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Unable to get Source Generator to do anything

I've been wrestling with Source Generators but there's a lack of tutorials and information that are hurting.
I want to generate some C# classes from a database. Using a T4 template to do this is difficult and problematic, because of issues I'm having with using SQL in T4 templates and similar.
The description of Source Generator is that "The generator can create new C# source files on the fly that are added to the user's compilation. In this way, you have code that runs during compilation. It inspects your program to produce additional source files that are compiled together with the rest of your code." which seems to match what I want.
This seems significantly more promising.
I've created a project, and put a [Generator] into it using this tutorial.
Full source:
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.Text;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace x
{
[Generator]
internal class TestGenerator : ISourceGenerator
{
public void Execute(GeneratorExecutionContext context)
{
File.Create(#"C:\temp\ITRUNS.TXT");
var sourceBuilder = new StringBuilder(#"
using System;
namespace HelloWorldGenerated
{
public static class HelloWorld
{
public static void SayHello()
{
Console.WriteLine(""Hello from generated code!"");
Console.WriteLine(""The following syntax trees existed in the compilation that created this program:"");
");
Debugger.Launch();
// using the context, get a list of syntax trees in the users compilation
var syntaxTrees = context.Compilation.SyntaxTrees;
// add the filepath of each tree to the class we're building
foreach (SyntaxTree tree in syntaxTrees)
{
sourceBuilder.AppendLine($#"Console.WriteLine(#"" - {tree.FilePath}"");");
}
// finish creating the source to inject
sourceBuilder.Append(#"
}
}
}");
// inject the created source into the users compilation
context.AddSource("helloWorldGenerator", SourceText.From(sourceBuilder.ToString(), Encoding.UTF8));
}
public void Initialize(GeneratorInitializationContext context)
{
}
}
}
I want this to run when I build the solution and create some .cs files
However, it does not run. I put some code in the execute method to create a file, and it does not create the file.
The tutorial says:
Add the source generator from a project as an analyzer and add preview to the LangVersion to the project file like this:
I don't really know what this means. Which project? I tried to download the samples as suggested, but I can't get them to build.
When I examine the code, it's quite hard to understand what they've done that is different.
And what they say in the tutorial about adding the analyzer, doesn't seem to present anywhere in the sample code!
I tried adding the project reference in the csproj that it said to add, however that didn't work - it did create an item within Analyzers but it just has a red - and says 'Ignored' on the tooltip.
I honestly don't know what else I can do to figure out how to get this to work.
I also don't know for sure if it will do what I want - autogenerate a bunch of .cs files with code in that I can use.
I'm going to give it one more go then I'll just write a console application to do it manually instead. Any ideas are welcome.

How to use referenced c# dll code in a VS C# console application

So I have two dlls, Algorithms.dll and Data_Structures.dll (I made these from projects I found on GitHub). Using the browse feature I have managed to add both of the DLL files as references to my Visual Studio 2017 console project. The problem is I can't do anything else with them. Whenever I try to reference something within either file, it simply cannot be found. The only thing that is recognized is the namespace, but nothing inside of that.
What do I need to do to get VS to find the classes these DLLs contain so I can use them? I am aware I need to use Algorithms.Sorting for the example but I can't call anything so I used this as an example.
P.S. If you need more info, please ask. I'm not sure what's relevant to this issue.
EDIT: Ok, it was misleading to have that kind of example. Corrected but please read the question.
EDIT: I tried this on Monodevelop and get the same issue. Maybe it's not the IDE that's the problem?
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Algorithms.Sorting; // Error, Sorting cannot be found, and neither can the file container Sorting
using Data_Structures; //Perfectly ok, can find the namespace
namespace CS_HW2_Testing_App
{
class Program
{
static void Main(string[] args)
{
// I'd like to call MergeSort and so forth here. What am I missing?!
}
}
}
Here's the top piece of the file containing MergeSort if it helps
using System;
using System.Collections.Generic;
using Algorithms.Common;
namespace Algorithms.Sorting
{
public static class MergeSorter
{
//
// Public merge-sort API
public static List<T> MergeSort<T>(this List<T> collection, Comparer<T> comparer = null)
{
comparer = comparer ?? Comparer<T>.Default;
return InternalMergeSort(collection, 0, collection.Count - 1, comparer);
}
...

In the first code block, you're importing the wrong namespace: using Algorithms.MergeSort should be using Algorithms.Sorting. Then you can use MergeSorter.MergeSort<T>(...) in your code!

You need to reference the namespace not the class.
using Algorithms.Sorting; //instead of using Algorithms.MergeSort;
Plus make sure the classes are public

How can I detect unused imports in a Script (rather than a Document) with Roslyn?

I'm writing a system to process snippets written as unit tests for Noda Time, so I can include the snippets in the documentation. I've got a first pass working, but I wanted to tidy up the code. One of the things this needs to do when processing a snippet is work out which of the using directives are actually required for that snippet. (There can be multiple snippets in a single source file, but each snippet will appear separately in the documentation - I don't want imports from one snippet affecting another.)
The working code deals with Document instances - I create a separate Document per snippet containing a single method and all the potential imports, add it to the project, and then remove unnecessary using directives like this:
private async static Task<Document> RemoveUnusedImportsAsync(Document document)
{
var compilation = await document.Project.GetCompilationAsync();
var tree = await document.GetSyntaxTreeAsync();
var root = tree.GetRoot();
var unusedImportNodes = compilation.GetDiagnostics()
.Where(d => d.Id == "CS8019")
.Where(d => d.Location?.SourceTree == tree)
.Select(d => root.FindNode(d.Location.SourceSpan))
.ToList();
return document.WithSyntaxRoot(
root.RemoveNodes(unusedImportNodes, SyntaxRemoveOptions.KeepNoTrivia));
}
I've since learned that I could use the IOrganizeImportsService when working with a document, but I'd like to just write it as a Script, as that feels much cleaner in various ways.
Creating the script is easy, so I'd like to just analyze that for unused imports (after some earlier cleanup steps). Here's code I'd hoped would work for a script:
private static Script RemoveUnusedImports(Script script)
{
var compilation = script.GetCompilation();
var tree = compilation.SyntaxTrees.Single();
var root = tree.GetRoot();
var unusedImportNodes = compilation.GetDiagnostics()
.Where(d => d.Id == "CS8019")
.Where(d => d.Location?.SourceTree == tree)
.Select(d => root.FindNode(d.Location.SourceSpan))
.ToList();
var newRoot = root.RemoveNodes(unusedImportNodes, SyntaxRemoveOptions.KeepNoTrivia);
return CSharpScript.Create(newRoot.ToFullString(), script.Options);
}
Unfortunately, that doesn't find any diagnostics at all - they're just not produced in the compilation :(
Here's a short sample app demonstrating that:
using System;
using Microsoft.CodeAnalysis.CSharp.Scripting;
using Microsoft.CodeAnalysis.Scripting;
class Program
{
static void Main(string[] args)
{
string text = #"
using System;
using System.Collections.Generic;
Console.WriteLine(""I only need to use System"");";
Script script = CSharpScript.Create(text);
// Not sure whether this *should* be required, but it doesn't help...
script.Compile();
var compilation = script.GetCompilation();
foreach (var d in compilation.GetDiagnostics())
{
Console.WriteLine($"{d.Id}: {d.GetMessage()}");
}
}
}
Required package: Microsoft.CodeAnalysis.CSharp.Scripting (e.g. v2.1.0)
This produces no output :(
My guess is that this is intended, because scripting usually has different use cases. But is there any way of enabling more diagnostics for scripting purposes? Or is there some alternative way of detecting unused imports in a Script? If not, I'll go back to my Document-based approach - which would be a pity, as everything else seems to work quite nicely with scripts...

As far as I know, the default compilation in the scripting engine doesn't configure diagnostics for anything but syntax errors. Unfortunately the scripting engine only has limited options to configure the underlying compilation yourself.
However, you can probably achieve what you're after by skipping the scripting engine and directly creating the compilation yourself. This is essentially what the script host does behind the scenes with the addition of some of the defaults for the compilation as well as a few fancy things like lifting class declarations. The code to skip the script host and create the compilation yourself would look something like:
using System;
using System.IO;
using System.Reflection;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
class Program
{
static void Main(string[] args)
{
string text = #"
using System;
using System.Collections.Generic;
Console.WriteLine(""I only need to use System"");";
SyntaxTree syntaxTree = CSharpSyntaxTree.ParseText(text, new CSharpParseOptions(kind: SourceCodeKind.Script));
var coreDir = Path.GetDirectoryName(typeof(object).GetTypeInfo().Assembly.Location);
var mscorlib = MetadataReference.CreateFromFile(Path.Combine(coreDir, "mscorlib.dll"));
var options = new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary);
var compilation = CSharpCompilation.Create("MyAssembly")
.AddSyntaxTrees(syntaxTree)
.AddReferences(mscorlib)
.WithOptions(options);
foreach (var d in compilation.GetDiagnostics())
{
Console.WriteLine($"{d.Id}: {d.GetMessage()}");
}
}
}
You'll notice this produces some undesirable diagnostics about missing references and such - the compilation references need to be tweaked a little to include the default libraries (you can see the pattern with mscorlib above). You should see the desired diagnostics about unused using statements as well.

Microsoft Fakes: Trying to shim a class but dependencies are still there

Ok, so here's the deal: I have a complex, heavily dependent class LegacyClass that I'd like to shim so that I get rid of all its dependencies while unit testing other parts of the code base. That class creates dependencies already inside its default constructor, so I need to override it with something with no external dependencies, say, with an empty default constructor. And this is what I'm trying to do (using the Visual Studio 2013 Professional Test Framework):
using System;
using Microsoft.QualityTools.Testing.Fakes;
using Microsoft.VisualStudio.TestTools.UnitTesting;
namespace MyApp_Unit_Tests {
[TestClass]
public class UnitTest1 {
[TestMethod]
public void TestInstantiation1() {
using (ShimsContext.Create()) {
MyNamespace.Fakes.ShimLegacyClass.Constructor = x => { };
var legacyClassInstance = new MyNamespace.Fakes.ShimLegacyClass();
var sut = new MyNamespace.Gui.ViewModels.MainWindowViewModel(legacyClassInstance);
}
}
}
}
However, this does not work. When MainWindowViewModel is instantiated, for some reason all the same external dependencies are still required as with using the original class! Why?
The exception I'm getting, though, is System.BadImageFormatException, so I probably have some confusion about the target CPU settings, too, but anyway the root cause is that it's attempting to load the external DLL referred to only in the original (non-shimmed) legacy class in its default constructor, while I think it no longer should.
Obviously I've been misunderstood, but where's the mistake? Can I not override default constructors, after all, even with using Shims, or is my approach just wrong? What am I missing?
Thanks a million in advance for any advice!
-Seppo

I had same problem and I solved it maybe this approach going to help you
using (ShimsContext.Create())
{
LegacyClass obj=new LegacyClass();
ShimLegacyClass shimobj=new ShimLegacyClass(obj);
//
// modify every thing you want on shimobj
//
shimobj.InstanceBehavior = ShimBehaviors.Fallthrough;
//rest of test
}
This approach helps you to break dependencies in every part you want and keep the rest same as main class

Unable to compile code output because of some reference assembly goofups

My issue goes like this:
There is a project called myframework. It has some extension methods defined in it as follows:
namespace myframework
{
public static class Helpers
{
public static bool ContainsAll(this string obj, string[])
{
return true;
}
}
}
It also has some other stuff like interfaces, etc, etc.
There is a second class I generate via System.CodeDom classes. The generated output is somewhat like this:
using myframework;
public class A: IMyFrameworkInterface
{
public void foo()
{
string s ="HELLO";
if(s.ContainsAll(some_arr))
return;
}
//More methods defined...
}
The compiler options I pass which is created prior to the actual compile call references the correct assemblies
var cp = new CompilerParameters();
cp.ReferencedAssemblies.Add("System.dll");
cp.ReferencedAssemblies.Add("myframework.dll");
The code compilation modules are written in a different project. The particular class responsible for this also nicely gives us access to a list of CompilerError object via which we can learn the result of compilation.
Issue1: When I tried this in an asp.net project the compiler threw error saying it could not find metadata file myframework.dll (despite it being referenced in the project).
Issue2: When I tried it with a windows forms project. It gave a different error. This time saying that string does not contain definition for ContainsAll()
How to solve these two specific problems?

Found out the answer to this after a bit digging up. I was using .net framework 3.5. The codedom compiler apis targets v2.0 of the framework by default. Hence, you have to manually specify the correct framework:
var cp = new CompilerParameters(
new Dictionary<string,string>() { {"CompilerVersion", "v3.5"} });
For the compilation to work within an asp.net environment you'd have to actually point the references to the correct location. Hence you'd have to do something like follows:
cp.ReferencedAssemblies.Add(
HttpContext.Current.Server.MapPath(
"bin\\myframework.dll"));
My references:
http://blogs.msdn.com/b/lukeh/archive/2007/07/11/c-3-0-and-codedom.aspx
.Net 3.5 CodeDom Compiler generating odd errors
And comments in the question's post. :)