When a type implements interface explicitly, then CA1859 gives false positive when th explicit implementation is used through the interface type.

[bharathkolanda]

Analyzer

Diagnostic ID: CA1859: Use concrete types when possible for improved performance

Analyzer source

SDK: Built-in CA analyzers in .NET 5 SDK or later

Version: SDK 8.0.101

Describe the bug

CA1859 is falsely raised when a type implements an interface explicitly. Applying the suggested fix leads to compilation errors.

Steps To Reproduce

interface IFoo
{
bool Attach(IContext context);
}

class SampleHandler : IFoo
{
bool IFoo.Attach(IContext context)
{
....
return true;
}
}

IFoo fooClone = new SampleHandler();
Change type of variable 'fooClone' from 'IFoo' to 'SampleHandler' for improved performance
bool attachResult = fooClone.Attach( workingContext );

Expected behavior

Actual behavior

CA1859 is raised for fooClone.Attach method, suggesting to change the type to SampleHandler.

[YoshiRulz]

I think that's correct? If the implementation in SampleHandler was new then it shouldn't be flagged.