WIP on integrating hlint using DAML approach

But getting a mismatch on ghc-lib vs GHC types for the call to hlint.

Closes #32

Author: alanz

Diff for: exe/Main.hs

@@ -101,6 +101,7 @@ import Ide.Plugin.Example                 as Example
 import Ide.Plugin.Example2                as Example2
 import Ide.Plugin.GhcIde                  as GhcIde
 import Ide.Plugin.Floskell                as Floskell
+import Ide.Plugin.Hlint                   as Hlint
 import Ide.Plugin.Ormolu                  as Ormolu
 import Ide.Plugin.StylishHaskell          as StylishHaskell
 #if AGPL
@@ -141,8 +142,9 @@ idePlugins includeExamples = pluginDescToIdePlugins allPlugins
       , Ormolu.descriptor   "ormolu"
       , StylishHaskell.descriptor "stylish-haskell"
 #if AGPL
-      , Brittany.descriptor    "brittany"
+      , Brittany.descriptor "brittany"
 #endif
+      , Hlint.descriptor "hlint"
       ]
     examplePlugins =
       [Example.descriptor  "eg"

Diff for: haskell-language-server.cabal

@@ -77,6 +77,7 @@ library
     , gitrev
     , hashable
     , haskell-lsp == 0.22.*
+    , haskell-src-exts
     , hie-bios >= 0.4
     , hslogger
     , lens
@@ -108,6 +109,53 @@ library
 
   default-language: Haskell2010
 
+flag ghc-lib
+  default: False
+  manual: True
+  description: Force dependency on ghc-lib-parser even if GHC API in the ghc package is supported
+
+library hls-ghc-lib
+  exposed-modules:
+    Ide.Plugin.Hlint
+  hs-source-dirs:
+    src
+  build-depends:
+      base
+    , aeson
+    , binary
+    , bytestring
+    , containers
+    , data-default
+    , deepseq
+    , directory
+    , extra
+    , filepath
+    , ghcide
+    , hashable
+    , haskell-lsp
+    , haskell-src-exts
+    , hlint >= 3.0
+    , regex-tdfa
+    , shake
+    , text
+    , transformers
+    , unordered-containers
+  if !flag(ghc-lib) && impl(ghc >= 8.10.1) && impl(ghc < 8.11.0)
+    build-depends:
+      ghc == 8.10.*
+  else
+    build-depends:
+      ghc-lib == 8.10.*
+
+  ghc-options:
+         -Wall
+         -Wredundant-constraints
+         -Wno-name-shadowing
+  if flag(pedantic)
+     ghc-options:      -Werror
+
+  default-language: Haskell2010
+
 executable haskell-language-server
   import: agpl
   main-is: Main.hs
@@ -162,6 +210,7 @@ executable haskell-language-server
     , haskell-lsp
     , hie-bios >= 0.4
     , haskell-language-server
+    , hls-ghc-lib
     , hslogger
     , optparse-applicative
     , safe-exceptions