Incorrect compilation of within/apply block when code contains @EntryPoint()

[rmshaffer]

Describe the bug
When the code in a notebook contains @EntryPoint(), the adjoint of any within block is not applied.

(Thanks to @cgranade for finding and reporting this issue.)

To Reproduce
Steps to reproduce the behavior:

1. Execute the following code in a Q# notebook cell:

   operation HXH() : Unit {
       using (q = Qubit()) {
           within { H(q); }
           apply { X(q); }
       }
   }
   
   @EntryPoint()
   operation DoNothing() : Unit {}
   

2. Run %simulate HXH.

3. This fails with the error: Released qubits are not in zero state. Inspection of the generated C# code reveals that the final H operation is not being applied.

Expected behavior
Operation should run successfully, since if compiled correctly, the qubits would be in the zero state when released.

Note that if the @EntryPoint() line is removed, everything works fine.

Screenshots
If applicable, add screenshots to help explain your problem.

System information

• OS: Windows
• Browser: Edge
• Version: Latest master (as of 2020-08-13)

[guenp]

It looks like this error also occurs when importing an operation from a Q# project when there is a file present with an EntryPoint() (thanks @cgranade for help in figuring this out):

> from Microsoft.Quantum.Samples.Chemistry.VariationalQuantumEigensolver import EstimateEnergy
> EstimateEnergy.simulate(...)

Unhandled exception. System.NotImplementedException: The method or operation is not implemented.
 ---> Microsoft.Quantum.Samples.Chemistry.VQE.StatePreparation.PrepareSingleConfigurationalStateSingleSiteOccupation on /workspaces/Quantum/samples/chemistry/VariationalQuantumEigensolver/StatePreparation.qs:line 0
   at Microsoft.Quantum.Canon.ApplyControlledOnBitString on /workspaces/Quantum/samples/chemistry/VariationalQuantumEigensolver/D:\a\1\s\submodules\QuantumLibraries\Standard\src\Canon\Utils\ControlledOnBitString.qs:line 0
   at Microsoft.Quantum.Canon.ApplyControlledOnInt on /workspaces/Quantum/samples/chemistry/VariationalQuantumEigensolver/D:\a\1\s\submodules\QuantumLibraries\Standard\src\Canon\Utils\ControlledOnBitString.qs:line 0
   at Microsoft.Quantum.Canon.MultiplexOperationsBruteForceFromGenerator on /workspaces/Quantum/samples/chemistry/VariationalQuantumEigensolver/D:\a\1\s\submodules\QuantumLibraries\Standard\src\Canon\Multiplexer.qs:line 0
   at Microsoft.Quantum.Samples.Chemistry.VQE.StatePreparation.PrepareSparseMultiConfigurationalState on /workspaces/Quantum/samples/chemistry/VariationalQuantumEigensolver/StatePreparation.qs:line 0
   at Microsoft.Quantum.Samples.Chemistry.VQE.StatePreparation.PrepareTrialState on /workspaces/Quantum/samples/chemistry/VariationalQuantumEigensolver/StatePreparation.qs:line 0
   at Microsoft.Quantum.Samples.Chemistry.VQE.EstimateEnergy.TermExpectation on /workspaces/Quantum/samples/chemistry/VariationalQuantumEigensolver/EstimateEnergy.qs:line 0
   at Microsoft.Quantum.Samples.Chemistry.VQE.EstimateEnergy.SumTermExpectation on /workspaces/Quantum/samples/chemistry/VariationalQuantumEigensolver/EstimateEnergy.qs:line 0
   at Microsoft.Quantum.Samples.Chemistry.VariationalQuantumEigensolver.EstimateEnergy on /workspaces/Quantum/samples/chemistry/VariationalQuantumEigensolver/VariationalQuantumEigensolver.qs:line 0

The method or operation is not implemented.

[rmshaffer]

Thanks @guenp, good find. I will follow up on microsoft/qsharp-compiler#571 to see whether this is something that can be addressed soon, since this seems like a much more common scenario than having an @EntryPoint() in a notebook.