Use lowercase tuple where possible (#6170)

tests/check_new_syntax.py

@@ -14,6 +14,9 @@ def check_new_syntax(tree: ast.AST, path: Path) -> list[str]:
             return ast.unparse(node)[1:-1]
         return ast.unparse(node)
 
+    def is_dotdotdot(node: ast.AST) -> bool:
+        return isinstance(node, ast.Constant) and node.s is Ellipsis
+
     class OldSyntaxFinder(ast.NodeVisitor):
         def visit_Subscript(self, node: ast.Subscript) -> None:
             if isinstance(node.value, ast.Name):
@@ -29,6 +32,14 @@ def check_new_syntax(tree: ast.AST, path: Path) -> list[str]:
                 if node.value.id == "Dict":
                     new_syntax = f"dict[{unparse_without_tuple_parens(node.slice)}]"
                     errors.append(f"{path}:{node.lineno}: Use built-in generics, e.g. `{new_syntax}`")
+                # Tuple[Foo, ...] must be allowed because of mypy bugs
+                if node.value.id == "Tuple" and not (
+                    isinstance(node.slice, ast.Tuple)
+                    and len(node.slice.elts) == 2
+                    and is_dotdotdot(node.slice.elts[1])
+                ):
+                    new_syntax = f"tuple[{unparse_without_tuple_parens(node.slice)}]"
+                    errors.append(f"{path}:{node.lineno}: Use built-in generics, e.g. `{new_syntax}`")
 
             self.generic_visit(node)