You cannot have literals in a T4 template after a scriptlet.

Change

<#@ template debug="true" language="C#" #> <#+ // scriptlet #> <-- empty line here 

To

<#@ template debug="true" language="C#" #> <#+ // scriptlet #> 

Debugging

You can see the C# being generated by the T4 engine by calling PreProcessTemplate with a custom templating host.

I modified the Custom Template Host sample for this purpose:

using Microsoft.VisualStudio.TextTemplating; using System; using System.CodeDom.Compiler; using System.Collections.Generic; using System.IO; using System.Text; namespace CustomHost { class CustomCmdLineHost : ITextTemplatingEngineHost { public string TemplateFile { get; private set; } public string FileExtension { get; private set; } public Encoding FileEncoding { get; private set; } public CompilerErrorCollection Errors { get; private set; } public IList<string> StandardAssemblyReferences { get { return new[] { typeof(System.Uri).Assembly.Location }; } } public IList<string> StandardImports { get { return new string[] { "System" }; } } public CustomCmdLineHost(string file) { this.TemplateFile = file; this.FileEncoding = Encoding.UTF8; this.FileExtension = ".txt"; } public bool LoadIncludeText(string requestFileName, out string content, out string location) { content = location = String.Empty; if (File.Exists(requestFileName)) { content = File.ReadAllText(requestFileName); return true; } return false; } public object GetHostOption(string optionName) { object returnObject; switch (optionName) { case "CacheAssemblies": returnObject = true; break; default: returnObject = null; break; } return returnObject; } public string ResolveAssemblyReference(string assemblyReference) { return ResolvePath(assemblyReference); } public Type ResolveDirectiveProcessor(string processorName) { throw new Exception("Directive Processor not found"); } public string ResolvePath(string fileName) { if (File.Exists(fileName)) { return fileName; } string candidate = Path.Combine(Path.GetDirectoryName(this.TemplateFile), fileName); if (File.Exists(candidate)) { return candidate; } return fileName; } public string ResolveParameterValue(string directiveId, string processorName, string parameterName) { return String.Empty; } public void SetFileExtension(string extension) { FileExtension = extension; } public void SetOutputEncoding(System.Text.Encoding encoding, bool fromOutputDirective) { FileEncoding = encoding; } public void LogErrors(CompilerErrorCollection errors) { Errors = errors; } public AppDomain ProvideTemplatingAppDomain(string content) { return AppDomain.CreateDomain("Generation App Domain"); } } class Program { static void Main(string[] args) { var templateFileName = args[0]; CustomCmdLineHost host = new CustomCmdLineHost(templateFileName); Engine engine = new Engine(); string language; string[] refs; var output = engine.PreprocessTemplate( // input file File.ReadAllText(templateFileName), host, "testClass", "testNamespace", out language, out refs); string outputFileName = Path.Combine( Path.GetDirectoryName(templateFileName), templateFileName + ".generator.cs"); File.WriteAllText(outputFileName, output, host.FileEncoding); foreach (CompilerError error in host.Errors) Console.WriteLine(error.ToString()); Console.ReadLine(); } } } 

Examining the transformer generated from the template showed lines like the following outside the TransformText() method. Seemingly, any literals in the source templates which came after a scriptlet (<#+ #>) would be placed in-fix into the generated generator class.

 #line 1 "C:\dev\ImmutableObjectGraph-master\2013\Demo\Fruit.tt" this.Write("\n"); 

Removing the newline characters at the end of each template file resolved the issue.