Change from int to StarMagField::EBField type

[genevb]

Resolves a run-time error seen in tests of compiling software for ROOT 6.16.00. I also tested this fix in ROOT 5.34.38 to be sure it doesn't break it.

-Gene

---

root4star -b -q -l 'bfc.C(-1)'

...

QA :INFO - ProcessLine if (!StarMagField::Instance()) new StarMagField( 2, 1.000000, kTRUE);
input_line_668:2:37: error: no matching constructor for initialization of 'StarMagField'
if (!StarMagField::Instance()) new StarMagField( 2, 1.000000, kTRUE);
^ ~~~~~~~~~~~~~~~~~~
/afs/rhic.bnl.gov/star/packages/SL23x/.sl73_x8664_gcc485/include/StarMagField.h:155:3: note: candidate constructor not viable: no known conversion from 'int' to 'StarMagField::EBField' for 1st argument
StarMagField ( EBField map = kMapped, Float_t Factor = 1,
^
/afs/rhic.bnl.gov/star/packages/SL23x/.sl73_x8664_gcc485/include/StarMagField.h:91:7: note: candidate constructor (the implicit copy constructor) not viable: requires 1 argument, but 3 were provided
class StarMagField : public TVirtualMagField
^
BFC:ERROR - StBFChain::ProcessLine command:if (!StarMagField::Instance()) new StarMagField( 2, 1.000000, kTRUE); has failed. Quit job.

[plexoos]

Hm, it is strange that we don't see this runtime error for StarMagField in our CI jobs with ROOT 6.16. We don't run specifically 'bfc.C(-1)' but I would think the initialization is the same.

The change itself is good. We should favor named constants

[genevb]

Hm, it is strange that we don't see this runtime error for StarMagField in our CI jobs with ROOT 6.16. We don't run specifically 'bfc.C(-1)' but I would think the initialization is the same.

Running bfc.C(-1) results in turning on the chain option Test.default.ITTF (see below) which leads eventually to turning on the option FieldOn, which causes this line of code to be called in StBFChain.cxx. Normal chains do not have these options turned on. It isn't the most important test, but it's simple to execute and does test a lot of details.

From bfc.C:

TString defChain("y2010,gstar,Test.default.ITTF,NosvtIT,NossdIT,-sfs,-ssdFast,sdt20100107.110000");