Fix undefined behavior in EgammaTowerIsolation

[Dr15Jones]

PR description:

Avoid doing iterator arithmetic on an empty container. This code was pointed to by the UBSAN IB.

PR validation:

The code compiles.

[cmsbuild]

The code-checks are being triggered in jenkins.

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-31170/17803

• This PR adds an extra 16KB to repository

[cmsbuild]

A new Pull Request was created by @Dr15Jones (Chris Jones) for master.

It involves the following packages:

RecoEgamma/EgammaIsolationAlgos

@perrotta, @jpata, @cmsbuild, @slava77 can you please review it and eventually sign? Thanks.
@Sam-Harper, @jainshilpi, @lgray, @sobhatta, @afiqaize, @varuns23 this is something you requested to watch as well.
@silviodonato, @dpiparo, @qliphy you are the release manager for this.

cms-bot commands are listed here

[Dr15Jones]

please test

[cmsbuild]

The tests are being triggered in jenkins.

• CMSSW_11_2_X_2020-08-17-2300/slc7_amd64_gcc820: https://cmssdt.cern.ch/jenkins/job/ib-run-pr-tests/8809/console Started: 2020/08/19 00:24

[cmsbuild]

+1
Tested at: 56a5ac9
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-5faf09/8809/summary.html
CMSSW: CMSSW_11_2_X_2020-08-17-2300
SCRAM_ARCH: slc7_amd64_gcc820

The following merge commits were also included on top of IB + this PR after doing git cms-merge-topic:

• Refine RuInfo payload inspector #31128 @mmusich: Refine RuInfo payload inspector
• Remove dead assignments in EventFilter/Utilities/DirManager and Validation/RecoTrack/SiStripTrackingRecHitsValid #31148 @perrotta: Remove dead assignments in EventFilter/Utilities/DirManager and Validation/RecoTrack/SiStripTrackingRecHitsValid
• Introduce SiPhase2OuterTrackerLorentzAngle  #31095 @mmusich: Introduce SiPhase2OuterTrackerLorentzAngle
• [RPC] Changing the RPCDcsInfo* about an issue of the DQM legacy module #31056 @jeongsumin: [RPC] Changing the RPCDcsInfo* about an issue of the DQM legacy module
• Update Alignment/OfflineValidation package #31141 @mmusich: Update Alignment/OfflineValidation package
• Run3-gem51 Add a tool to compare DDD vs DD4HEP for CSC geometry #31144 @bsunanda: Run3-gem51 Add a tool to compare DDD vs DD4HEP for CSC geometry
• Cleanup of the PFTrack class #31151 @hatakeyamak: Cleanup of the PFTrack class
• Add the anti-electron-in-deadECal tauID to NanoAOD #31077 @cms-tau-pog: Add the anti-electron-in-deadECal tauID to NanoAOD

You can see more details here:
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-5faf09/8809/git-log-recent-commits
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-5faf09/8809/git-merge-result

[cmsbuild]

Comparison job queued.

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-5faf09/8809/summary.html

Comparison Summary:

• No significant changes to the logs found
• Reco comparison results: 70 differences found in the comparisons
• DQMHistoTests: Total files compared: 35
• DQMHistoTests: Total histograms compared: 2608220
• DQMHistoTests: Total failures: 5
• DQMHistoTests: Total nulls: 1
• DQMHistoTests: Total successes: 2608192
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: -0.732 KiB( 34 files compared)
• DQMHistoSizes: changed ( 1000.0,... ): -0.042 KiB RPC/DCSInfo
• DQMHistoSizes: changed ( 10024.0,... ): -0.030 KiB RPC/DCSInfo
• DQMHistoSizes: changed ( 10224.0 ): 0.004 KiB MessageLogger/Warnings
• DQMHistoSizes: changed ( 1325.7 ): 0.116 KiB Physics/NanoAODDQM
• Checked 149 log files, 22 edm output root files, 35 DQM output files

[perrotta]

please test
(Test in a newer IB to get rid of the extra commits which end up with changes in the nanoAOD output)

[cmsbuild]

The tests are being triggered in jenkins.

• CMSSW_11_2_X_2020-08-19-1100/slc7_amd64_gcc820: https://cmssdt.cern.ch/jenkins/job/ib-run-pr-tests/8823/console Started: 2020/08/19 15:51

[cmsbuild]

+1
Tested at: 56a5ac9
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-5faf09/8823/summary.html
CMSSW: CMSSW_11_2_X_2020-08-19-1100
SCRAM_ARCH: slc7_amd64_gcc820

[cmsbuild]

Comparison job queued.

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-5faf09/8823/summary.html

Comparison Summary:

• No significant changes to the logs found
• Reco comparison results: 2 differences found in the comparisons
• DQMHistoTests: Total files compared: 35
• DQMHistoTests: Total histograms compared: 2608222
• DQMHistoTests: Total failures: 5
• DQMHistoTests: Total nulls: 1
• DQMHistoTests: Total successes: 2608194
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.004 KiB( 34 files compared)
• DQMHistoSizes: changed ( 10224.0 ): 0.004 KiB MessageLogger/Warnings
• Checked 149 log files, 22 edm output root files, 35 DQM output files

[perrotta]

+1

• Technical fix
• Jenkisn tests pass

[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. @silviodonato, @dpiparo, @qliphy (and backports should be raised in the release meeting by the corresponding L2)

[qliphy]

+1