From cd78ce48886ada99bfa5d34a7bf46f2d6ab4c346 Mon Sep 17 00:00:00 2001
From: Phil Tillet <phil@openai.com>
Date: Fri, 29 Apr 2022 09:17:54 -0700
Subject: [PATCH] [FRONTEND] Improved error message when assigning None to
 non-constexpr

---
 python/triton/code_gen.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/python/triton/code_gen.py b/python/triton/code_gen.py
index 711cc87ac..52f9a5a60 100644
--- a/python/triton/code_gen.py
+++ b/python/triton/code_gen.py
@@ -358,6 +358,8 @@ class CodeGenerator(ast.NodeVisitor):
             # by default, constexpr are assigned into python variable
             if isinstance(value, triton.language.constexpr):
                 value = value.value
+            if value is None:
+                raise ValueError(f'Cannot assign None to non-constexpr `{name}`. Please annotate as `: tl.constexpr`')
             if not isinstance(value, triton.language.tensor):
                 value = triton.language.core._to_tensor(value, self.builder)
             self.value_constructor.set_value(name, value)
@@ -719,7 +721,7 @@ class CodeGenerator(ast.NodeVisitor):
         ast.NodeVisitor.generic_visit(self, node)
 
     def visit_NoneType(self, node):
-        return None
+        return triton.language.constexpr(None)
 
     def visit(self, node):
         if node is not None: