From aaa535d2c287c56822e6d76ec541f578d685f6e6 Mon Sep 17 00:00:00 2001
From: AC <ac@fabtek.cn>
Date: Tue, 13 Oct 2026 10:43:40 +0800
Subject: [PATCH] Preserve SyntaxError attributes when formatting interpreter
 errors

---
 bpython/repl.py                  | 11 +++----
 bpython/test/test_interpreter.py | 53 ++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+), 7 deletions(-)

diff --git a/bpython/repl.py b/bpython/repl.py
index 93ce5cbc..85a6e5b1 100644
--- a/bpython/repl.py
+++ b/bpython/repl.py
@@ -161,14 +161,11 @@ def showsyntaxerror(self, filename: str | None = None, **kwargs) -> None:
         exc_type, value, sys.last_traceback = sys.exc_info()
         sys.last_type = exc_type
         sys.last_value = value
-        if filename and exc_type is SyntaxError and value is not None:
-            msg = value.args[0]
-            args = list(value.args[1])
-            # strip linechache line number
+        if filename and isinstance(value, SyntaxError):
+            # Hide the linecache identifier without rebuilding the exception:
+            # compiler errors can have location attributes but only one arg.
             if self.bpython_input_re.match(filename):
-                args[0] = "<input>"
-            value = SyntaxError(msg, tuple(args))
-            sys.last_value = value
+                value.filename = "<input>"
         exc_formatted = traceback.format_exception_only(exc_type, value)
         self.writetb(exc_formatted)
 
diff --git a/bpython/test/test_interpreter.py b/bpython/test/test_interpreter.py
index 3d40d198..668f3aa0 100644
--- a/bpython/test/test_interpreter.py
+++ b/bpython/test/test_interpreter.py
@@ -1,4 +1,6 @@
 import unittest
+import sys
+from unittest.mock import Mock
 
 from curtsies.fmtfuncs import bold, green, magenta, cyan, red, plain
 
@@ -34,6 +36,57 @@ def test_syntaxerror(self):
         self.assertMultiLineEqual(str(plain("").join(a)), str(expected))
         self.assertEqual(plain("").join(a), expected)
 
+    def test_semantic_syntaxerrors_leave_interpreter_usable(self):
+        for source in ("nonlocal a", "return", "break", "continue"):
+            with self.subTest(source=source):
+                i = Interpreter()
+                callback = Mock()
+                i.syntaxerror_callback = callback
+                self.assertFalse(i.runsource(source))
+                callback.assert_called_once_with()
+                output = str(plain("").join(i.a))
+                self.assertIn("SyntaxError", output)
+                self.assertIn('"<input>"', output)
+                self.assertNotIn("<bpython-input-", output)
+                self.assertIsInstance(sys.last_value, SyntaxError)
+                self.assertEqual(sys.last_value.filename, "<input>")
+                self.assertFalse(i.runsource("answer = 6 * 7"))
+                self.assertEqual(i.locals["answer"], 42)
+
+    def test_syntaxerror_keeps_original_exception_and_details(self):
+        i = Interpreter()
+        error = SyntaxError("message")
+        error.filename = "<bpython-input-123>"
+        error.lineno = 3
+        error.offset = 2
+        error.end_lineno = 3
+        error.end_offset = 5
+        error.text = "bad source"
+        error.add_note("additional information")
+        try:
+            raise error
+        except SyntaxError:
+            i.showsyntaxerror(error.filename)
+        self.assertIs(sys.last_value, error)
+        self.assertEqual(error.filename, "<input>")
+        self.assertEqual((error.lineno, error.offset), (3, 2))
+        self.assertEqual((error.end_lineno, error.end_offset), (3, 5))
+        self.assertIn("additional information", str(plain("").join(i.a)))
+
+    def test_explicit_syntaxerror_filename(self):
+        i = Interpreter()
+        i.runsource("1.1.1.1", filename="example.py")
+        self.assertIn('"example.py"', str(plain("").join(i.a)))
+        self.assertEqual(sys.last_value.filename, "example.py")
+
+    def test_indentationerror_filename(self):
+        i = Interpreter()
+        i.runsource("  answer = 42")
+        output = str(plain("").join(i.a))
+        self.assertIn("IndentationError", output)
+        self.assertIn('"<input>"', output)
+        self.assertIsInstance(sys.last_value, IndentationError)
+
     def test_traceback(self):
         i = Interpreter()