Make check recognise TypeAbstractions

See haskell#9496.

“Backport” of haskell#9502, notice that we are not adding a new constructor,
just tweaking `check` behaviour.  This is improve UX without breaking
changes.

Author: ffaf1

Cabal/src/Distribution/PackageDescription/Check.hs

@@ -1193,9 +1193,10 @@ checkFields pkg =
     unknownCompilers  = [ name | (OtherCompiler name, _) <- testedWith pkg ]
     unknownLanguages  = [ name | bi <- allBuildInfo pkg
                                , UnknownLanguage name <- allLanguages bi ]
-    unknownExtensions = [ name | bi <- allBuildInfo pkg
-                               , UnknownExtension name <- allExtensions bi
-                               , name `notElem` map prettyShow knownLanguages ]
+    unknownExtensions = filter (/= "TypeAbstractions")
+                          [ name | bi <- allBuildInfo pkg
+                                 , UnknownExtension name <- allExtensions bi
+                                 , name `notElem` map prettyShow knownLanguages ]
     ourDeprecatedExtensions = nub $ catMaybes
       [ find ((==ext) . fst) deprecatedExtensions
       | bi <- allBuildInfo pkg

cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/KnownTypeAbstractions/cabal.out

@@ -0,0 +1,2 @@
+# cabal check
+No errors or warnings could be found in the package.

cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/KnownTypeAbstractions/cabal.test.hs

@@ -0,0 +1,5 @@
+import Test.Cabal.Prelude
+
+-- Uknown extension, exception for TypeAbstractions, see #9496
+main = cabalTest $
+  cabal "check" []

cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/KnownTypeAbstractions/pkg.cabal

@@ -0,0 +1,13 @@
+cabal-version: 3.0
+name: pkg
+synopsis: synopsis
+description: description
+version: 0
+category: example
+maintainer: none@example.com
+license: GPL-3.0-or-later
+
+library
+  exposed-modules: Module
+  default-language: Haskell2010
+  default-extensions: TypeAbstractions

changelog.d/pr-9503

@@ -0,0 +1,11 @@
+synopsis: Make `check` recognise `TypeAbstractions`
+packages: cabal-install
+prs: #9503
+issues: #9496
+
+description: {
+
+- `cabal check` will not complain about “Unknown extension” when
+  finding `TypeAbstractions`.
+
+}

editors/vim/syntax/cabal.vim

@@ -267,6 +267,7 @@ syn keyword cabalExtension contained
   \ TraditionalRecordSyntax
   \ TransformListComp
   \ TupleSections
+  \ TypeAbstractions
   \ TypeApplications
   \ TypeData
   \ TypeFamilies
@@ -405,6 +406,7 @@ syn keyword cabalExtension contained
   \ NoTraditionalRecordSyntax
   \ NoTransformListComp
   \ NoTupleSections
+  \ NoTypeAbstractions
   \ NoTypeApplications
   \ NoTypeFamilies
   \ NoTypeFamilyDependencies