Fix arguments in combineCreateNLL call within FitDiagnostics

[anigamova]

Addresses https://cms-talk.web.cern.ch/t/warning-when-running-fitdiagnostics/140247

Summary by CodeRabbit

• Bug Fixes
  • Improved diagnostics and uncertainty calculations to yield more consistent nuisance handling and restore expected backend behavior, reducing spurious warnings and improving stability of fit diagnostics.

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[coderabbitai]

Walkthrough

A single parameter was added to the nuisance NLL construction in FitDiagnostics.cc: the combineCreateNLL call now includes offset = true placed before the warnAboutDifferentBackend flag, changing the created NLL object while preserving the surrounding backend restore logic.

Changes

Cohort / File(s)	Summary
NLL Offset Parameter Addition src/FitDiagnostics.cc	Modified the combineCreateNLL call to include an offset = true parameter for nuisance NLL construction, shifting the parameter order while maintaining backend handling logic.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

• Single-spot parameter addition; check that offset = true is the intended semantics.
• Verify parameter ordering and that backend restore behavior remains unchanged.

Poem

🐰 A tiny tweak, a joyful hop,
Offset set true — the silence stops,
NLL shaped with one small tune,
Restored backends hum in tune,
Rabbity cheers under the moon 🌙

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Fix arguments in combineCreateNLL call within FitDiagnostics' directly and specifically describes the main change: fixing function arguments in a specific code location.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch fitdiag_warnbug

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📜 Recent review details

Configuration used: defaults

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 11b7776 and 6ef3f53.

📒 Files selected for processing (1)

• src/FitDiagnostics.cc (1 hunks)

🚧 Files skipped from review as they are similar to previous changes (1)

• src/FitDiagnostics.cc

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (10)

• GitHub Check: LCG_108 - ROOT 6.36.02
• GitHub Check: CMSSW_14_0_0_pre1 - ROOT 6.26.11
• GitHub Check: CMSSW_11_3_4 - ROOT 6.22.09
• GitHub Check: dev3/latest - ROOT LCG master
• GitHub Check: CMSSW_14_1_0_pre4 - ROOT 6.30.07
• GitHub Check: LCG_102 - ROOT 6.26.04
• GitHub Check: LCG_106 - ROOT 6.32.02
• GitHub Check: Compile (py3.10, root6.26.4)
• GitHub Check: Compile (py3.10, root6.32.2)
• GitHub Check: Compile (py3.12, root6.34.4)

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[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 20.69%. Comparing base (f77cd93) to head (6ef3f53).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/FitDiagnostics.cc	0.00%	1 Missing ⚠️

❌ Your patch status has failed because the patch coverage (0.00%) is below the target coverage (98.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1195   +/-   ##
=======================================
  Coverage   20.69%   20.69%           
=======================================
  Files         195      195           
  Lines       26156    26156           
  Branches     3923     3923           
=======================================
  Hits         5413     5413           
  Misses      20743    20743           

Files with missing lines	Coverage Δ
src/FitDiagnostics.cc	3.48% <0.00%> (ø)

Files with missing lines	Coverage Δ
src/FitDiagnostics.cc	3.48% <0.00%> (ø)

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