Loading a circuit from a QASM file created from a QuantumVolume circuit fails.

[adekusar-drl]

Information

• Qiskit Terra version: latest sources
• Python version: 3.7
• Operating system: all

What is the current behavior?

There's an exception when an instance of QuantumVolume circuit is saved as a qasm file and then loaded from this file.

Steps to reproduce the problem

Run the script:

from qiskit import QuantumCircuit
from qiskit.circuit.library import QuantumVolume

if __name__ == '__main__':
    qc = QuantumVolume(num_qubits=3)
    qc.qasm(filename="qv.qasm")
    loaded_qc = QuantumCircuit.from_qasm_file("qv.qasm")

There's an exception:

.../envs/dev-terra/python.exe .../qiskit-terra/_sandbox/qv.py
Traceback (most recent call last):
  File ".../qiskit-terra/_sandbox/qv.py", line 12, in <module>
    loaded_qc = QuantumCircuit.from_qasm_file("qv.qasm")
  File ".../qiskit-terra/qiskit/circuit/quantumcircuit.py", line 2056, in from_qasm_file
Error near line 3 Column 15
    return _circuit_from_qasm(qasm)
  File ".../qiskit-terra/qiskit/circuit/quantumcircuit.py", line 3003, in _circuit_from_qasm
    ast = qasm.parse()
  File ".../qiskit-terra/qiskit/qasm/qasm.py", line 53, in parse
    return qasm_p.parse(self._data)
  File ".../qiskit-terra/qiskit/qasm/qasmparser.py", line 1141, in parse
    self.parser.parse(data, lexer=self.lexer, debug=self.parse_deb)
  File ".../envs/dev-terra/lib/site-packages/ply/yacc.py", line 333, in parse
    return self.parseopt_notrack(input, lexer, debug, tracking, tokenfunc)
  File ".../envs/dev-terra/lib/site-packages/ply/yacc.py", line 1120, in parseopt_notrack
    p.callable(pslice)
  File ".../qiskit-terra/qiskit/qasm/qasmparser.py", line 400, in p_id_e
    raise QasmError("Expected an ID, received '" + str(program[1].value) + "'")
qiskit.qasm.exceptions.QasmError: "Expected an ID, received '['"

What is the expected behavior?

No exceptions to be raisen.

[singhmeet11]

Hi, can I work on this issue?

[adekusar-drl]

I don't mind, but I'm not in the development team :)

[singhmeet11]

I took a look at the issue and I am having a hard time and something came up, so if anyone is up to the task go ahead.