includeIronMagFields option segfaults

[Jochem Snuverink]

Including the iron magnetic fields calls the auxNavigator in the AcceleratorComponent::Build method (in itsMagField->GetFieldValue(polePos,Bfield); ) before it is attached to the worldvolume. This results in a segfault:

Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_INVALID_ADDRESS at address: 0x0000000000000010
0x000000010454db82 in G4Navigator::LocateGlobalPointAndSetup ()
(gdb) bt
#0  0x000000010454db82 in G4Navigator::LocateGlobalPointAndSetup ()
#1  0x00000001000f9cb3 in BDSQuadMagField::GetFieldValue (this=0x10a050960, Point=<value temporarily unavailable, due to optimizations>, Bfield=0x7fff5fbfe320) at /Users/jsnuverink/Documents/bdsim/src/BDSQuadMagField.cc:19
#2  0x00000001000f9ef1 in BDSQuadrupole::Build (this=0x10a04fe60) at /Users/jsnuverink/Documents/bdsim/src/BDSQuadrupole.cc:42

This can be reproduced in by e.g. adding the option includeIronMagFields in examples/features/geometry/4_magnets

[Laurie Nevay]

Oh dear. I'll disable outer fields to prevent this for now.

The outer fields have been broken for some time and will be shortly reimplemented. As the implementation (use of auxnavigator) of fields in BDSIM has moved on, this has become very broken. My current understanding was that the outer fields weren't built currently even if requested.

The mechanism for outer fields will be fixed in December with the review of the field construction process.

[Laurie Nevay]

This option will be ignored for now and no external fields will be constructed.

[Jochem Snuverink]

Thanks for the temporary fix. I would like to keep the issue open though until it is properly fixed. Feel free to downgrade priority.

[Laurie Nevay]

I have now implemented outer multipole fields. This is under final testing now and will be merged shortly. It will be in version 1.

The option includeIronFields is retained for backwards compatibility, but this is replaced with "yokeFields".