stack: prefer a committed .cabal over re-running hpack (#626, #767) - #2547
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hamishmack wants to merge 1 commit into
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stack: prefer a committed .cabal over re-running hpack (#626, #767)#2547hamishmack wants to merge 1 commit into
hamishmack wants to merge 1 commit into
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In the stack path, findCabalFiles UsePackageYamlFirst always re-rendered a package.yaml through hpack whenever it existed, even when the package directory also contained a committed .cabal file. This discarded the committed file and historically failed outright when the .cabal had been hand-modified or was produced by a newer hpack. The cabalProject path already prefers a committed .cabal (call-cabal-project-to-nix.nix skips hpack when a .cabal exists). Mirror that in the stack path: use the on-disk .cabal when present, falling back to hpack only when there is no .cabal. --ignore-package-yaml continues to force cabal-only discovery. Adds a self-contained (no external tools/network) test-suite stack-project-tests exercising findCabalFiles.
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Summary
In the stack path,
findCabalFiles UsePackageYamlFirst(nix-tools/nix-tools/lib/Stack2nix/Project.hs) unconditionally re-rendered apackage.yamlthrough hpack whenever it existed — even when the package directory also contained a committed.cabalfile. This discards the committed file and historically failed outright with errors like ".cabal was generated with a newer version of hpack, please upgrade" (#626) or ".cabal was modified manually, please use --force" (#767).The cabal path already prefers a committed
.cabal(lib/call-cabal-project-to-nix.nixskips hpack for apackage.yamlwhen a.cabalexists — "Ignoring $hpackFile as $cabalFile exists"). This change mirrors that policy in the stack path: use the on-disk.cabalwhen present, and fall back to hpack only when there is no.cabal.--ignore-package-yaml(IgnorePackageYaml) continues to force cabal-only discovery.Tests
Adds a self-contained test-suite
stack-project-tests(only touches a temp dir — no external tools, no network, no extra test-framework deps) asserting thatfindCabalFiles:.cabalwhen both files exist (the Do not call hpack if .cabal exists #626/.cabal was modified manually, please use --force to overwrite. #767 regression),package.yamlexists,.cabalwhen only a.cabalexists,package.yamlunderIgnorePackageYaml.Verification
.cabalpresent vs. absent); the missing-dir / no-package.yamlbehaviour is unchanged.cabal checkpasses (only pre-existing PVP upper-bound warnings, unrelated to this change).Notes
findCabalFilesinplan2nix/Plan2Nix/Project.hsis left as-is: the cabal path already handles this at the Nix layer, and de-duplicating the two copies is out of scope here (related to the cache-module dedup theme in Drop duplicate code #1689).--use-package-yamlopt-out (to force stack's regenerate-always behaviour) was considered but skipped to keep the change minimal; it isn't offered on the cabal path either. Easy to add later if wanted.Closes #626.
Closes #767.