Ensured the system module only contains units from the current run.

Signed-off-by: Dimitar Dobrev <dpldobrev@protonmail.com>

src/AST/Module.cs

@@ -4,8 +4,6 @@ namespace CppSharp.AST
 {
     public class Module
     {
-        public static readonly Module SystemModule = new Module { OutputNamespace = string.Empty, LibraryName = "Std" };
-
         public Module()
         {
             IncludeDirs = new List<string>();

src/Generator/Driver.cs

@@ -434,9 +434,9 @@ namespace CppSharp
                     CompilerOptions = compilerOptions.ToString()
                 };
 
-            if (module != AST.Module.SystemModule)
+            if (module != Options.SystemModule)
                 compilerParameters.ReferencedAssemblies.Add(
-                    string.Format("{0}.dll", AST.Module.SystemModule.LibraryName));
+                    string.Format("{0}.dll", Options.SystemModule.LibraryName));
             // add a reference to System.Core
             compilerParameters.ReferencedAssemblies.Add(typeof(Enumerable).Assembly.Location);
 
@@ -529,7 +529,7 @@ namespace CppSharp
             }
 
             new CleanUnitPass(options).VisitLibrary(driver.ASTContext);
-            options.Modules.RemoveAll(m => m != AST.Module.SystemModule && !m.Units.GetGenerated().Any());
+            options.Modules.RemoveAll(m => m != options.SystemModule && !m.Units.GetGenerated().Any());
 
             if (!options.Quiet)
                 Log.Message("Processing code...");

src/Generator/Generators/CSharp/CSharpTextTemplate.cs

@@ -197,7 +197,8 @@ namespace CppSharp.Generators.CSharp
             }
             PopBlock(NewLineKind.BeforeNextBlock);
 
-            var module = TranslationUnits.Count == 0 ? Module.SystemModule : TranslationUnit.Module;
+            var module = TranslationUnits.Count == 0 ?
+                Driver.Options.SystemModule : TranslationUnit.Module;
             if (!string.IsNullOrEmpty(module.OutputNamespace))
             {
                 PushBlock(CSharpBlockKind.Namespace);
@@ -3131,7 +3132,7 @@ namespace CppSharp.Generators.CSharp
         private string GetLibraryOf(Declaration declaration)
         {
             if (declaration.TranslationUnit.IsSystemHeader)
-                return Module.SystemModule.TemplatesLibraryName;
+                return Driver.Options.SystemModule.TemplatesLibraryName;
 
             string libName = declaration.TranslationUnit.Module.SharedLibraryName;
 

src/Generator/Options.cs

@@ -27,7 +27,8 @@ namespace CppSharp
 
             OutputDir = Directory.GetCurrentDirectory();
 
-            Modules = new List<Module> { Module.SystemModule };
+            SystemModule = new Module { OutputNamespace = string.Empty, LibraryName = "Std" };
+            Modules = new List<Module> { SystemModule };
 
             GeneratorKind = GeneratorKind.CSharp;
             GeneratePartialClasses = true;
@@ -56,6 +57,7 @@ namespace CppSharp
         /// </summary>
         public bool DryRun;
 
+        public Module SystemModule { get; private set; }
         public List<Module> Modules { get; private set; }
 
         public Module MainModule

src/Generator/Passes/CleanUnitPass.cs

@@ -20,7 +20,7 @@ namespace CppSharp.Passes
 
             if (unit.IsSystemHeader)
             {
-                unit.Module = Module.SystemModule;
+                unit.Module = DriverOptions.SystemModule;
             }
             else
             {

src/Generator/Passes/GenerateTemplatesCodePass.cs

@@ -43,7 +43,7 @@ namespace CppSharp.Passes
             foreach (var module in Driver.Options.Modules.Where(m => templateInstantiations.ContainsKey(m)))
             {
                 var cppBuilder = new StringBuilder();
-                if (module == Module.SystemModule)
+                if (module == Driver.Options.SystemModule)
                     cppBuilder.Append("#include <string>\n");
                 else
                     foreach (var header in module.Headers)