From 7b37f1c0e01f07191ba268005948653a0b3af7a6 Mon Sep 17 00:00:00 2001
From: Till Ehrengruber <till.ehrengruber@cscs.ch>
Date: Sun, 1 Dec 2024 20:55:42 +0100
Subject: [PATCH] Fix type synthesizer for partially typed arithmetic ops

---
 src/gt4py/next/iterator/type_system/type_synthesizer.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/gt4py/next/iterator/type_system/type_synthesizer.py b/src/gt4py/next/iterator/type_system/type_synthesizer.py
index 5be9ed7438..5fc78a7c6f 100644
--- a/src/gt4py/next/iterator/type_system/type_synthesizer.py
+++ b/src/gt4py/next/iterator/type_system/type_synthesizer.py
@@ -94,6 +94,10 @@ def power(base: ts.ScalarType, exponent: ts.ScalarType) -> ts.ScalarType:
 
 @_register_builtin_type_synthesizer(fun_names=itir.BINARY_MATH_NUMBER_BUILTINS)
 def _(lhs: ts.ScalarType, rhs: ts.ScalarType) -> ts.ScalarType:
+    if isinstance(lhs, ts.DeferredType):
+        return rhs
+    if isinstance(rhs, ts.DeferredType):
+        return lhs
     assert lhs == rhs
     return lhs