Assertion error on valid-standalone measurement

[ryanhill1]

In OpenQASM grammar, it seems that it might not be required that measurement statements make reference to a classical (target) qubit.

The openqasm3.ast.QuantumMeasurementStatement is documented as:

Stand-alone statement of a quantum measurement, potentially assigning the result to a classical variable.

and specifies field target of type Optional[Union[IndexedIdentifier, Identifier]].

This makes me think that specifying a target (classical) bit might not be semantically necessary.

If this is true, the following should be valid:

OPENQASM 3.0;
include "stdgates.inc";

qubit[3] q;
bit[3] b;

h q[0];
cx q[0], q[1];
measure q;

However, in pyqasm.unroll(), it raises an AssertionError:

pyqasm/src/pyqasm/visitor.py

Lines 441 to 443 in 0fd2956

	source = statement.measure.qubit
	target = statement.target
	assert source and target

[arulandu]

Yeah, this example is valid. Working on it