Merge pull request #76 from abizer/py314-lineno-fix

Fix crash on Python 3.12+

Author: cknd

.github/workflows/build.yml

@@ -16,7 +16,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
+        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12", "3.13", "3.14"]
     steps:
     - uses: actions/checkout@v3
     - name: Set up Python ${{ matrix.python-version }}

.gitignore

@@ -0,0 +1,10 @@
+__pycache__/
+*.py[cod]
+*$py.class
+
+*.egg-info/
+build/
+dist/
+
+.venv*/
+.pytest_cache/

CHANGELOG.md

@@ -1,3 +1,8 @@
+# 0.2.13 - April 14, 2026
+
+## Fixed
+- Python 3.12+ compatibility: `tb.tb_lineno` and `frame.f_lineno` can return `None` when an instruction has no line mapping (for example at some async suspension points or on synthetic RESUME/CACHE opcodes). `extraction.get_info` now substitutes `frame.f_code.co_firstlineno` in that case instead of crashing with `AssertionError` in `source_inspection.annotate`.
+
 # 0.2.8 - August 25, 2022
 
 ## Fixed

setup.py

@@ -6,7 +6,7 @@
 setuptools.setup(
     python_requires=">=3.4",
     name="stackprinter",
-    version="0.2.12",
+    version="0.2.13",
     author="cknd",
     author_email="ck-github@mailbox.org",
     description="Debug-friendly stack traces, with variable values and semantic highlighting",

stackprinter/extraction.py

@@ -83,6 +83,14 @@ def get_info(tb_or_frame, lineno=None, suppressed_vars=[]):
     else:
         raise ValueError('Cant inspect this: ' + repr(tb_or_frame))
 
+    # Since CPython 3.12, both `tb.tb_lineno` and `frame.f_lineno` can return
+    # None when the current instruction has no line mapping (for example at
+    # certain async suspension points, or on synthetic RESUME/CACHE opcodes).
+    # Fall back to the function's first line so we can still render a frame
+    # rather than crashing downstream formatters with a None lineno.
+    if lineno is None:
+        lineno = frame.f_code.co_firstlineno
+
     filename = inspect.getsourcefile(frame) or inspect.getfile(frame)
     function = frame.f_code.co_name
 

tests/test_formatting.py

@@ -55,3 +55,36 @@ def test_none_tuple_formatting():
 def test_none_value_formatting():
     output = stackprinter.format((TypeError, None, None))
     assert output == "TypeError: None"
+
+
+def test_tb_with_none_lineno():
+    # Regression Python 3.12+ compat.
+    # Since CPython 3.12, `tb.tb_lineno` (and `frame.f_lineno`) return None when
+    # the instruction at tb_lasti has no line mapping. Stackprinter used to pass
+    # that None straight into source_inspection.annotate() and blow up on
+    # `assert isinstance(lineno, int)`. It should now fall back gracefully.
+    import sys
+    import types
+
+    import pytest
+
+    captured = []
+
+    def target():
+        captured.append(sys._getframe())
+
+    target()
+    frame = captured[0]
+
+    # An out-of-range tb_lasti makes CPython's tb_lineno getter return None via
+    # its Py_RETURN_NONE fallback path.
+    tb = types.TracebackType(None, frame, 1 << 20, -1)
+    if tb.tb_lineno is not None:
+        pytest.skip(
+            "tb.tb_lineno didn't return None on this interpreter "
+            f"({sys.version_info}); regression only applies when it does."
+        )
+
+    output = stackprinter.format((ValueError, ValueError("boom"), tb))
+    assert "target" in output
+    assert "ValueError: boom" in output