Cabal跨开发者配置：统一with-compiler与extra-lib-dirs方案问询

Handling with-compiler Without Absolute Paths #

1. Use version-based compiler references with a GHC manager
   If all developers use a GHC version manager like GHCup, specify the required GHC version in your tracked cabal.project file instead of an absolute path:

   with-compiler: ghc-9.6.4
   

   As long as each developer has that version installed, the ghc-<version> executable will be in their system PATH, so Cabal will find it automatically without needing a hardcoded path.

2. Provide a template for cabal.project.local
   Since cabal.project.local isn't tracked in Git, create a tracked cabal.project.local.example file with clear instructions:

   # Copy this file to cabal.project.local and update the path to your GHC executable
   with-compiler: /path/to/your/ghc/exe
   

   Tell other developers to copy this template and adjust the path to their local GHC installation.

Fixing extra-lib-dirs Relative Path Issues #

Cabal supports relative paths for extra-lib-dirs (resolved relative to the cabal.project file's directory). Try these fixes:

1. Explicitly use a project-root-relative path
   Update your cabal.project to use ./ to make the relative path unambiguous:

   extra-lib-dirs: ./libs/mylib
   

   This works if libs/mylib is directly under your project root (where cabal.project resides).

2. Update Cabal to a newer version
   Older Cabal versions (pre-3.0) had issues with relative extra-lib-dirs paths. Ensure everyone uses Cabal 3.0 or later. Check your version with:

   cabal --version
   

3. Wrap the library as a Cabal package (if possible)
   If you control the mylib code, convert it into a proper Cabal package. Add its .cabal file to libs/mylib, then include it in your cabal.project as a local package:

   packages: . ./libs/mylib
   

   This eliminates the need for extra-lib-dirs entirely—Cabal will handle building and linking the library automatically across all systems.

4. Platform-specific path conditionals (if needed)
   If your library has platform-specific binaries, use Cabal's conditional syntax to target different paths:

   if os(windows)
       extra-lib-dirs: ./libs/mylib/windows
   else if os(linux)
       extra-lib-dirs: ./libs/mylib/linux
   else if os(darwin)
       extra-lib-dirs: ./libs/mylib/macos
   

内容的提问来源于stack exchange，提问作者RandomB