fix: fix memory leak for recursive structs

Previously we did not delete the pointers of children of recursive
structs, only their immediate member pointers. This commit fixes that
issue.

Note that this is currently handled as a special case and should be made
general.

Author: scolsen

src/Concretize.hs

@@ -902,8 +902,10 @@ concreteDeleteTakePtr typeEnv env members =
 -- | Generate the C code for deleting a single member of the deftype.
 -- | TODO: Should return an Either since this can fail!
 memberDeletionGeneral :: String -> TypeEnv -> Env -> (String, Ty) -> String
-memberDeletionGeneral separator _ _ (memberName, (RecTy _)) =
-  "    " ++ "CARP_FREE(p" ++ separator ++ memberName ++ ");"
+memberDeletionGeneral separator _ _ (memberName, (RecTy t)) =
+  "    if(p"++ separator ++ memberName ++") {" ++ recur ++ "CARP_FREE(p" ++ separator ++ memberName ++ "); p" ++ separator ++ memberName ++ "= NULL;}"
+  -- TODO: Brittle. Come up with a better solution.
+  where recur = tyToC t ++ "_delete(*p" ++ separator ++ memberName ++ "); "
 memberDeletionGeneral separator typeEnv env (memberName, memberType) =
   case findFunctionForMember typeEnv env "delete" (typesDeleterFunctionType memberType) (memberName, memberType) of
     FunctionFound functionFullName -> "    " ++ functionFullName ++ "(p" ++ separator ++ memberName ++ ");"

src/Managed.hs

@@ -17,7 +17,5 @@ isManaged _ _ StringTy =
   True
 isManaged _ _ PatternTy =
   True
-isManaged _ _ (RecTy _) =
-  True
 isManaged _ _ _ =
   False