clang-tidy: resolve readability-const-return-type in virtual

[greenc-FNAL]

• Code quality: Resolved readability-const-return-type for the virtual mode() accessor.
• API consistency: Updated IStorage_File, Storage_File, and its implementation to return char instead of top-level const char.
• Behavior: No functional behavior changed.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: 4b6db7e1-1dcb-4eb3-964c-4212579d7863

📥 Commits

Reviewing files that changed from the base of the PR and between 0be155e and e41f458.

📒 Files selected for processing (3)

• form/storage/istorage.hpp
• form/storage/storage_file.cpp
• form/storage/storage_file.hpp

📜 Recent review details

⏰ Context from checks skipped due to timeout. (3)

• GitHub Check: build (gcc, none)
• GitHub Check: coverage
• GitHub Check: clang-tidy-check

🧰 Additional context used

📓 Path-based instructions (3)

**/*.{cpp,cc,cxx,h,hpp}

📄 CodeRabbit inference engine (.github/copilot-instructions.md)

**/*.{cpp,cc,cxx,h,hpp}: Use clang-format tool for all C++ code formatting (VS Code auto-formats on save); configuration defined in .clang-format with 100-character line limit and 2-space indentation
Follow clang-tidy recommendations defined in .clang-tidy

Files:

• form/storage/istorage.hpp
• form/storage/storage_file.hpp
• form/storage/storage_file.cpp

**/*.{hpp,cpp}

📄 CodeRabbit inference engine (AGENTS.md)

**/*.{hpp,cpp}: Use .hpp for header files, .cpp for implementation, and *_test.cpp for test files in C++
Enforce 100-character line limit and 2-space indentation in C++ code via .clang-format
Use QualifierAlignment: Right (east-const) style: int const x not const int x in C++
Use PointerAlignment: Left in C++ (pointer * attached to type, not variable name)
All C++ identifiers must use lower_case naming: namespaces, classes, structs, enums, functions, variables, parameters, members, and constants
Exception to C++ naming: template parameters use CamelCase
Exception to C++ naming: macros use UPPER_CASE
Private, protected, and constant members in C++ must have a trailing underscore (_), no trailing underscore on anything else
Use enum class preferred over plain enum in C++
Use std::shared_ptr for shared ownership, std::unique_ptr for exclusive ownership, raw pointers for non-owning references only in C++
Use functors with agent-noun pattern: ModelEvaluator evaluate_model(...) in C++
Apply .clang-tidy checks for bugprone, cert, clang-analyzer, concurrency, cppcoreguidelines, misc, modernize, performance, portability, and readability as defined in the .clang-tidy configuration file
Use phlex:: namespace for core code, phlex::experimental:: for experimental features in C++

Files:

• form/storage/istorage.hpp
• form/storage/storage_file.hpp
• form/storage/storage_file.cpp

**/*.hpp

📄 CodeRabbit inference engine (AGENTS.md)

Avoid boolean parameters in C++ interfaces; prefer enumerations instead

Files:

• form/storage/istorage.hpp
• form/storage/storage_file.hpp

🔇 Additional comments (3)

form/storage/istorage.hpp (1)

56-56: LGTM!

form/storage/storage_file.hpp (1)

17-17: LGTM!

form/storage/storage_file.cpp (1)

11-11: LGTM!

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📝 Walkthrough

Walkthrough

The storage file mode() accessor now returns char instead of char const consistently across its interface, override declaration, and implementation.

Changes

Storage mode return type

Layer / File(s)	Summary
Align mode signatures form/storage/istorage.hpp, form/storage/storage_file.hpp, form/storage/storage_file.cpp	The mode() interface, override, and implementation now return char while preserving the returned member value.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Suggested reviewers: knoepfel

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: fixing a clang-tidy const-return-type warning on a virtual accessor.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch maintenance/fix-virtual-const-return-type

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

@@            Coverage Diff             @@
##             main     #770      +/-   ##
==========================================
- Coverage   83.82%   83.81%   -0.02%     
==========================================
  Files         172      172              
  Lines        7210     7210              
  Branches      848      848              
==========================================
- Hits         6044     6043       -1     
- Misses        884      885       +1     
  Partials      282      282              

Flag	Coverage Δ
scripts	80.09% <ø> (ø)
unittests	85.68% <100.00%> (-0.03%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
form/storage/istorage.hpp	100.00% <ø> (ø)
form/storage/storage_file.cpp	100.00% <100.00%> (ø)
form/storage/storage_file.hpp	100.00% <ø> (ø)

... and 2 files with indirect coverage changes

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