AddXmlLanguage.targets

<?xml version="1.0" encoding="utf-8"?>
<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
    <UsingTask TaskName="InjectXmlLanguage" TaskFactory="CodeTaskFactory" AssemblyFile="$(MSBuildToolsPath)\Microsoft.Build.Tasks.Core.dll">
        <ParameterGroup>
            <InputFiles ParameterType="Microsoft.Build.Framework.ITaskItem[]" Required="true" />
        </ParameterGroup>
        <Task>
            <Reference Include="System" />
            <Using Namespace="System.Diagnostics" />
            <Using Namespace="System.IO" />
          <!--
            Not sure where the requirement of xml:lang="en" came from. But to address it - hacking is the only way now:
            https://social.msdn.microsoft.com/forums/en-us/70b984eb-f490-4494-8fbc-12fe4a62e5e4/xmllang-on-doc-for-xml-doc-comments?forum=xmlandnetfx
          -->
            <Code Type="Fragment" Language="cs">
                <![CDATA[
                    Log.LogMessage("Called InjectXmlLanguage");
                    foreach (var inputFilePath in InputFiles.Select(f => f.ItemSpec))
                    {
                        Log.LogMessage("Fixing {0}", inputFilePath);
                        string filePath = inputFilePath;
                        if (filePath.EndsWith(".dll", StringComparison.OrdinalIgnoreCase))
                        {
                            filePath = filePath.Substring(0, filePath.Length - 3) + "xml";
                        }

                        if (filePath.EndsWith(".xml", StringComparison.OrdinalIgnoreCase))
                        {
                            string[] files = null;
                            int starIndex = filePath.IndexOf('*');
                            if (starIndex >= 0)
                            {
                                string dir = filePath.Substring(0, starIndex);
                                if (string.IsNullOrEmpty(dir))
                                {
                                    dir = ".";
                                }

                                string file = Path.GetFileName(filePath.Substring(starIndex));
                                files = Directory.GetFiles(dir, file, SearchOption.AllDirectories);
                            }
                            else
                            {
                                files = new[] { filePath };
                            }

                            foreach (string fileName in files)
                            {
                                if (File.Exists(fileName))
                                {
                                    Log.LogMessage("Processing XML: {0}", fileName);
                                    string text = File.ReadAllText(fileName);
                                    text = text.Replace("<doc>", "<doc xml:lang=\"en\">");
                                    File.WriteAllText(fileName, text);
                                }
                            }
                        }
                    }
                ]]>
            </Code>
        </Task>
    </UsingTask>

    <Target Name="FixXmlDocumentation" AfterTargets="AfterBuild" DependsOnTargets="AfterBuild"  Condition="$(OS) == 'Windows_NT'">
        <InjectXmlLanguage InputFiles="$(DocumentationFile)" />
    </Target>
</Project>