Validate fragment spread target existence

src/Language/GraphQL/AST/Document.hs

@@ -163,7 +163,7 @@ type SelectionSetOpt = [Selection]
 -- @
 data Selection
     = Field (Maybe Alias) Name [Argument] [Directive] SelectionSetOpt
-    | FragmentSpread Name [Directive]
+    | FragmentSpread Name [Directive] Location
     | InlineFragment (Maybe TypeCondition) [Directive] SelectionSet
     deriving (Eq, Show)
 

src/Language/GraphQL/AST/Encoder.hs

@@ -130,7 +130,7 @@ selection formatter = Lazy.Text.append indent' . encodeSelection
         field incrementIndent alias name args directives' selections
     encodeSelection (InlineFragment typeCondition directives' selections) =
         inlineFragment incrementIndent typeCondition directives' selections
-    encodeSelection (FragmentSpread name directives') =
+    encodeSelection (FragmentSpread name directives' _) =
         fragmentSpread incrementIndent name directives'
     incrementIndent
         | Pretty indentation <- formatter = Pretty $ indentation + 1

src/Language/GraphQL/AST/Parser.hs

@@ -400,11 +400,12 @@ argument :: Parser Argument
 argument = Argument <$> name <* colon <*> value <?> "Argument"
 
 fragmentSpread :: Parser Selection
-fragmentSpread = FragmentSpread
-    <$ spread
-    <*> fragmentName
-    <*> directives
-    <?> "FragmentSpread"
+fragmentSpread = label "FragmentSpread" $ do
+    location <- getLocation
+    _ <- spread
+    fragmentName' <- fragmentName
+    directives' <- directives
+    pure $ FragmentSpread fragmentName' directives' location
 
 inlineFragment :: Parser Selection
 inlineFragment = InlineFragment