"IDE0305 Use collection expression for fluent" not raised if ToArray() is assigned to a var variable

[Piedone]

Analyzer

Diagnostic ID: IDE0305: Use collection expression for fluent

Analyzer source

NuGet Package: Microsoft.CodeAnalysis.CSharp.CodeStyle

Version: 4.9.2

Describe the bug

Steps To Reproduce

1. Use the following code:

var list = new List<string>
{
    "one",
    "two",
    "three"
};

var array = list.ToArray();

foreach (var item in array)
{
    Console.WriteLine(item);
}

2. Observe that var array = list.ToArray(); line does NOT violate IDE0305.
3. Try the code modified as follows:

List<string> list =
[
    "one",
    "two",
    "three",
];

string[] array = list.ToArray();

foreach (string item in array)
{
    Console.WriteLine(item);
}

4. Observe that string[] array = list.ToArray(); does violate IDE0305.

Expected behavior

Both versions violate IDE0305.

Actual behavior

Only the non-var version violates IDE0305.

Additional context

Full source available here. The offending code is in the root Program.

#73639 might be related.

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[CyrusNajmabadi]

This is by design. Collection expressions have no natural type, and so cannot be used with var.