Get parse errors from string.

gistfile1.cs

using System;
using System.Collections;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.Text;

class Program
{
	static void Main(string[] args)
	{
		var tree = CSharpSyntaxTree.ParseText(SourceText.From("class a{}"));
		var compilation = CSharpCompilation.Create("test", new[] { tree });
		compilation = compilation.AddReferences(
			MetadataReference.CreateFromAssembly(typeof(object).Assembly),
			MetadataReference.CreateFromAssembly(typeof(IEnumerable).Assembly));
		var diagnostics = compilation.GetParseDiagnostics();
		foreach (var diagnostic in diagnostics)
		{
			Console.WriteLine(diagnostic);
		}
	}
}