gh-145868: Suggest names on typos in __future__ imports

Include/cpython/compile.h

@@ -44,6 +44,7 @@ typedef struct {
 #define FUTURE_BARRY_AS_BDFL "barry_as_FLUFL"
 #define FUTURE_GENERATOR_STOP "generator_stop"
 #define FUTURE_ANNOTATIONS "annotations"
+#define FUTURE_BRACES "braces"
 
 #define PY_INVALID_STACK_EFFECT INT_MAX
 PyAPI_FUNC(int) PyCompile_OpcodeStackEffect(int opcode, int oparg);

Lib/test/test_future_stmt/test_future.py

@@ -3,7 +3,7 @@
 import __future__
 import ast
 import unittest
-from test.support import force_not_colorized, import_helper
+from test.support import force_not_colorized, import_helper, subTests
 from test.support.script_helper import spawn_python, kill_python
 from textwrap import dedent
 import os
@@ -87,8 +87,45 @@ def test_unknown_future_flag(self):
             from __future__ import rested_snopes  # typo error here: nested => rested
         """
         self.assertSyntaxError(
-            code, lineno=2,
-            message='future feature rested_snopes is not defined', offset=24,
+            code,
+            lineno=2,
+            message=(
+                "future feature 'rested_snopes' is not defined. "
+                "Did you mean: 'nested_scopes'?"
+            ),
+            offset=24,
+        )
+
+    @subTests("typo, origin", [
+        ("nest_scopes", "nested_scopes"),
+        ("gneretors", "generators"),
+        ("divicion", "division"),
+        ("absolute_imports", "absolute_import"),
+        ("print_func", "print_function"),
+        ("unicode_literal", "unicode_literals"),
+        ("barry_as_bdfl", "barry_as_FLUFL"),
+        ("generatorstop", "generator_stop"),
+        ("anotations", "annotations"),
+        ("brces", "braces"),
+        ("brace", "braces"),
+    ])
+    def test_typos_in_future_imports(self, typo, origin):
+        self.assertSyntaxError(
+            f"from __future__ import {typo}",
+            lineno=1,
+            message=(
+                f"future feature '{typo}' is not defined. "
+                f"Did you mean: '{origin}'?"
+            ),
+            offset=24,
+        )
+
+    def test_no_suggestion_on_missing_name(self):
+        self.assertSyntaxError(
+            "from __future__ import missing_name",
+            lineno=1,
+            message="future feature 'missing_name' is not defined",
+            offset=24,
         )
 
     def test_future_import_not_on_top(self):
@@ -137,7 +174,7 @@ def test_future_import_star(self):
         code = """
             from __future__ import *
         """
-        self.assertSyntaxError(code, message='future feature * is not defined', offset=24)
+        self.assertSyntaxError(code, message="future feature '*' is not defined", offset=24)
 
     def test_future_import_braces(self):
         code = """

Misc/NEWS.d/next/Core_and_Builtins/2026-07-21-14-38-49.gh-issue-145868.7iGRvU.rst

@@ -0,0 +1,2 @@
+Calculate suggestions during :exc:`SyntaxError` on typos when importing
+names from :mod:`__future__`.

Python/future.c

@@ -1,9 +1,10 @@
 #include "Python.h"
 #include "pycore_ast.h"           // _PyAST_GetDocString()
+#include "pycore_pyerrors.h"      // _Py_CalculateSuggestions()
 #include "pycore_symtable.h"      // _PyFutureFeatures
 #include "pycore_unicodeobject.h" // _PyUnicode_EqualToASCIIString()
 
-#define UNDEFINED_FUTURE_FEATURE "future feature %.100s is not defined"
+#define UNDEFINED_FUTURE_FEATURE "future feature '%.100s' is not defined"
 
 static int
 future_check_features(_PyFutureFeatures *ff, stmt_ty s, PyObject *filename)
@@ -38,7 +39,7 @@ future_check_features(_PyFutureFeatures *ff, stmt_ty s, PyObject *filename)
             continue;
         } else if (strcmp(feature, FUTURE_ANNOTATIONS) == 0) {
             ff->ff_features |= CO_FUTURE_ANNOTATIONS;
-        } else if (strcmp(feature, "braces") == 0) {
+        } else if (strcmp(feature, FUTURE_BRACES) == 0) {
             PyErr_SetString(PyExc_SyntaxError,
                             "not a chance");
             PyErr_RangedSyntaxLocationObject(filename,
@@ -48,8 +49,36 @@ future_check_features(_PyFutureFeatures *ff, stmt_ty s, PyObject *filename)
                                              name->end_col_offset + 1);
             return 0;
         } else {
-            PyErr_Format(PyExc_SyntaxError,
-                         UNDEFINED_FUTURE_FEATURE, feature);
+            PyObject *suggestion;
+            PyObject *future_features = Py_BuildValue("[sssssssssss]",
+                                                      FUTURE_NESTED_SCOPES,
+                                                      FUTURE_GENERATORS,
+                                                      FUTURE_DIVISION,
+                                                      FUTURE_ABSOLUTE_IMPORT,
+                                                      FUTURE_WITH_STATEMENT,
+                                                      FUTURE_PRINT_FUNCTION,
+                                                      FUTURE_UNICODE_LITERALS,
+                                                      FUTURE_BARRY_AS_BDFL,
+                                                      FUTURE_GENERATOR_STOP,
+                                                      FUTURE_ANNOTATIONS,
+                                                      FUTURE_BRACES);
+            if (
+                future_features != NULL &&
+                (suggestion = _Py_CalculateSuggestions(future_features, name->name)) != NULL
+            ) {
+                PyErr_Format(PyExc_SyntaxError,
+                             UNDEFINED_FUTURE_FEATURE ". Did you mean: %R?",
+                             feature, suggestion);
+                Py_DECREF(suggestion);
+            }
+            else {
+                // Do not fail on missing suggestion,
+                // just show the default message.
+                PyErr_Format(PyExc_SyntaxError,
+                             UNDEFINED_FUTURE_FEATURE,
+                             feature);
+            }
+            Py_XDECREF(future_features);
             PyErr_RangedSyntaxLocationObject(filename,
                                              name->lineno,
                                              name->col_offset + 1,