Fix problem with fromTrackerSeeds parameter in ElectronSeedProducer and improve LayerMeasurements class

[guitargeek]

PR description:

This PR intends to fix #27541.

If the fromTrackerSeeds parameter in the ElectronSeedProducer would be set to false, a segfault would occur, as detected in the UBSAN IB. This never happened in practice because fromTrackerSeeds = False is actually not supported and triggers an exception [1].

We understand now that fromTrackerSeeds is never supposed to be False and therefore we can just remove all branches in the code for this case, fixing both the issue and simplifying the code.

When I tried to fix the issue, I initially didn't know how it could be fixed and did some changes with the goal of making the problem more obvious to me. This involved changing the LayerMeasurements class such that there are no pointers anymore which can be nullptr and therefore cause trouble when dereferenced. In retrospect, this has nothing to do with the actual issue, but I include this change anyway in the PR as I think it's an improvement.

This caused the interface of LayerMeasurements to change a little bit, and while adapting the code I found an unused function in some muon plugins which could be removed. It was apparently replaced by a more efficient function.

[1] https://github.com/cms-sw/cmssw/blob/master/RecoEgamma/EgammaElectronAlgos/src/ElectronSeedGenerator.cc#L275

PR validation:

CMSSW compiles and local matrix tests pass.

if this PR is a backport please specify the original PR:

No backports intended.

[cmsbuild]

The code-checks are being triggered in jenkins.

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-28039/11971

• This PR adds an extra 48KB to repository

[cmsbuild]

A new Pull Request was created by @guitargeek (Jonas Rembser) for master.

It involves the following packages:

FastSimulation/Muons
RecoEgamma/EgammaElectronAlgos
RecoMuon/TrackerSeedGenerator
RecoTracker/TkTrackingRegions
TrackingTools/MeasurementDet

@perrotta, @ssekmen, @lveldere, @sbein, @civanch, @mdhildreth, @cmsbuild, @slava77 can you please review it and eventually sign? Thanks.
@felicepantaleo, @jainshilpi, @abbiendi, @echapon, @varuns23, @battibass, @makortel, @jhgoh, @lgray, @HuguesBrun, @trocino, @rociovilar, @Sam-Harper, @GiacomoSguazzoni, @rovere, @VinInn, @bellan, @mschrode, @ebrondol, @dgulhan, @calderona, @bachtis, @gpetruc, @matt-komm, @folguera this is something you requested to watch as well.
@davidlange6, @slava77, @fabiocos you are the release manager for this.

cms-bot commands are listed here

[slava77]

@cmsbuild please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-run-pr-tests/2599/console Started: 2019/09/20 20:03

[cmsbuild]

-1

Tested at: a441485

You can see the results of the tests here:
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-a56221/2599/summary.html

I found follow errors while testing this PR

Failed tests: ClangBuild

• Clang:

I found compilation warning while trying to compile with clang. Command used:

USER_CUDA_FLAGS='--expt-relaxed-constexpr' USER_CXXFLAGS='-Wno-register -fsyntax-only' scram build -k -j 32 COMPILER='llvm compile'

See details on the summary page.

[cmsbuild]

Comparison not run due to Build errors/Fireworks only changes/No short matrix requested (RelVals and Igprof tests were also skipped)

[cmsbuild]

+1
Tested at: 20455a4
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-a56221/2728/summary.html

[cmsbuild]

Comparison job queued.

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-a56221/2728/summary.html

Comparison Summary:

• No significant changes to the logs found
• Reco comparison results: 0 differences found in the comparisons
• DQMHistoTests: Total files compared: 34
• DQMHistoTests: Total histograms compared: 2958092
• DQMHistoTests: Total failures: 1
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 2957750
• DQMHistoTests: Total skipped: 341
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 33 files compared)
• Checked 145 log files, 15 edm output root files, 34 DQM output files

[slava77]

+1

for #28039 20455a4

• code changes are in line with the PR description and the follow up review; the changes are technical and should not produce any differences in outputs
• jenkins tests pass and comparisons with the baseline show no differences

[fabiocos]

@ssekmen @sbein could you please have a look? The fastsim part of this PR looks limited

[sbein]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next master IBs (tests are also fine). This pull request will now be reviewed by the release team before it's merged. @davidlange6, @slava77, @smuzaffar, @fabiocos (and backports should be raised in the release meeting by the corresponding L2)

[fabiocos]

+1