Number scale helper function

[ximinez]

High Level Overview of Change

After looking again at #6246 changes, I realized there could be a simpler function call.

Questions:

1. Is this worth merging?
2. If it is worth merging, is numberScale a good name?
3. Also if it's worth merging, would it be worth getting rid of Number::scale entirely and inlining it into numberScale?

Context of Change

• Add canonical "scale" computation to Number #6246

Type of Change

• Refactor (non-breaking change that only restructures code)

[codecov]

Codecov Report

❌ Patch coverage is 66.66667% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.8%. Comparing base (253c04b) to head (651d4ee).
⚠️ Report is 1 commits behind head on tapanito/lending-vault-invariant.

Files with missing lines	Patch %	Lines
src/libxrpl/tx/InvariantCheck.cpp	50.0%	6 Missing ⚠️

Additional details and impacted files

@@                       Coverage Diff                        @@
##           tapanito/lending-vault-invariant   #6384   +/-   ##
================================================================
  Coverage                              79.8%   79.8%           
================================================================
  Files                                   846     846           
  Lines                                 67825   67825           
  Branches                               7556    7557    +1     
================================================================
  Hits                                  54130   54130           
  Misses                                13695   13695           

Files with missing lines	Coverage Δ
include/xrpl/basics/Number.h	98.7% <ø> (-<0.1%)	⬇️
include/xrpl/protocol/STAmount.h	95.7% <100.0%> (+0.1%)	⬆️
...clude/xrpl/tx/transactors/Lending/LendingHelpers.h	95.2% <100.0%> (ø)
...tx/transactors/Lending/LoanBrokerCoverWithdraw.cpp	96.3% <100.0%> (ø)
src/libxrpl/tx/InvariantCheck.cpp	93.0% <50.0%> (ø)

... and 5 files with indirect coverage changes

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[Copilot]

Pull request overview

Refactors “Number scale” computation by replacing the recently added Number::scale member template with a simpler free helper function, and updates vault/lending call sites to use it.

Changes:

• Add scale(Number const&, Asset const&) helper in STAmount.h.
• Remove Number::scale (and its supporting concept) from Number.h.
• Update invariant checks and lending/vault-related code/tests to call the new helper (plus minor formatting-only changes).

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/test/app/Vault_test.cpp	Formatting-only adjustment to lambda parameter layout.
src/test/app/Invariants_test.cpp	Switches vault min-scale test helper to scale(number, asset).
src/libxrpl/tx/transactors/Lending/LoanBrokerCoverWithdraw.cpp	Uses new scale(...) helper when rounding minimum cover.
src/libxrpl/tx/InvariantCheck.cpp	Uses new scale(...) helper for vault delta scale computations.
include/xrpl/tx/transactors/Lending/LendingHelpers.h	Uses new scale(...) helper to compute stored assets-total scale.
include/xrpl/protocol/STAmount.h	Adds the new scale(Number, Asset) helper and minor formatting of operators.
include/xrpl/basics/Number.h	Removes Number::scale member template and related concept.

Comments suppressed due to low confidence (2)

include/xrpl/protocol/STAmount.h:726

• The new doc comment for scale(Number, Asset) has very long lines and a slightly awkward sentence (“different rules and mantissa ranges for determining the exponent than Number”). Please wrap to match the surrounding style and tweak the wording for clarity/grammar.

/** Get the scale of a Number for a given asset.
 *
 * "scale" is similar to "exponent", but from the perspective of STAmount, which has different rules and mantissa ranges
 * for determining the exponent than Number.

src/libxrpl/tx/InvariantCheck.cpp:3012

• The std::max(scale(...), scale(...)) initializer is now formatted on a single long line, while the adjacent availableDelta uses a wrapped style. Consider wrapping this call too for consistency/readability (and to avoid line-length issues).

                        afterVault.assetsTotal - beforeVault.assetsTotal,
                        std::max(
                            scale(afterVault.assetsTotal, vaultAsset), scale(beforeVault.assetsTotal, vaultAsset))};
                    DeltaInfo availableDelta{

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[Tapanito]

Out of scope for this PR, but do we still need these blocks? Can we clean them up?

[ximinez]

Out of scope for this PR, but do we still need these blocks? Can we clean them up?

That #if block is wrapped around test cases that I started or copy/pasted, but wasn't able to fully integrate and get working - not Loan problems, but just problems with the way the test was written or the scenario was set up. I think it would be worthwhile to come back to them eventually. I could stick them in a branch, but they're likely to be even more forgotten than they are now.

I only renamed the label because cspell complained about it, and I want a green build.