With the following example program (`ghz.cpp`), ``` __qpu__ void cascadingCNOT(qreg q) { for (std::size_t i = 1; i < q.size(); i++) { CNOT(q[i-1], q[i]); } } __qpu__ void ghz(qreg q) { H(q[0]); cascadingCNOT(q); Measure(q); } int main() { set_verbose(true); auto q = qalloc(32); ghz(q); q.print(); } ``` if you change 32 in the `qalloc()` to the number of qubits on the backend you're targeting (I was using `ibm:ibmq_qasm_simulator`), you can hopefully reproduce the following runtime error: ``` $ ./ghz terminate called after throwing an instance of 'std::logic_error' what(): Not enough physical qubits Aborted (core dumped) ``` The root cause of this appears to be the SyntaxHandler generating the following code that unconditionally runs the PassManager: ``` xacc::internal_compiler::execute_pass_manager(); if (optimize_only) { return; } if (is_callable) { quantum::submit(q.results()); } ```