Fix SystemError during REPL input compilation corrupting display

Author: johnslavik

Lib/_pyrepl/simple_interact.py

@@ -83,7 +83,7 @@ def _more_lines(console: code.InteractiveConsole, unicodetext: str) -> bool:
     src = _strip_final_indent(unicodetext)
     try:
         code = console.compile(src, "<stdin>", "single")
-    except (OverflowError, SyntaxError, ValueError):
+    except (OverflowError, SyntaxError, ValueError, SystemError):
         lines = src.splitlines(keepends=True)
         if len(lines) == 1:
             return False

Lib/code.py

@@ -44,8 +44,8 @@ def runsource(self, source, filename="<input>", symbol="single"):
         One of several things can happen:
 
         1) The input is incorrect; compile_command() raised an
-        exception (SyntaxError or OverflowError).  A syntax traceback
-        will be printed by calling the showsyntaxerror() method.
+        exception.  A syntax traceback will be printed by calling
+        the showsyntaxerror() method.
 
         2) The input is incomplete, and more input is required;
         compile_command() returned None.  Nothing happens.
@@ -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_pyrepl/support.py

@@ -44,7 +44,7 @@ def more_lines(text: str, namespace: dict | None = None):
     console = InteractiveConsole(namespace, filename="<stdin>")
     try:
         code = console.compile(src, "<stdin>", "single")
-    except (OverflowError, SyntaxError, ValueError):
+    except (OverflowError, SyntaxError, ValueError, SystemError):
         return False
     else:
         return code is None

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 @@
+Fix ``PyREPL`` and :mode:`code` REPL mishandling a :exc:`SystemError` from the compiler. Patch by Bartosz Sławecki.