Normalize flags/ghc-options across packages

[ChrisPenner]

Looking through all the package.yamls and our optimization flags are all over the place;

• Some packages have an optimize flag, half of these default to "on", half off
• Some packages set -O0 in ghc-options, but then immediately set -O2 using the optimize flag which defaults to on, making the original -O0 completely redundant since I can't find anywhere that we manually disable the optimize flag other than running with stack build --fast, where the -O0 is redundant anyways.
• some packages don't set any optimization flags at all, according to this doc the default if unset is -O1
• We then use $locals in stack.yaml to provide new settings for a lot of flags anyways, so a lot of local ghc-options will be overridden 🤔 , but we don't provide an override for -O

ghc-options:
 # All packages
 "$locals": -Wall -Werror -Wno-name-shadowing -Wno-missing-pattern-synonym-signatures -fprint-expanded-synonyms -fwrite-ide-info #-freverse-errors

We should decide how we want to arrange this and make everything consistent, I'm pretty confident we're not building with all the desired flags all the time, and things get more complex when we depend on these packages from Enlil because we can't override flags using $locals since unison isn't considered local in this case (I think, documentation for this sort of behaviour is scant at best).

Goals:

• It's easy to run a non-optimized build of unison-cli for contributors
• It's easy to build an optimized build (where all packages are optimized) for releases
• It's easy for Share to ensure its unison dependencies are optimized when building for releases
• The result isn't a confusing mess 😋

[philderbeast]

I'm the maintainer of hpack-dhall and this tool (a lightweight dhall layer on top of hpack) could help here as it makes it very easy to import common items you might want in every (or some) generated .cabal file like ghc-options. If the imported item is a list you can append items and if a record then fields can be picked off or merged with another record.

It would be a bit of leg work converting package.yaml to package.dhall as there are 26 of them but if you have a set of 2 or 3 that you'd like me to convert as a proof of concept then I'd be willing to do that.

$ tree --prune -P '*.cabal'
.
├── codebase2
│   ├── codebase
│   │   └── unison-codebase.cabal
│   ├── codebase-sqlite
│   │   └── unison-codebase-sqlite.cabal
│   ├── codebase-sqlite-hashing-v2
│   │   └── unison-codebase-sqlite-hashing-v2.cabal
│   ├── codebase-sync
│   │   └── unison-codebase-sync.cabal
│   ├── core
│   │   └── unison-core.cabal
│   ├── util-serialization
│   │   └── unison-util-serialization.cabal
│   └── util-term
│       └── unison-util-term.cabal
├── lib
│   ├── unison-hash
│   │   └── unison-hash.cabal
│   ├── unison-hashing
│   │   └── unison-hashing.cabal
│   ├── unison-hash-orphans-aeson
│   │   └── unison-hash-orphans-aeson.cabal
│   ├── unison-hash-orphans-sqlite
│   │   └── unison-hash-orphans-sqlite.cabal
│   ├── unison-prelude
│   │   └── unison-prelude.cabal
│   ├── unison-pretty-printer
│   │   └── unison-pretty-printer.cabal
│   ├── unison-sqlite
│   │   └── unison-sqlite.cabal
│   ├── unison-util-base32hex
│   │   └── unison-util-base32hex.cabal
│   ├── unison-util-bytes
│   │   └── unison-util-bytes.cabal
│   ├── unison-util-cache
│   │   └── unison-util-cache.cabal
│   ├── unison-util-relation
│   │   └── unison-util-relation.cabal
│   └── unison-util-rope
│       └── unison-util-rope.cabal
├── parser-typechecker
│   └── unison-parser-typechecker.cabal
├── unison-cli
│   └── unison-cli.cabal
├── unison-core
│   └── unison-core1.cabal
├── unison-hashing-v2
│   └── unison-hashing-v2.cabal
├── unison-share-api
│   └── unison-share-api.cabal
├── unison-syntax
│   └── unison-syntax.cabal
└── yaks
    └── easytest
        └── easytest.cabal

29 directories, 26 files