From 957ae15e3b98e37aef40c28e268950859d992c31 Mon Sep 17 00:00:00 2001
From: johndoe6345789 <john.doe6345789@gmail.com>
Date: Wed, 24 Dec 2025 16:59:02 +0000
Subject: [PATCH] Require annotations for lambda parameters

---
 Python/ast.c | 48 ++++++++++++++++++++++++++++++++++--------------
 1 file changed, 34 insertions(+), 14 deletions(-)

diff --git a/Python/ast.c b/Python/ast.c
index e01dd0d..9f7577e 100644
--- a/Python/ast.c
+++ b/Python/ast.c
@@ -97,12 +97,18 @@ validate_keywords(asdl_keyword_seq *keywords)
 }
 
 static int
-validate_args(asdl_arg_seq *args)
+validate_args(asdl_arg_seq *args, int require_annotations)
 {
     assert(!PyErr_Occurred());
     for (Py_ssize_t i = 0; i < asdl_seq_LEN(args); i++) {
         arg_ty arg = asdl_seq_GET(args, i);
         VALIDATE_POSITIONS(arg);
+        if (require_annotations && arg->annotation == NULL) {
+            PyErr_Format(PyExc_SyntaxError,
+                         "missing type annotation for argument '%U'",
+                         arg->arg);
+            return 0;
+        }
         if (arg->annotation && !validate_expr(arg->annotation, Load))
             return 0;
     }
@@ -125,21 +131,35 @@ expr_context_name(expr_context_ty ctx)
 }
 
 static int
-validate_arguments(arguments_ty args)
+validate_vararg(arg_ty arg, int require_annotations)
+{
+    if (require_annotations && arg->annotation == NULL) {
+        PyErr_Format(PyExc_SyntaxError,
+                     "missing type annotation for argument '%U'",
+                     arg->arg);
+        return 0;
+    }
+    if (arg->annotation && !validate_expr(arg->annotation, Load)) {
+        return 0;
+    }
+    return 1;
+}
+
+static int
+validate_arguments(arguments_ty args, int require_annotations)
 {
     assert(!PyErr_Occurred());
-    if (!validate_args(args->posonlyargs) || !validate_args(args->args)) {
+    if (!validate_args(args->posonlyargs, require_annotations)
+        || !validate_args(args->args, require_annotations)) {
         return 0;
     }
-    if (args->vararg && args->vararg->annotation
-        && !validate_expr(args->vararg->annotation, Load)) {
-            return 0;
-    }
-    if (!validate_args(args->kwonlyargs))
+    if (args->vararg && !validate_vararg(args->vararg, require_annotations)) {
+        return 0;
+    }
+    if (!validate_args(args->kwonlyargs, require_annotations))
+        return 0;
+    if (args->kwarg && !validate_vararg(args->kwarg, require_annotations)) {
         return 0;
-    if (args->kwarg && args->kwarg->annotation
-        && !validate_expr(args->kwarg->annotation, Load)) {
-            return 0;
     }
     if (asdl_seq_LEN(args->defaults) > asdl_seq_LEN(args->posonlyargs) + asdl_seq_LEN(args->args)) {
         PyErr_SetString(PyExc_ValueError, "more positional defaults than args on arguments");
@@ -272,7 +292,7 @@ validate_expr(expr_ty exp, expr_context_ty ctx)
         ret = validate_expr(exp->v.UnaryOp.operand, Load);
         break;
     case Lambda_kind:
-        ret = validate_arguments(exp->v.Lambda.args) &&
+        ret = validate_arguments(exp->v.Lambda.args, 1) &&
             validate_expr(exp->v.Lambda.body, Load);
         break;
     case IfExp_kind:
@@ -734,7 +754,7 @@ validate_stmt(stmt_ty stmt)
     case FunctionDef_kind:
         ret = validate_body(stmt->v.FunctionDef.body, "FunctionDef") &&
             validate_type_params(stmt->v.FunctionDef.type_params) &&
-            validate_arguments(stmt->v.FunctionDef.args) &&
+            validate_arguments(stmt->v.FunctionDef.args, 1) &&
             validate_exprs(stmt->v.FunctionDef.decorator_list, Load, 0) &&
             (!stmt->v.FunctionDef.returns ||
              validate_expr(stmt->v.FunctionDef.returns, Load));
@@ -930,7 +950,7 @@ validate_stmt(stmt_ty stmt)
     case AsyncFunctionDef_kind:
         ret = validate_body(stmt->v.AsyncFunctionDef.body, "AsyncFunctionDef") &&
             validate_type_params(stmt->v.AsyncFunctionDef.type_params) &&
-            validate_arguments(stmt->v.AsyncFunctionDef.args) &&
+            validate_arguments(stmt->v.AsyncFunctionDef.args, 1) &&
             validate_exprs(stmt->v.AsyncFunctionDef.decorator_list, Load, 0) &&
             (!stmt->v.AsyncFunctionDef.returns ||
              validate_expr(stmt->v.AsyncFunctionDef.returns, Load));