hls-class-plugin: Find methods even inside an EvidenceVarBind

plugins/hls-class-plugin/src/Ide/Plugin/Class.hs

@@ -262,13 +262,29 @@ codeAction recorder state plId (CodeActionParams _ _ docId _ context) = liftIO $
             $ pointCommand hf (instanceRange ^. J.start & J.character -~ 1)
             $ map (T.pack . getOccString) . rights . findInstanceValBindIdentifiers
 
+    -- | Recurses through the given AST to find identifiers which are are
+    -- 'InstanceValBind's. Two types of nodes are chosen to look inside:
+    --
+    -- 1. The nodes which don't have any identifiers: these are the nodes which
+    -- somehow wrap an expression, like the instance declaration itself, or a
+    -- 'Match' which contains the 'InstanceValBind'.
+    --
+    -- 2. The nodes which have an 'EvidenceVarBind': if one of the implemented
+    -- methods uses functions like 'undefined', the binding for the '?callstack'
+    -- gets bound over the 'Match' which contains the 'InstanceValBind', so to
+    -- find the 'InstanceValBind' this function must look inside any
+    -- 'EvidenceVarBind's it finds.
     findInstanceValBindIdentifiers :: HieAST a -> [Identifier]
     findInstanceValBindIdentifiers ast
-      | Map.null (getNodeIds ast) = concatMap findInstanceValBindIdentifiers (nodeChildren ast)
+      | Map.null nodeIds
+        || hasEvidenceBind nodeIds = concatMap findInstanceValBindIdentifiers (nodeChildren ast)
       | otherwise = Map.keys
                   . Map.filter (not . Set.null)
                   . Map.map (Set.filter isInstanceValBind . identInfo)
-                  $ getNodeIds ast
+                  $ nodeIds
+      where
+          nodeIds = getNodeIds ast
+          hasEvidenceBind = not . Map.null . Map.filter (any isEvidenceBind . identInfo)
 
 ghostSpan :: RealSrcSpan
 ghostSpan = realSrcLocSpan $ mkRealSrcLoc (fsLit "<haskell-language-sever>") 1 1

plugins/hls-class-plugin/test/testdata/T6.1.expected.hs

@@ -11,9 +11,12 @@ class Test a where
   h :: a -> a
   h = f
 
-  {-# MINIMAL f, g | g, h #-}
+  i :: a
+
+  {-# MINIMAL f, g, i | g, h #-}
 
 instance Test X where
   f X = X
   f Y = Y
+  i = undefined
   g = _

plugins/hls-class-plugin/test/testdata/T6.2.expected.hs

@@ -11,10 +11,13 @@ class Test a where
   h :: a -> a
   h = f
 
-  {-# MINIMAL f, g | g, h #-}
+  i :: a
+
+  {-# MINIMAL f, g, i | g, h #-}
 
 instance Test X where
   f X = X
   f Y = Y
+  i = undefined
   g = _
   h = _

plugins/hls-class-plugin/test/testdata/T6.hs

@@ -11,8 +11,11 @@ class Test a where
   h :: a -> a
   h = f
 
-  {-# MINIMAL f, g | g, h #-}
+  i :: a
+
+  {-# MINIMAL f, g, i | g, h #-}
 
 instance Test X where
   f X = X
   f Y = Y
+  i = undefined