Repository navigation
chore(deps): remove the nixpkgs-25 regex-pcre pkg-config/pcre override once stock regex-pcre builds at the channel rev #5447
Description
Context
The 2026-11-04 nixpkgs update (tracking: #2715) moves nixpkgs-25 e7439b6b -> 1d060086 (the Hydra-gated nixos-unstable channel revision). At the new revision, haskellPackages.regex-pcre (pulled into the amd system closure via haskellPackages.misfortune in nixos/environment/default.nix) is marked broken under nixpkgs' problems framework, and the marking is honest: with the broken flag warned through, its build fails deterministically in the configure phase --
Error: [Cabal-7620]
The program 'pkg-config' version >=0.9.0 is required but it could not be found.
nixpkgs' Haskell builder no longer adds the pkg-config wrapper (or the pkgconfig-depends libraries) to Haskell build environments -- the same mechanism the 2026-10-30 run hit on the master pin (that instance is tracked in #3906). Drew ruled on 2026-11-04 ("fix it or pin misfortune") to revive the #3906-class override for the nixpkgs-25 segment rather than keep the input frozen.
The temporary override
nixos/environment/default.nix extends the raw nixpkgs-25 legacyPackages segment with an overlay that overrides haskellPackages.regex-pcre to append pkg-config to its nativeBuildInputs and a minimal vendored pcre 8.45 (the version the old pins shipped; test suite disabled) to its buildInputs, restoring the old build environment for this one package. A problems handler scoped to regex-pcre warns the broken marking through so the overridden derivation can evaluate.
Removal condition
Remove the override when the stock (un-extended) nixpkgs-25 segment's haskellPackages.regex-pcre builds at the then-current channel pin -- i.e. it is no longer marked broken, or warned through it builds because nixpkgs' Haskell builder once again provides pkg-config in its build environment -- or when regex-pcre/misfortune leaves the amd closure (for example if the nixpkgs-25 pin exception from #3327 is retired entirely).
Removal test
Revert the segment in nixos/environment/default.nix to the raw inputs.nixpkgs-25.legacyPackages and remove the override binding, then build the segment's haskellPackages.misfortune (which realises regex-pcre) and the full amd toplevel; both must succeed.
Acceptance criteria
- The removal condition is verified, not assumed: the stock
nixpkgs-25haskellPackages.regex-pcreat the current pin is not refused for broken problems and realises successfully, OR regex-pcre/misfortune has left theamdclosure. - If the condition holds: the override in
nixos/environment/default.nixis removed and both the segment'shaskellPackages.misfortuneand the fullamdtoplevel build succeed. - If the condition does not hold yet: the check result (date + nixpkgs-25 revision + what was observed) is recorded on this issue and the override stays.
Activity
developing-today commentedon Nov 4, 2026
CODE-1323
fix(nixos): restore regex-pcre build env on the nixpkgs-25 segment
dezren39 commentedon Nov 4, 2026
Override landed 2026-11-04 with PR #5453 (merged, merge commit
44b2dd56e), under Drew's ruling on #2715. Thenixpkgs-25-fixedbinding is live on main innixos/environment/default.nix; its comment names this issue, #2715, the removal condition, and the removal test stated here. Verified at landing: the toplevel closure carries the overridden regex-pcre drv (5xl002q8..., solo-realised, store-valid) and the full amd toplevel built from the committed tree (outputjiz6p50b..., hashsha256:087qi62555v3155jdw59x50wyi5mk3kj8cwk5ap2brgrg28fzb9d). This issue stays open until the removal condition is verified at a futurenixpkgs-25pin.dezren39 commentedon Nov 5, 2026
agent-note:v1
dezren39 commentedon Nov 5, 2026
agent-note:v1
Triage check 2026-11-05 (task 10042): removal condition does NOT hold yet — override stays.
Evidence, verified at current main (laptop ~/git/code on main @ 04f7869, matching origin):
flake.locknixpkgs-25 pin is still1d060086d60cb76a40cf37109f979d88a5bd6396— unchanged since the override landed with PR chore(deps): nixpkgs update 2026-11-04 #5453 on 2026-11-04.nixpkgs-25.legacyPackages.x86_64-linux.haskellPackages.regex-pcre.meta.broken = true(position: pkgs/development/haskell-modules/hackage-packages.nix in that pin). So the stock segment still refuses regex-pcre for broken problems, exactly the condition the override innixos/environment/default.nix(thenixpkgs-25-fixedbinding) works around.nixpkgs-25-fixed.haskellPackages.misfortuneis still in the environment package list.Ordering / next trigger: re-check this issue when the nixpkgs-25 pin next moves (tracking: #2715) or if misfortune/regex-pcre leaves the amd closure. At that point run the removal test from the issue body (revert to raw legacyPackages, build the segment's haskellPackages.misfortune and the full amd toplevel).