Show signature help even when there are type applications

Author: jian-lin

plugins/hls-signature-help-plugin/src/Ide/Plugin/SignatureHelp.hs

@@ -291,19 +291,23 @@ getNodeNameAndTypes hieKind hieAst =
 isUse :: IdentifierDetails a -> Bool
 isUse = identInfo >>> S.member Use
 
+-- TODO(@linj) handle more cases
 -- Just 1 means the first argument
 getArgumentNumber :: RealSrcSpan -> HieAST a -> Maybe Integer
-getArgumentNumber span hieAst =
-    if nodeHasAnnotation ("HsApp", "HsExpr") hieAst
-        then
-            case nodeChildren hieAst of
-                [leftChild, _] ->
-                    if span `isRealSubspanOf` nodeSpan leftChild
-                        then Nothing
-                        else getArgumentNumber span leftChild >>= \argumentNumber -> Just (argumentNumber + 1)
-                _ -> Nothing -- impossible
-        else
-            case nodeChildren hieAst of
-                []      -> Just 0 -- the function is found
-                [child] -> getArgumentNumber span child -- ignore irrelevant nodes
-                _       -> Nothing -- TODO(@linj) handle more cases such as `if`
+getArgumentNumber span hieAst
+    | nodeHasAnnotation ("HsApp", "HsExpr") hieAst =
+          case nodeChildren hieAst of
+              [leftChild, _] ->
+                  if span `isRealSubspanOf` nodeSpan leftChild
+                      then Nothing
+                      else getArgumentNumber span leftChild >>= \argumentNumber -> Just (argumentNumber + 1)
+              _ -> Nothing -- impossible
+    | nodeHasAnnotation ("HsAppType", "HsExpr") hieAst =
+          case nodeChildren hieAst of
+              [leftChild, _] -> getArgumentNumber span leftChild
+              _              -> Nothing -- impossible
+    | otherwise =
+          case nodeChildren hieAst of
+              []      -> Just 0 -- the function is found
+              [child] -> getArgumentNumber span child -- ignore irrelevant nodes
+              _       -> Nothing

plugins/hls-signature-help-plugin/test/Main.hs

@@ -336,6 +336,19 @@ main =
                   |]
                   [ Nothing,
                     Just $ SignatureHelp [SignatureInformation "mkBytes :: ForeignPtr Word8 -> Word -> Word -> Bytes" (Just $ InR $ MarkupContent MarkupKind_Markdown "\n\nCreate a Bytes datatype representing raw bytes to be embedded into the\n program/library binary.\n\n\\[Documentation\\]\\(file://.*\\)\n\n\\[Source\\]\\(file://.*\\)\n\n") (Just [ParameterInformation (InR (11,27)) (Just $ InR $ MarkupContent MarkupKind_Markdown "\n\nPointer to the data\n\n"), ParameterInformation (InR (31,35)) (Just $ InR $ MarkupContent MarkupKind_Markdown "\n\nOffset from the pointer\n\n"), ParameterInformation (InR (39,43)) (Just $ InR $ MarkupContent MarkupKind_Markdown "\n\nNumber of bytes\n\n")]) (Just (InL 0))] (Just 0) (Just (InL 0))
+                  ],
+              mkTest
+                  "TypeApplications"
+                  [trimming|
+                      f :: a -> b -> c
+                      f = _
+                      x = f @Int @_ 1 True
+                          ^  ^    ^ ^
+                  |]
+                  [ Nothing,
+                    Nothing,
+                    Nothing,
+                    Just $ SignatureHelp [SignatureInformation "f :: forall a b c. a -> b -> c" Nothing (Just [ParameterInformation (InR (19,20)) Nothing, ParameterInformation (InR (24,25)) Nothing]) (Just (InL 0))] (Just 0) (Just (InL 0))
                   ]
             ]