gh-134235: Import Autocomplete for Builtin Modules

Lib/_pyrepl/_module_completer.py

@@ -81,8 +81,9 @@ def find_modules(self, path: str, prefix: str) -> list[str]:
     def _find_modules(self, path: str, prefix: str) -> list[str]:
         if not path:
             # Top-level import (e.g. `import foo<tab>`` or `from foo<tab>`)`
-            return [name for _, name, _ in self.global_cache
-                    if name.startswith(prefix)]
+            builtin_modules = [name for name in sys.builtin_module_names if name.startswith(prefix)]
+            third_party_modules = [name for _, name, _ in self.global_cache if name.startswith(prefix)]
+            return sorted(builtin_modules + third_party_modules)
 
         if path.startswith('.'):
             # Convert relative path to absolute path

Lib/test/test_pyrepl/test_pyrepl.py

@@ -959,6 +959,26 @@ def test_import_completions(self):
                 output = reader.readline()
                 self.assertEqual(output, expected)
 
+    def test_builtin_completion_top_level(self):
+        import importlib
+        # Make iter_modules() search only the standard library.
+        # This makes the test more reliable in case there are
+        # other user packages/scripts on PYTHONPATH which can
+        # intefere with the completions.
+        lib_path = os.path.dirname(importlib.__path__[0])
+        sys.path = [lib_path]
+
+        cases = (
+            ("import bui\t\n", "import builtins"),
+            ("from bui\t\n", "from builtins"),
+        )
+        for code, expected in cases:
+            with self.subTest(code=code):
+                events = code_to_events(code)
+                reader = self.prepare_reader(events, namespace={})
+                output = reader.readline()
+                self.assertEqual(output, expected)
+
     def test_relative_import_completions(self):
         cases = (
             ("from .readl\t\n", "from .readline"),

Misc/NEWS.d/next/Library/2025-05-19-15-05-24.gh-issue-134235.pz9PwV.rst

@@ -0,0 +1,2 @@
+Updated tab completion on REPL to include builtin modules. Contributed by
+Tom Wang, Hunter Young