[API] fix shared_ptr self assignments

[Reneg973]

see #3713 (comment)

Fixes # (issue)

Changes

prevent self assignment and self move assignment

Please provide a brief description of the changes here.

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

[Reneg973]

Should I remove the unit test not belonging to this PR? It increases test coverage but I'm not sure whether you want to see it in a different commit!

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.93%. Comparing base (c19bfb6) to head (542b2cc).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
api/include/opentelemetry/nostd/shared_ptr.h	50.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3768      +/-   ##
==========================================
- Coverage   89.95%   89.93%   -0.01%     
==========================================
  Files         225      225              
  Lines        7158     7165       +7     
==========================================
+ Hits         6438     6443       +5     
- Misses        720      722       +2     

Files with missing lines	Coverage Δ
api/include/opentelemetry/nostd/shared_ptr.h	96.88% <50.00%> (-3.12%)	⬇️

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[marcalff]

Should I remove the unit test not belonging to this PR? It increases test coverage but I'm not sure whether you want to see it in a different commit!

Please keep the test, this is fine.

It needs to build in CI, there is a self move warning. Maybe use another variable, like:

ptr4 = std::move(ptr1);

[lalitb]

Should I remove the unit test not belonging to this PR? It increases test coverage but I'm not sure whether you want to see it in a different commit!

Please keep the test, this is fine.

It needs to build in CI, there is a self move warning. Maybe use another variable, like:

ptr4 = std::move(ptr1);

Or if we need to test self-assignment for shared pointer.

ptr1 = ptr1; 

[lalitb]

LGTM once the CI is fixed.

[Reneg973]

It needs to build in CI, there is a self move warning. Maybe use another variable, like:

Another variable won't work, I just could use an alias (reference to ptr1), but I'm not sure it tricks all the modern compilers. It may work for now, but not anymore after compiler update. Could also be fixed by suppressing this compiler warning temporarily (if allowed).
Any tips?

[marcalff]

Any tips?

Sure, just remove the code in the unit tests that does not build, due to the self move warning.

The operator= change in the header is simple enough, it does not absolutely require unit test coverage if this brings complications.

[marcalff]

LGTM, thanks for the fix.