Make our repo buildable again with -O0.

[bezirg]

I am developing with -O0 which can cut build times in most cases. This makes our repo buildable with -O0.

Also this patch might help with hls and lsp, not 100% sure.

If you don't likek this patch, I can drop it and only keep it locally.

[github-actions]

PR Preview Action v1.6.2
🚀 View preview at https://IntersectMBO.github.io/plutus/pr-preview/docs/pr-7262/
Built to branch gh-pages at 2025-09-30 17:35 UTC. Preview will be ready when the GitHub Pages deployment is complete.

[github-actions]

Execution Budget Golden Diff

3179337 (master) vs 3b2a51b

output

plutus-benchmark/nofib/test/9.6/knights10-4x4.eval.golden

Metric	Old	New	Δ%
CPU	1_023_470_754	1_028_574_754	+0.50%
Memory	5_395_058	5_426_958	+0.59%
Term Size	1_700	1_726	+1.53%
Flat Size	1_674	1_699	+1.49%

This comment will get updated when changes are made.

[Unisay]

I don't quite understand:

• Why couldn't we use -00 before.
• How commits in this PR solve the problem.

[bezirg]

I don't quite understand:

• Why couldn't we use -00 before.
• How commits in this PR solve the problem.

There were some compiler options missing on the cabal file.
And there were some GHC -O1 compiler optimisations that happened to fire and make the examples work (e.g. using haskell's div instead of plutus-prelude divide, etc)

[bezirg]

Can somebody accept this? It is not a major change

[Unisay]

The build is failing for me (aarch64-darwin) with errors like this one:

[60 of 66] Compiling ShortCircuit.Spec ( test/ShortCircuit/Spec.hs, /Users/yura/Projects/Cardano/plutus/dist-newstyle/build/aarch64-osx/ghc-9.6.7/plutus-tx-plugin-1.54.0.0/t/plutus-tx-plugin-tests/build/plutus-tx-plugin-tests/plutus-tx-plugin-tests-tmp/ShortCircuit/Spec.o )

<no location info>: error:
    GHC Core to PLC plugin: Error: Reference to a name which is not a local, a builtin, or an external INLINABLE function: Variable PlutusTx.Builtins.error
                               No unfolding

[Unisay]

I tried cabal clean && cabal build all --ghc-option -O0 and it fails.

[bezirg]

I tried cabal clean && cabal build all --ghc-option -O0 and it fails.

It used to work :(

[bezirg]

Actually I give up on it, the unfoldings are not there with -O0 .