fix negative integer parsing in Enum8 and Enum16 types (#295)

* fix negative integer parsing in Enum8 and Enum16 types

* add pr to changelog

Author: ruslandoga

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## Unreleased
+
+- fix negative integer parsing in Enum8 and Enum16 types https://github.com/plausible/ch/pull/295
+
 ## 0.7.0 (2026-01-13)
 
 - use `disconnect_and_retry` (added in DBConnection v2.9.0) instead of `disconnect` for connection errors https://github.com/plausible/ch/pull/292

lib/ch/types.ex

@@ -546,19 +546,20 @@ defmodule Ch.Types do
   end
 
   defp decode_int(<<?-, i, rest::bytes>>, stack, outer_acc) when is_numeric(i) do
-    decode_int_cont(rest, -(i - ?0), stack, outer_acc)
+    decode_int_cont(rest, i - ?0, -1, stack, outer_acc)
   end
 
   defp decode_int(<<i, rest::bytes>>, stack, outer_acc) when is_numeric(i) do
-    decode_int_cont(rest, i - ?0, stack, outer_acc)
+    decode_int_cont(rest, i - ?0, 1, stack, outer_acc)
   end
 
-  defp decode_int_cont(<<i, rest::bytes>>, acc, stack, outer_acc) when is_numeric(i) do
-    decode_int_cont(rest, acc * 10 + i - ?0, stack, outer_acc)
+  defp decode_int_cont(<<i, rest::bytes>>, acc, multiplier, stack, outer_acc)
+       when is_numeric(i) do
+    decode_int_cont(rest, acc * 10 + i - ?0, multiplier, stack, outer_acc)
   end
 
-  defp decode_int_cont(<<rest::bytes>>, int, stack, acc) do
-    decode(stack, rest, [int | acc])
+  defp decode_int_cont(<<rest::bytes>>, int, multiplier, stack, acc) do
+    decode(stack, rest, [int * multiplier | acc])
   end
 
   @doc """

test/ch/types_test.exs

@@ -158,6 +158,12 @@ defmodule Ch.TypesTest do
 
       assert decode(" Enum8 ( 'hello' = 1 , 'world' = 2 ) ") ==
                {:enum8, [{"hello", 1}, {"world", 2}]}
+
+      assert decode("Enum8('enum8_min' = -128, 'enum8_zero' = 0, 'enum8_max' = 127)") ==
+               {:enum8, [{"enum8_min", -128}, {"enum8_zero", 0}, {"enum8_max", 127}]}
+
+      assert decode("Enum16('enum16_min' = -32768, 'enum16_zero' = 0, 'enum16_max' = 32767)") ==
+               {:enum16, [{"enum16_min", -32768}, {"enum16_zero", 0}, {"enum16_max", 32767}]}
     end
 
     test "simple aggregate function" do