07 |
| 10 Dec 2024 |
 Tristan Ross | https://crab.fit/nixpkgs-stdenv-team-meeting-699727 made a crab fit thing to find the availability of everyone so we can work on our updates to give to the SC. | 05:33:42 |
 p14 | Minor quality of life improvements:
- https://github.com/NixOS/nixpkgs/pull/363852
- https://github.com/NixOS/nixpkgs/pull/363855
| 09:12:53 |
| 11 Dec 2024 |
|  @dminca:matrix.org left the room. | 14:19:13 |
