Add common stanza to completion data

This allows fields and values to be completed correctly inside common
stanzas

Author: VeryMilkyJoe

Diff for: plugins/hls-cabal-plugin/src/Ide/Plugin/Cabal/Completion/Data.hs

@@ -63,7 +63,7 @@ cabalKeywords =
       ("extra-tmp-files:", filePathCompleter)
     ]
 
--- | Map, containing all stanzas in a cabal file as keys
+-- | Map, containing all stanzas in a cabal file as keys,
 --  and lists of their possible nested keywords as values.
 stanzaKeywordMap :: Map StanzaType (Map KeyWordName Completer)
 stanzaKeywordMap =
@@ -73,6 +73,7 @@ stanzaKeywordMap =
       ("test-suite", testSuiteFields <> libExecTestBenchCommons),
       ("benchmark", benchmarkFields <> libExecTestBenchCommons),
       ("foreign-library", foreignLibraryFields <> libExecTestBenchCommons),
+      ("common", libExecTestBenchCommons),
       ("flag", flagFields),
       ("source-repository", sourceRepositoryFields)
     ]

Diff for: plugins/hls-cabal-plugin/test/Completer.hs

@@ -51,6 +51,11 @@ basicCompleterTests =
         compls <- getCompletions doc (Position 8 2)
         let complTexts = getTextEditTexts compls
         liftIO $ assertBool "suggests benchmark" $ "benchmark" `elem` complTexts
+    , runCabalTestCaseSession "In top level context - stanza should be suggested" "" $ do
+        doc <- openDoc "completer.cabal" "cabal"
+        compls <- getCompletions doc (Position 13 2)
+        let complTexts = getTextEditTexts compls
+        liftIO $ assertBool "suggests common" $ "common" `elem` complTexts
     , runCabalTestCaseSession "Main-is completions should be relative to hs-source-dirs of same stanza" "filepath-completions" $ do
         doc <- openDoc "main-is.cabal" "cabal"
         compls <- getCompletions doc (Position 10 12)

Diff for: plugins/hls-cabal-plugin/test/Context.hs

@@ -188,6 +188,9 @@ getContextTests =
             , (Stanza "source-repository" (Just "head"), KeyWord "type:")
             , (Stanza "source-repository" (Just "head"), KeyWord "type:")
             , (Stanza "source-repository" (Just "head"), None)
+            , (Stanza "common" (Just "cabalfmt"), None)
+            , (Stanza "common" (Just "cabalfmt"), None)
+            , (Stanza "common" (Just "cabalfmt"), KeyWord "build-depends:")
             ]
             $ \fileContent posPrefInfo ->
                 callGetContext (cursorPos posPrefInfo) (prefixText posPrefInfo) fileContent
@@ -276,4 +279,10 @@ source-repository head
   location: https://github.com/haskell/haskell-language-server
 
   ^
+common cabalfmt
+
+  ^
+  build-depends: haskell-language-server:hls-cabal-fmt-plugin
+    ^            ^
+  cpp-options: -Dhls_cabalfmt
 |]

Diff for: plugins/hls-cabal-plugin/test/testdata/completer.cabal

@@ -10,3 +10,5 @@ be
 
 library
     lib
+
+co