TypeError: unsupported operand type(s) for |: 'type' and 'type'

[zyl-source]

em5 Simulator System. https://www.gem5.org
gem5 is copyrighted software; use the --copyright option for details.

gem5 version 25.1.0.0
gem5 compiled Mar 9 2026 22:36:14
gem5 started Mar 10 2026 11:23:02
gem5 executing on ubuntu, pid 15478
command line: /home/icer-clear/Gem5/gem5/build/ALL/gem5.opt 01-components.py

TypeError: unsupported operand type(s) for |: 'type' and 'type'

At:
src/python/gem5/simulate/simulator.py(104): Simulator
src/python/gem5/simulate/simulator.py(56):
(40): exec_module
(686): _load_unlocked
(975): _find_and_load_unlocked
(991): _find_and_load
01-components.py(20):
src/python/m5/main.py(687): main

[Flpvoigt]

This traceback points to the Python interpreter embedded in the gem5 binary, not to the simulated workload. type | type in annotations is PEP 604 syntax and is supported at runtime starting with Python 3.10. If gem5 was built against Python 3.9 or older, importing gem5.simulate.simulator can fail exactly this way.

Add this at the very top of 01-components.py, before importing gem5 modules, to confirm the interpreter used by the binary:

import sys
print(sys.version)
print(sys.executable)

If it reports a version below 3.10, install a supported Python 3.10+ development environment and rebuild gem5 so SCons links the binary against that Python. Merely activating a newer virtual environment after gem5.opt has already been compiled is not enough—the interpreter choice is made at build time. Clean the old build output before rebuilding so it is not reused.

If it reports 3.10 or newer, the more likely cause is that the source tree and the compiled binary are out of sync; clean and rebuild the binary from the same checkout.

As a diagnostic only, adding from __future__ import annotations to the affected gem5 source would postpone annotation evaluation, but rebuilding against a supported Python version is the proper fix because other modules may also rely on modern Python features.