From 9a4a5aa77a303c2e56e9dc9bd9327974bf777894 Mon Sep 17 00:00:00 2001
From: Richard Si <sichard26@gmail.com>
Date: Wed, 28 Jun 2023 18:25:43 -0400
Subject: [PATCH] Process NamedTuple decorators in semantic analyzer (#15513)

---
 mypy/semanal.py                        |  4 ++++
 mypyc/test-data/run-tuples.test        |  6 ++++++
 test-data/unit/semanal-namedtuple.test | 20 ++++++++++++++++++++
 3 files changed, 30 insertions(+)

diff --git a/mypy/semanal.py b/mypy/semanal.py
index d18cc4298fed..1eb14e499e4d 100644
--- a/mypy/semanal.py
+++ b/mypy/semanal.py
@@ -1744,6 +1744,10 @@ def analyze_namedtuple_classdef(
                 self.setup_type_vars(defn, tvar_defs)
                 self.setup_alias_type_vars(defn)
                 with self.scope.class_scope(defn.info):
+                    for deco in defn.decorators:
+                        deco.accept(self)
+                        if isinstance(deco, RefExpr) and deco.fullname in FINAL_DECORATOR_NAMES:
+                            info.is_final = True
                     with self.named_tuple_analyzer.save_namedtuple_body(info):
                         self.analyze_class_body_common(defn)
             return True
diff --git a/mypyc/test-data/run-tuples.test b/mypyc/test-data/run-tuples.test
index f6c92b9c720f..0851c15e57fd 100644
--- a/mypyc/test-data/run-tuples.test
+++ b/mypyc/test-data/run-tuples.test
@@ -98,6 +98,7 @@ assert f(Sub(3, 2)) == 3
 -- Ref: https://github.com/mypyc/mypyc/issues/924
 [case testNamedTupleClassSyntax]
 from typing import Dict, List, NamedTuple, Optional, Tuple, Union
+from typing_extensions import final
 
 class FuncIR: pass
 
@@ -121,6 +122,11 @@ class Record(NamedTuple):
 # Ref: https://github.com/mypyc/mypyc/issues/938
 class ClassIR: pass
 
+# Ref: https://github.com/mypyc/mypyc/issues/927
+@final
+class Inextensible(NamedTuple):
+    x: int
+
 [file driver.py]
 from typing import ForwardRef, Optional
 from native import ClassIR, FuncIR, Record
diff --git a/test-data/unit/semanal-namedtuple.test b/test-data/unit/semanal-namedtuple.test
index df1d5679c892..f396f799028f 100644
--- a/test-data/unit/semanal-namedtuple.test
+++ b/test-data/unit/semanal-namedtuple.test
@@ -225,3 +225,23 @@ class B(A): pass
 [out]
 main:2: error: Unsupported dynamic base class "NamedTuple"
 main:2: error: Name "NamedTuple" is not defined
+
+[case testNamedTupleWithDecorator]
+from typing import final, NamedTuple
+
+@final
+class A(NamedTuple("N", [("x", int)])):
+    pass
+[builtins fixtures/tuple.pyi]
+[out]
+MypyFile:1(
+  ImportFrom:1(typing, [final, NamedTuple])
+  ClassDef:4(
+    A
+    TupleType(
+      Tuple[builtins.int, fallback=__main__.N@4])
+    Decorators(
+      NameExpr(final [typing.final]))
+    BaseType(
+      __main__.N@4)
+    PassStmt:5()))