False positive IDE0004 and false negative CS0121 reported by the analyzer when calling certain kind of method overloads

[RedSaltyFish]

Version Used: 4.10.0-2.24124.2 (3059a07)

Steps to Reproduce:

1. Define two overloads as shown below.

void Foo(char[] input)
{
    Console.WriteLine(input);
}

void Foo(string input)
{
    Console.WriteLine(input);
}

2. Call the defined method.

Foo((char[])['h', 'e', 'l', 'l', 'o']);

Diagnostic Id: False positive IDE0004, false negative CS0121 if (char[]) conversion is removed.

Expected Behavior: Analyzer doesn't produce IDE0004 when the code is written as shown above and detects CS0121 when (char[]) conversion is removed.

Actual Behavior: False positive IDE0004 reported by analyzer suggesting (char[]) conversion is redundant. Remove (char[]) conversion and no CS0121 is reported by analyzer, but compiling it results in a CS0121 failure.

[CyrusNajmabadi]

I don't repro this:

@cston @RikkiGibson did something change here?

[RikkiGibson]

Yes I think we now require presence of an applicable Add method for non-empty collection-exprs in order for the conversion to exist via the "classic collection initializers" strategy, which causes the string overload to be non-applicable.

[CyrusNajmabadi]

Ok. I'll add a test actually showing we expect this to work.

[CyrusNajmabadi]

@RedSaltyFish this should go away once you upgrade to a more recent version of C# (which may or may not have been released yet :)).