2024-03-11 Nix team meeting minutes #132


Discrepancy in `outputs` handling between derivation / derivationStrict · Issue #7569 · NixOS/nix · GitHub

WIP vision for builders data model (build capabilities) by roberth · Pull Request #9899 · NixOS/nix · GitHub

  • Still a WIP
  • Remote builder format suboptimal. Attempt at improving the internal representation and data model.

Expose new-cli `--json` commands in the repl · Issue #10108 · NixOS/nix · GitHub

  • expose nix CLI commands in REPL
  • needs feedback

git-lfs support by b-camacho · Pull Request #10153 · NixOS/nix · GitHub

  • Already agreed this was something we wanted provided it’s not too intrusive. And that one isn’t, so that’s cool :slight_smile:
  • @roberth will look at it
    • Will need a test
    • Seems surprising and concerning that it works at all
    • Appears to rely on alternative Nix code path that accesses worktree files directly. We should probably not do that.

flakeref: follow symlinks by con-f-use · Pull Request #9499 · NixOS/nix · GitHub

  • assigned

Don't have root bypass the daemon by default · Issue #10140 · NixOS/nix · GitHub

  • root or write-access to /nix/store will bypass daemon
  • Needs to benchmark a bit to show the performance impact on things like nixos-rebuild

feat: tab support for indentation stripping by thecaralice · Pull Request #9971 · NixOS/nix · GitHub

  • [@tomberek]: Deferring to @pennae to know whether that should wait until the parser rewrite is done

Fix `nix eval nixpkgs#bash` segfault by 9999years · Pull Request #10200 · NixOS/nix · GitHub

  • nix eval should print drvPath instead of infinite looping
  • @roberth: It just does too much. There’s no need to recurse into everything. Print a single Value only?
  • @tomberek: Should it be drvPath?
    • outPath would be more consistent, but sometimes non-existent
  • Approved, but needs a release note (and a test)

Add `builtins.toStringDebug` by 9999years · Pull Request #10206 · NixOS/nix · GitHub and Add 'poison' context by 9999years · Pull Request #10212 · NixOS/nix · GitHub

  • @roberth: Makes errors distinguishable in-language, exposing evaluation order, etc, by doing string matching etc.

Only print the first line of errors in values by 9999years · Pull Request #10207 · NixOS/nix · GitHub

  • How can users know that there’s more to the error?
  • How do they get the whole message? Getting the attribute by hand could be annoying.
  • Potential alternative design: Print the errors at the end like footnotes or interactively
nix-repl> foo
{ foo = <<error, see :error 1>>; bar = <<error, see :error 2>>; }

nix-repl> :error 1

For top-level errors, print the whole thing, as before.

If the top-level thing is a package, make sure it also prints the whole error, as before.

Make `TypeError` structured by 9999years · Pull Request #10199 · NixOS/nix · GitHub

  • Reminescent of something @ericson2314 tried in the past, assigned to him.

Meta: getting back on our goals

  • We’re getting stuck on the day-to-day again

  • Tried to raise contributions around the CLI in the past with mixed success

    • Maybe announce on discourse? An ongoing thread in the style of Nixpkgs PRs ready for review.

FetchTree stabilization

  • Make `builtins.fetchTree` return a path as its `outPath` element · Issue #10115 · NixOS/nix · GitHub

    • proposal to change output type to “path” vs “string w/context”
  • “virtual strings” - lazy strings

  • proposal: lazy paths

    • lazy-trees support for paths without support for laziness in strings
    • fetchTree
    • interpolation name of a lazy-path == “source” or the name, only at the root
  • explore “lazy paths”

    • Is it feasible to implement?
    • Does it differ from lazy-trees, and how?
    • Reconcilation? Bad to end up with another kind of laziness
      • If the changes are part of lazy-trees (prev question), this is not a problem
    • Does this end up being useful in practice?
    • Module system error messages show path to module
      • just to print error message
      • paths sometimes used as attrset keys
    • dirOf changes
    • determine if this causes Nixpkgs/NixOS hash changes
    • timebox (<1 week)
    • there is a branch that has much of this
    • … coordination …
    • perform Nixpkgs+FlakeHub regression tests
  • alternative: __toString in fetchTree return value

    • too awkward?
  • alternative: addToStore can detect and prevent double-copy

    • cons: likely historical hash changes
      • maybe detect special “lazy path” case? seems too ad hoc
    • pros: consistency
  • alternative: keep output as string

    • requires “virtual strings” to be performant
      • strings with a lazy-path context
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