Bunch of fixes for CA1859

[geeknoid]

• When using the ?? operator, the nullable annotation for the left-hand operand is now erased. This prevents the analyzer suggesting to use a replacement nullable type rather than its non-nullable variation. CA1859 erroneously recommends nullable return type #6413

• We no longer suggest to upgrade the type of a local/field/parameter if the symbol is being used to invoke a method that is an explicit implementation of an interface method. If the user would upgrade the type, the call to that method would no longer work. CA1859 improperly handles explicit interface implementations #6416

• Ensure that we never recommend upgrading the signature of a method that implements an interface method.

• Don't recommend a method to be upgraded if the method is an implementation of a partial method definition. This is because there might be different implementations of the method with conflicting behavior. Note that if you use #if constructs, the diagnostic may still make recommendations that would break your code since the analyzer only knows about the selected #if block. Exclude partial method signatures from CA1859 warnings #6414

• Remove a field-specific optimization that was designed to speed up the analyzer, since it actually broke analysis of fields, yielding bogus analysis results. CA1859 erroneously suggests changing return type to one of multiple possible return types #6411

[codecov]

Codecov Report

Merging #6418 (c9f6684) into main (6ae2683) will decrease coverage by 0.00%.
The diff coverage is 97.77%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6418      +/-   ##
==========================================
- Coverage   96.15%   96.15%   -0.01%     
==========================================
  Files        1365     1365              
  Lines      317448   317494      +46     
  Branches    10263    10269       +6     
==========================================
+ Hits       305230   305273      +43     
+ Misses       9785     9784       -1     
- Partials     2433     2437       +4     

[buyaa-n]

Overall LGTM, thank you! Will wait for the open question resolved before merge

[Youssef1313]

#6411 #6413 #6414 #6416 @geeknoid Are all these issues fixed and can be closed?

[geeknoid]

@Youssef1313 Yes, all these issues were fixed.

[Youssef1313]

Thanks @geeknoid. I went ahead and closed the four issues.