[ROOT6] Updated root to tip of branch master: LLVM 20

[akritkbehera]

No description provided.

[cmsbuild]

A new Pull Request was created by @akritkbehera for branch IB/CMSSW_16_0_X/rootmaster.

@akritkbehera, @cmsbuild, @iarspider, @smuzaffar can you please review it and eventually sign? Thanks.
@ftenchini, @mandrenguyen, @sextonkennedy you are the release manager for this.
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[cmsbuild]

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[akritkbehera]

Please test

[smuzaffar]

please test with cms-sw/cmssw#49141 for CMSSW_16_0_ROOT6_X

[cmsbuild]

-1

Failed Tests: HeaderConsistency
Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-d1f908/48627/summary.html
COMMIT: d890436
CMSSW: CMSSW_16_0_ROOT6_X_2025-10-12-2300/el8_amd64_gcc13
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week1/cms-sw/cmsdist/10120/48627/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• You potentially added 286 lines to the logs
• Reco comparison results: 47 differences found in the comparisons
• DQMHistoTests: Total files compared: 51
• DQMHistoTests: Total histograms compared: 3940073
• DQMHistoTests: Total failures: 3147
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3936906
• 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

[smuzaffar]

+externals

Lets merge this. cms-sw/cmssw#49141 is already merged (which should fix the ROOT6_X IBs build errors) and cms-sw/cmssw#49146 should fix the header consistency error.

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next IB/CMSSW_16_0_X/rootmaster IBs (but tests are reportedly failing). This pull request will now be reviewed by the release team before it's merged. @mandrenguyen, @sextonkennedy, @ftenchini (and backports should be raised in the release meeting by the corresponding L2)