No boxing with string concat in VS2019

[sonnemaf]

Suppose you write the following code

using System;

namespace BoxingDemo {
    class Program {
        static void Main(string[] args) {
            
            double salary = 1200;
            string text = "Salary " + salary;
            
            Console.WriteLine(text);
        }
    }
}

You get a warning that there is boxing on line 8, see screenshot.

This warning is correct if you compile your code in Visual Studio 2017. But the compiler has changed in 2019. I examined the IL code in SharpLab,io and you don't get any boxing any more. The value type is first converted to a string using ToString() (IL line 12) and then concatenated (IL line 17).

I think this warning is in Visual Studio 2019 incorrect.

BTW: I love the tool.

[cezarypiatek]

This kind of problem has been discussed in #8