Left-addition of cirq.GateOperation with cirq.Circuit raises TypeError #7706
Description
Describe the issue
Creating a standalone cirq.GateOperation (so not wrapped in a list or cirq.FrozenCircuit, for example) and adding it first to some other cirq.Circuit object now (in 1.7.0.dev20251014004317) raises a TypeError when it did not do so in previous cirq versions (cirq-core<=1.6.1).
Explain how to reproduce the bug or problem
Previously (testing in cirq-core==1.6.1), a snippet like
import cirq
h_gate = cirq.H(cirq.q(0))
circuit = h_gate + cirq.Circuit(cirq.CNOT(cirq.q(0), cirq.q(1)))would work the same as if:
cirq.Circuit(cirq.H(cirq.q(0)), cirq.CNOT(cirq.q(0), cirq.q(1)))However, cirq-core==1.7.0.dev20251014004317 throws
h_gate = cirq.H(cirq.q(0))
circuit = h_gate + cirq.Circuit(cirq.CNOT(cirq.q(0), cirq.q(1)))
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
Cell In[4], line 1
----> 1 circuit = h_gate + cirq.Circuit(cirq.CNOT(cirq.q(0), cirq.q(1)))
File ~/.venvs/ex_env/lib/python3.13/site-packages/cirq/ops/gate_operation.py:335, in GateOperation.__add__(self, other)
334 def __add__(self, other):
--> 335 return 1 * self + otherAn error is not raised, though, with these cases:
circuit = cirq.Circuit(cirq.X(cirq.q(0))) + h_gate + cirq.Circuit(cirq.CNOT(cirq.q(0), cirq.q(1)))
# or
circuit = cirq.Circuit(cirq.CNOT(cirq.q(0), cirq.q(1))) + h_gate
# or
h_gate = cirq.H.on_each(cirq.q(0)) # A `list` essentially
circuit = h_gate + cirq.Circuit(cirq.CNOT(cirq.q(0), cirq.q(1)))Tell us the version of Cirq where this happens
This is happening in at least cirq-core==1.7.0.dev20250925223930 onwards, and looks to be stemming from 6816824