Fix SystemError during REPL input compilation corrupting display

Author: johnslavik

Lib/_pyrepl/simple_interact.py

@@ -93,6 +93,8 @@ def _more_lines(console: code.InteractiveConsole, unicodetext: str) -> bool:
         not_empty = last_line.strip() != ""
         incomplete = not last_line.endswith("\n")
         return (was_indented or not_empty) and incomplete
+    except SystemError:
+        return False
     else:
         return code is None
 

Lib/code.py

@@ -62,7 +62,7 @@ def runsource(self, source, filename="<input>", symbol="single"):
         """
         try:
             code = self.compile(source, filename, symbol)
-        except (OverflowError, SyntaxError, ValueError):
+        except (OverflowError, SyntaxError, ValueError, SystemError):
             # Case 1
             self.showsyntaxerror(filename, source=source)
             return False

Lib/codeop.py

@@ -71,6 +71,8 @@ def _maybe_compile(compiler, source, filename, symbol, flags):
             except SyntaxError:
                 pass
                 # fallthrough
+            except SystemError as exc:
+                raise exc from None
 
     return compiler(source, filename, symbol, incomplete_input=False)
 
@@ -147,8 +149,8 @@ def __call__(self, source, filename="<input>", symbol="single"):
 
         - Return a code object if the command is complete and valid
         - Return None if the command is incomplete
-        - Raise SyntaxError, ValueError or OverflowError if the command is a
-          syntax error (OverflowError and ValueError can be produced by
-          malformed literals).
+        - Raise SyntaxError, ValueError, OverflowError or SystemError.
+          OverflowError and ValueError can be produced by malformed
+          literals, SystemError if source cannot be compiled.
         """
         return _maybe_compile(self.compiler, source, filename, symbol, flags=self.compiler.flags)

Lib/test/test_codeop.py

@@ -6,8 +6,9 @@
 import warnings
 from test.support import warnings_helper
 from textwrap import dedent
+from unittest.mock import Mock
 
-from codeop import compile_command, PyCF_DONT_IMPLY_DEDENT
+from codeop import compile_command, _maybe_compile, PyCF_DONT_IMPLY_DEDENT
 
 class CodeopTests(unittest.TestCase):
 
@@ -325,6 +326,5 @@ def foo(x,x):
             """), "duplicate parameter 'x' in function definition")
 
 
-
 if __name__ == "__main__":
     unittest.main()

Lib/test/test_pyrepl/test_interact.py

@@ -275,6 +275,13 @@ def test_incomplete_statement(self):
         console = InteractiveColoredConsole(namespace, filename="<stdin>")
         self.assertTrue(_more_lines(console, code))
 
+    def test_system_error_during_compilation(self):
+        namespace = {}
+        console = InteractiveColoredConsole(namespace, filename="<stdin>")
+        with patch.object(console, "compile", side_effect=SystemError("compiler bug")):
+            result = _more_lines(console, "some code")
+        self.assertFalse(result)
+
 
 class TestWarnings(unittest.TestCase):
     def test_pep_765_warning(self):

Misc/NEWS.d/next/Library/2026-06-01-21-31-06.gh-issue-150732.WqHBvP.rst

@@ -0,0 +1,2 @@
+Fix :exc:`SystemError` raised during input compilation in the REPL corrupting
+the display and leaking :exc:`!_IncompleteInputError` in the exception chain.