Failing RemoveImplicitQubitPermutation proptest

[aborgna-q]

A CI job failed when testing the RemoveImplicitQubitPermutation pass (link)

I wasn't able to reproduce the error test locally using the RC_PARAMS.

Output:

conan create --profile=tket recipes/tket-proptests --build=missing --build=tket-proptests
(...)

- n_qubits is correct
OK, passed 100 tests

- preconditions and postconditions of passes are correct
Falsifiable after 83 tests and 5 shrinks

std::tuple<tket::Circuit, std::shared_ptr<tket::BasePass>>:
(Collapse q[0];
Phase(0.5);
Phase(0);
Tdg q[0];
Ry(1) q[0];
NPhasedX(0, 1.25) q[0];
Ry(0) q[0];
U2(0, 0) q[0];
Collapse q[0];
SX q[0];
X q[0];
Rx(1) q[0];
Phase (in half-turns): 0.0
, <???> (00000[18](https://github.com/CQCL/tket/actions/runs/4042509897/jobs/6950304167#step:18:19)6E0F117F0))

no exceptions thrown

Log:

Circuit (1 qubits, 12 gates): Collapse q[0];
Phase(0.5);
Phase(0);
Tdg q[0];
Ry(1) q[0];
NPhasedX(0, 1.[25](https://github.com/CQCL/tket/actions/runs/4042509897/jobs/6950304167#step:18:26)) q[0];
Ry(0) q[0];
U2(0, 0) q[0];
Collapse q[0];
SX q[0];
X q[0];
Rx(1) q[0];
Phase (in half-turns): 0.0

Pass: RemoveImplicitQubitPermutation

New circuit(1 qubits, 12 gates): Collapse q[0];
Phase(0.5);
Phase(0);
Tdg q[0];
Ry(1) q[0];
NPhasedX(0, 1.25) q[0];
Ry(0) q[0];
U2(0, 0) q[0];
Collapse q[0];
SX q[0];
X q[0];
Rx(1) q[0];
Phase (in half-turns): 0.0


Some of your RapidCheck properties had failures. To reproduce these, run with:
RC_PARAMS="reproduce=BYDcyV2Yv5GZpRXav52cgEmbkBCcvNHdj9mbklGdp9mbzBybmBCchN3clNHIhJXZgM2byJXZjRHgTZSn_kSxQPb8bRJdd1XoimurMEkZ+qztN1AskRik5AIgQAwESBAAAUwCBQAACA"

[aborgna-q]

The "no exceptions thrown" message in the output should normally indicate that the pass was successful. There is an open issue in emil-e/rapidcheck#287 with the same problem, but there is no answer as to the cause of it.

I haven't been able to reproduce this specific error, and a proptest run of 100k tests (vs 100 in CI) did not find anything.
I'm closing this bug as unreproducible.