What does "File has no header" build warning in visual studio mean

Question

I'm building my project fine but two of the files in my unit test project give a build warning "File has no header." they're unrelated and otherwise unremarkable .cs files. I've googled but get swamped with results for "SA1633: The file has no header, the header Xml is invalid, or the header is not ...."

These warnings do not have an error code, what could they mean?

Answer 1

That´s a StyleCop code analysis violation.

This means that a C# source file is missing a file header.

The file header must begin on the first line of the file and must be formatted as a block of comments containing Xml, as follows:

//-----------------------------------------------------------------------
// <copyright file="NameOfFile.cs" company="CompanyName">
//     Company copyright tag.
// </copyright>
//-----------------------------------------------------------------------