emanote: patch out erroneous runtime deps due to cabal _Path module

[edrex]

Patch emanote static binary's dependencies to remove erroneous references due to Cabal *_Path modules.

Reduces closure size for static executable reported by nix path-info -S ./result from 5643632280
to 570510096

• Follow-up to emanote: init at 0.8.0.0 #199442

What I did:

• Duplicated pandoc: remove GHC from the runtime closure (2.4GB -> 180MB) #86194 but for emanote
• Added extra deps shown by nix-tree ./result to the list of disallowed packages (pandoc, warp).
• Noted smaller closure size
• Removed overrides until the closure got big again.

Things done

• Built on platform(s)
  • x86_64-linux
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)

[edrex]

request reviews: @maralorn @srid @Profpatsch

[edrex]

Note that this kind of patch should be obsoleted if/when haskell/cabal#8534 lands and affected programs are patched to use the new mechanism for discovering/embedding dependency versions.

[srid]

5.5G to 0.5G reduction in size? Great!

[edrex]

Note that emanote still has a runtime dependency on nodejs via tailwindcss, which accounts for most of the remaining size.

[srid]

Note that emanote still has a runtime dependency on nodejs via tailwindcss, which accounts for most of the remaining size.

Tangential, but I really want to rewrite the Tailwind compiler in Haskell. It would also help srid/ema#20 in addition to srid/emanote#384 (comment)

[edrex]

I notice that nix-build -A emanote causes both an executable and library build:

• Building executable 'emanote' for emanote-0.8.0.0..
• Building library for emanote-0.8.0.0..

That seems sensible but also the library isn't present in ./result/ so I feel like something funny is going on. Can anybody explain why the library is being built here? This happens without this patch too.

[maralorn]

Hey @edrex generally the Haskell derivations in nixpkgs build all build outputs of a package, i.e. the library (if it exists) and all executables. This makes a lot of sense because in most Haskell packages the executable depends on the library, so it is needed for compilation. (There is a flag in our mkDerivation script to disable building the library, but for the before mentioned reason that will result in a build fail for most packages.)
When we use the justStaticExecutables function, the executables get linked statically and after that the library gets removed. This happens to reduce closure size, because the library contains references to store paths not needed by the statically linked executable. We cannot simply not build the library because it is needed at compile time.