The Diagnostics property provides a collection of diagnostic messages, including warnings and errors, that were generated during the last build process. This property is useful for analyzing and debugging the build process by examining the issues that occurred.

To access the diagnostics from the last build, you can use the Diagnostics property of the Compiler class. This property returns an array of Microsoft.CodeAnalysis.Diagnostic objects, each representing a specific issue encountered during the build.

Example usage:

var compiler = new Compiler();
var diagnostics = compiler.Diagnostics;

foreach (var diagnostic in diagnostics)
{
    Console.WriteLine($"{diagnostic.Id}: {diagnostic.GetMessage()}");
}