Add pedantic flag and remove cabal.project

.github/workflows/ci.yaml

@@ -31,6 +31,7 @@ jobs:
         with:
           ghc-version: ${{ matrix.ghc }}
           cabal-version: ${{ matrix.cabal }}
+      - run: cabal configure --enable-tests --flags pedantic --jobs
       - run: cabal freeze && cat cabal.project.freeze
       - uses: actions/cache@v2
         with:

.gitignore

@@ -2,6 +2,7 @@
 /.ghc.environment*
 /.stack-work/
 /cabal.project.freeze
+/cabal.project.local*
 /cabal.sandbox.config
 /dist-newstyle/
 /dist/

cabal.project

@@ -1,6 +0,0 @@
-jobs: $ncpus
-packages: .
-
-package witch
-  ghc-options: -Werror
-  tests: True

witch.cabal

@@ -16,6 +16,11 @@ source-repository head
   location: https://github.com/tfausak/witch
   type: git
 
+flag pedantic
+  default: False
+  description: Enables @-Werror@, which turns warnings into errors.
+  manual: True
+
 common basics
   build-depends:
     , base >= 4.10.0 && < 4.17
@@ -51,6 +56,10 @@ common basics
     ghc-options:
       -Wno-missing-kind-signatures
 
+  if flag(pedantic)
+    ghc-options:
+      -Werror
+
 library
   import: basics