Fix classical-synthesis label ordering with registerless=False

[1ucian0]

Fixes #9363

from qiskit.circuit.classicalfunction import classical_function
from qiskit.circuit.classicalfunction.types import Int1

@classical_function
def grover_oracle(a: Int1, b: Int1, c: Int1) -> Int1:
    return (a and b and not c)

quantum_circuit = grover_oracle.synth(registerless=False)
print(quantum_circuit.draw())

     a: ──■──
          │  
     b: ──■──
          │  
     c: ──o──
        ┌─┴─┐
return: ┤ X ├
        └───┘

[qiskit-bot]

Thank you for opening a new pull request.

Before your PR can be merged it will first need to pass continuous integration tests and be reviewed. Sometimes the review process can be slow, so please be patient.

While you're waiting, please feel free to review other open PRs. While only a subset of people are authorized to approve pull requests for merging, everyone is encouraged to review open pull requests. Doing reviews helps reduce the burden on the core team and helps make the project's code better for everyone.

One or more of the the following people are requested to review this:

• @Qiskit/terra-core

[coveralls]

Pull Request Test Coverage Report for Build 5868913929

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 23 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.03%) to 87.235%

---

Files with Coverage Reduction	New Missed Lines	%
crates/qasm2/src/lex.rs	5	90.63%
crates/qasm2/src/parse.rs	18	96.2%

Totals
Change from base Build 5868812324:	-0.03%
Covered Lines:	74277
Relevant Lines:	85146

---

💛 - Coveralls

[jakelishman]

Tweedledum isn't a required import, so these lines need to be protected within the function, and it needs decorating with a @unittest.skipUnless(optionals.HAS_TWEEDLEDUM, ...) line.

[1ucian0]

oh! I forgot. Thanks! Fixed in 91069ad

[jakelishman]

This could maybe stand a shade more explanation.

[1ucian0]

True. Adding more in 232e4e5

[jakelishman]

It's either "If there is a gate in the Tweedledum circuit that has no ..." or just delete at the start to make it "If a gate in ..."

[1ucian0]

fixed in aa04278