Add policy based free functions for signed integers

[mborland]

Closes: #131

[cppalliance-bot]

An automated preview of the documentation is available at https://167.safe-numbers.prtest3.cppalliance.org/libs/safe_numbers/doc/html/index.html

If more commits are pushed to the pull request, the docs will rebuild at the same URL.

2026-04-07 20:50:08 UTC

[codecov]

Codecov Report

❌ Patch coverage is 97.41379% with 24 lines in your changes missing coverage. Please review.
✅ Project coverage is 97.1%. Comparing base (77df19f) to head (e7b1876).
⚠️ Report is 7 commits behind head on develop.

Files with missing lines	Patch %	Lines
...boost/safe_numbers/detail/signed_integer_basis.hpp	88.9%	22 Missing ⚠️
test/test_signed_saturating_division.cpp	97.7%	1 Missing ⚠️
test/test_signed_saturating_mod.cpp	97.7%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##           develop    #167     +/-   ##
=========================================
+ Coverage     96.9%   97.1%   +0.3%     
=========================================
  Files          121     141     +20     
  Lines         9356   10264    +908     
  Branches      3537    3720    +183     
=========================================
+ Hits          9058    9962    +904     
- Misses         232     236      +4     
  Partials        66      66             

Files with missing lines	Coverage Δ
include/boost/safe_numbers/detail/type_traits.hpp	100.0% <ø> (ø)
test/test_signed_checked_addition.cpp	100.0% <100.0%> (ø)
test/test_signed_checked_division.cpp	100.0% <100.0%> (ø)
test/test_signed_checked_mod.cpp	100.0% <100.0%> (ø)
test/test_signed_checked_multiplication.cpp	100.0% <100.0%> (ø)
test/test_signed_checked_subtraction.cpp	100.0% <100.0%> (ø)
test/test_signed_overflowing_addition.cpp	100.0% <100.0%> (ø)
test/test_signed_overflowing_division.cpp	100.0% <100.0%> (ø)
test/test_signed_overflowing_mod.cpp	100.0% <100.0%> (ø)
test/test_signed_overflowing_multiplication.cpp	100.0% <100.0%> (ø)
... and 12 more

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 77df19f...e7b1876. Read the comment docs.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.