[FWCore] Fix segmentation fault in testRefInROOT::testGoodChain when using TChain

[akritkbehera]

PR description:

This PR fixes a segmentation fault in testRefInROOT::testGoodChain caused by calling SetBranchAddress() before the TChain had loaded its first tree.
TChain::SetBranchAddress() requires fTree to be initialized (fTreeNumber >= 0), which wasn’t the case — resulting in null TBranch* pointers and a crash at runtime.

[cmsbuild]

cms-bot internal usage

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-49103/46338

[akritkbehera]

Please test

[cmsbuild]

A new Pull Request was created by @akritkbehera for master.

It involves the following packages:

• FWCore/FWLite (core)

@Dr15Jones, @makortel, @smuzaffar can you please review it and eventually sign? Thanks.
@makortel, @wddgit this is something you requested to watch as well.
@ftenchini, @mandrenguyen, @sextonkennedy you are the release manager for this.

cms-bot commands are listed here

[cmsbuild]

-1

Failed Tests: ClangBuild
Size: This PR adds an extra 16KB to repository
Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-41ccf2/48555/summary.html
COMMIT: 9109c63
CMSSW: CMSSW_16_0_X_2025-10-08-1100/el8_amd64_gcc13
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week0/cms-sw/cmssw/49103/48555/install.sh to create a dev area with all the needed externals and cmssw changes.

Clang Build

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

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

See details on the summary page.

[cmsbuild]

REMINDER @ftenchini, @sextonkennedy, @mandrenguyen: This PR was tested with cms-sw/cmsdist#10111, please check if they should be merged together

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-49103/46354

[cmsbuild]

Pull request #49103 was updated. @Dr15Jones, @cmsbuild, @makortel, @smuzaffar can you please check and sign again.

[akritkbehera]

Please test

[cmsbuild]

+1

Size: This PR adds an extra 24KB to repository
Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-41ccf2/48558/summary.html
COMMIT: b9e737e
CMSSW: CMSSW_16_0_X_2025-10-08-1100/el8_amd64_gcc13
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week0/cms-sw/cmssw/49103/48558/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• You potentially added 1 lines to the logs
• Reco comparison results: 8 differences found in the comparisons
• DQMHistoTests: Total files compared: 51
• DQMHistoTests: Total histograms compared: 3940073
• DQMHistoTests: Total failures: 419
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3939634
• DQMHistoTests: Total skipped: 20
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 50 files compared)
• Checked 218 log files, 188 edm output root files, 51 DQM output files
• TriggerResults: no differences found

[makortel]

Comparison differences are related to #47071 and #49073

[makortel]

+core

[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. @mandrenguyen, @ftenchini, @sextonkennedy (and backports should be raised in the release meeting by the corresponding L2)

[ftenchini]

+1