Cabal plugin: implement check for package.yaml in a stack project

plugins/hls-cabal-plugin/src/Ide/Plugin/Cabal/CabalAdd.hs

@@ -278,6 +278,9 @@ getDependencyEdit recorder env cabalFilePath buildTarget dependency = do
       pure edit
 
 -- | Given a path to a haskell file, returns the closest cabal file.
+--   If package.yaml is present in same directory as .cabal file, it returns nothing, because adding a dependency to a generated cabal file
+--   will break propagation of changes from package.yaml to cabal file in stack project.
+--
 --   If cabal file wasn't found, gives Nothing.
 findResponsibleCabalFile :: FilePath -> IO (Maybe FilePath)
 findResponsibleCabalFile haskellFilePath = do
@@ -293,7 +296,12 @@ findResponsibleCabalFile haskellFilePath = do
       cabalFiles <- filterM (\c -> doesFileExist c) objectsCabalExtension
       case safeHead cabalFiles of
         Nothing        -> go ps
-        Just cabalFile -> pure $ Just cabalFile
+        Just cabalFile -> guardAgainstHpack path cabalFile
+          where
+            guardAgainstHpack :: FilePath -> FilePath -> IO (Maybe FilePath)
+            guardAgainstHpack path cabalFile = do
+              exists <- doesFileExist $ path </> "package.yaml"
+              if exists then pure Nothing else pure $ Just cabalFile
 
 -- | Gives cabal file's contents or throws error.
 --   Inspired by @readCabalFile@ in cabal-add,

plugins/hls-cabal-plugin/test/CabalAdd.hs

@@ -29,6 +29,8 @@ cabalAddTests =
     "CabalAdd Tests"
     [ runHaskellTestCaseSession "Code Actions - Can add hidden package" ("cabal-add-testdata" </> "cabal-add-exe")
         (generateAddDependencyTestSession "cabal-add-exe.cabal" ("src" </> "Main.hs") "split" [253])
+    , runHaskellTestCaseSession "Code Actions - Guard against HPack" ("cabal-add-testdata" </> "cabal-add-packageYaml")
+        (generatePackageYAMLTestSession ("src" </> "Main.hs"))
     , runHaskellTestCaseSession "Code Actions - Can add hidden package to a library" ("cabal-add-testdata" </> "cabal-add-lib")
         (generateAddDependencyTestSession "cabal-add-lib.cabal" ("src" </> "MyLib.hs") "split" [348])
     , runHaskellTestCaseSession "Code Actions - Can add hidden package to a test" ("cabal-add-testdata" </> "cabal-add-tests")
@@ -139,3 +141,12 @@ cabalAddTests =
           , _codeDescription = Nothing
           , _data_ = Nothing
         }
+
+
+    generatePackageYAMLTestSession :: FilePath -> Session ()
+    generatePackageYAMLTestSession haskellFile  = do
+        hsdoc <- openDoc haskellFile "haskell"
+        _ <- waitForDiagnosticsFrom hsdoc
+        cas <- Maybe.mapMaybe (^? _R) <$> getAllCodeActions hsdoc
+        let selectedCas = filter (\ca -> "Add dependency" `T.isPrefixOf` (ca ^. L.title)) cas
+        liftIO $ assertEqual "PackageYAML" [] selectedCas

plugins/hls-cabal-plugin/test/testdata/cabal-add-testdata/cabal-add-packageYaml/cabal-add-bench.cabal

@@ -0,0 +1,17 @@
+cabal-version:      2.4
+name:               cabal-add-bench
+version:            0.1.0.0
+license:            NONE
+author:             George Gerasev
+maintainer:         [email protected]
+build-type:         Simple
+
+common warnings
+    ghc-options: -Wall
+
+benchmark benchmark
+    type: exitcode-stdio-1.0
+    ghc-options: -threaded
+    main-is: Main.hs
+    hs-source-dirs: bench
+    build-depends: base

plugins/hls-cabal-plugin/test/testdata/cabal-add-testdata/cabal-add-packageYaml/src/Main.hs

@@ -0,0 +1,6 @@
+module Main (main) where
+
+import Data.List.Split
+
+main :: IO ()
+main = putStrLn "Test suite not yet implemented."

plugins/hls-cabal-plugin/test/testdata/cabal-add-testdata/cabal.project

@@ -2,3 +2,4 @@ packages: cabal-add-exe
           cabal-add-lib
           cabal-add-tests
           cabal-add-bench
+          cabal-add-packageYaml