From b6e91d46b299bfd0af36b37586d3337a20e14b0e Mon Sep 17 00:00:00 2001
From: Ali Hamdan <ali.hamdan.dev@gmail.com>
Date: Sun, 11 Feb 2024 23:09:22 +0100
Subject: [PATCH] stubgen: Preserve empty tuple annotation (#16907)

---
 mypy/stubutil.py            |  2 ++
 test-data/unit/stubgen.test | 14 ++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/mypy/stubutil.py b/mypy/stubutil.py
index 1a9c2357c58e..69af643efab2 100644
--- a/mypy/stubutil.py
+++ b/mypy/stubutil.py
@@ -250,6 +250,8 @@ def visit_unbound_type(self, t: UnboundType) -> str:
             self.stubgen.import_tracker.require_name(s)
         if t.args:
             s += f"[{self.args_str(t.args)}]"
+        elif t.empty_tuple_index:
+            s += "[()]"
         return s
 
     def visit_none_type(self, t: NoneType) -> str:
diff --git a/test-data/unit/stubgen.test b/test-data/unit/stubgen.test
index b5bccaa4cdbd..c56f6b40b74d 100644
--- a/test-data/unit/stubgen.test
+++ b/test-data/unit/stubgen.test
@@ -4253,3 +4253,17 @@ def f5(x: int, /, *, y: float): ...
 def f6(x: int = 0, /, *, y: float): ...
 def f7(x: int, /, *, y: float = 1): ...
 def f8(x: int = 0, /, *, y: float = 1): ...
+
+[case testPreserveEmptyTuple]
+ann: tuple[()]
+alias = tuple[()]
+def f(x: tuple[()]): ...
+class C(tuple[()]): ...
+
+[out]
+ann: tuple[()]
+alias = tuple[()]
+
+def f(x: tuple[()]): ...
+
+class C(tuple[()]): ...