Enabled cleaning up in type maps and used it to dispose of used std::string objects.

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

src/Generator/Generators/CSharp/CSharpMarshal.cs

@@ -31,7 +31,7 @@ namespace CppSharp.Generators.CSharp
 
         public TextGenerator ArgumentPrefix { get; private set; }
         public TextGenerator Cleanup { get; private set; }
-        public bool HasFixedBlock { get; set; }
+        public bool HasCodeBlock { get; set; }
     }
 
     public abstract class CSharpMarshalPrinter : MarshalPrinter<CSharpMarshalContext>
@@ -420,7 +420,7 @@ namespace CppSharp.Generators.CSharp
                             array.Type, ptr, Context.Parameter.Name);
                         Context.SupportBefore.WriteStartBraceIndent();
                         Context.Return.Write("new global::System.IntPtr({0})", ptr);
-                        Context.HasFixedBlock = true;
+                        Context.HasCodeBlock = true;
                     }
                     else
                     {
@@ -495,7 +495,7 @@ namespace CppSharp.Generators.CSharp
                 var refParamPtr = string.Format("__refParamPtr{0}", Context.ParameterIndex);
                 Context.SupportBefore.WriteLine("fixed ({0} {1} = &{2})",
                     pointer, refParamPtr, Context.Parameter.Name);
-                Context.HasFixedBlock = true;
+                Context.HasCodeBlock = true;
                 Context.SupportBefore.WriteStartBraceIndent();
                 Context.Return.Write(refParamPtr);
                 return true;

src/Generator/Generators/CSharp/CSharpTextTemplate.cs

@@ -955,6 +955,7 @@ namespace CppSharp.Generators.CSharp
 
                 ctx.Kind = CSharpMarshalKind.NativeField;
                 var marshal = new CSharpMarshalManagedToNativePrinter(ctx);
+                ctx.Declaration = field;
 
                 var arrayType = field.Type as ArrayType;
 
@@ -977,6 +978,9 @@ namespace CppSharp.Generators.CSharp
                 if (!string.IsNullOrWhiteSpace(marshal.Context.SupportBefore))
                     Write(marshal.Context.SupportBefore);
 
+                if (ctx.HasCodeBlock)
+                    PushIndent();
+
                 if (marshal.Context.Return.StringBuilder.Length > 0)
                 {
                     WriteLine("{0} = {1}{2};", ctx.ReturnVarName,
@@ -986,7 +990,7 @@ namespace CppSharp.Generators.CSharp
                         marshal.Context.Return);
                 }
 
-                if (arrayType != null && @class.IsValueType)
+                if ((arrayType != null && @class.IsValueType) || ctx.HasCodeBlock)
                     WriteCloseBraceIndent();
 
                 WriteCloseBraceIndent();
@@ -1109,6 +1113,7 @@ namespace CppSharp.Generators.CSharp
                 {
                     Kind = CSharpMarshalKind.NativeField,
                     ArgName = decl.Name,
+                    Declaration = decl,
                     ReturnVarName = string.Format("{0}{1}{2}",
                         @class.IsValueType
                             ? Helpers.InstanceField
@@ -1129,6 +1134,9 @@ namespace CppSharp.Generators.CSharp
                 if (!string.IsNullOrWhiteSpace(marshal.Context.SupportBefore))
                     Write(marshal.Context.SupportBefore);
 
+                if (ctx.HasCodeBlock)
+                    PushIndent();
+
                 var @return = marshal.Context.Return.ToString();
                 if (field.Type.IsPointer())
                 {
@@ -1139,7 +1147,7 @@ namespace CppSharp.Generators.CSharp
                 }
                 WriteLine("return {0};", @return);
 
-                if (arrayType != null && @class.IsValueType)
+                if ((arrayType != null && @class.IsValueType) || ctx.HasCodeBlock)
                     WriteCloseBraceIndent();
             }
             else if (decl is Variable)
@@ -2744,6 +2752,9 @@ namespace CppSharp.Generators.CSharp
                 if (!string.IsNullOrWhiteSpace(marshal.Context.SupportBefore))
                     Write(marshal.Context.SupportBefore);
 
+                if (ctx.HasCodeBlock)
+                    PushIndent();
+
                 // Special case for indexer - needs to dereference if the internal
                 // function is a pointer type and the property is not.
                 if (retType.Type.IsAddress() &&
@@ -2752,12 +2763,15 @@ namespace CppSharp.Generators.CSharp
                     WriteLine("return *{0};", marshal.Context.Return);
                 else
                     WriteLine("return {0};", marshal.Context.Return);
+
+                if (ctx.HasCodeBlock)
+                    WriteCloseBraceIndent();
             }
 
             if (needsFixedThis && operatorParam == null)
                 WriteCloseBraceIndent();
             
-            var numFixedBlocks = @params.Count(param => param.HasFixedBlock);
+            var numFixedBlocks = @params.Count(param => param.HasUsingBlock);
             for(var i = 0; i < numFixedBlocks; ++i)
                 WriteCloseBraceIndent();
         }
@@ -2838,7 +2852,7 @@ namespace CppSharp.Generators.CSharp
             public string Name;
             public Parameter Param;
             public CSharpMarshalContext Context;
-            public bool HasFixedBlock;
+            public bool HasUsingBlock;
         }
 
         public List<ParamMarshal> GenerateFunctionParamsMarshal(IEnumerable<Parameter> @params,
@@ -2896,7 +2910,7 @@ namespace CppSharp.Generators.CSharp
             paramMarshal.Context = ctx;
             var marshal = new CSharpMarshalManagedToNativePrinter(ctx);
             param.CSharpMarshalToNative(marshal);
-            paramMarshal.HasFixedBlock = ctx.HasFixedBlock;
+            paramMarshal.HasUsingBlock = ctx.HasCodeBlock;
 
             if (string.IsNullOrEmpty(marshal.Context.Return))
                 throw new Exception("Cannot marshal argument of function");
@@ -2904,7 +2918,7 @@ namespace CppSharp.Generators.CSharp
             if (!string.IsNullOrWhiteSpace(marshal.Context.SupportBefore))
                 Write(marshal.Context.SupportBefore);
 
-            if (paramMarshal.HasFixedBlock)
+            if (paramMarshal.HasUsingBlock)
                 PushIndent();
 
             WriteLine("var {0} = {1};", argName, marshal.Context.Return);

src/Generator/Types/Std/Stdlib.cs

@@ -57,9 +57,10 @@ namespace CppSharp.Types.Std
             return basicString.Visit(typePrinter).Type;
         }
 
-        public override void CSharpMarshalToNative(MarshalContext ctx)
+        public override void CSharpMarshalToNative(CSharpMarshalContext ctx)
         {
-            ClassTemplateSpecialization basicString = GetBasicString(ctx.Parameter.Type);
+            var type = ctx.Parameter.Type.Desugar();
+            ClassTemplateSpecialization basicString = GetBasicString(type);
             var typePrinter = new CSharpTypePrinter(ctx.Driver);
             typePrinter.PushContext(CSharpTypePrinterContextKind.Native);
             if (!ctx.Parameter.Type.Desugar().IsAddress())
@@ -67,19 +68,46 @@ namespace CppSharp.Types.Std
             typePrinter.PopContext();
             var allocator = ctx.Driver.ASTContext.FindClass("allocator", false, true).First(
                 a => a.IsSupportedStdType());
-            ctx.Return.Write("new {0}({1}, new {2}()).{3}",
-                basicString.Visit(typePrinter), ctx.Parameter.Name,
-                allocator.Visit(typePrinter), Helpers.InstanceIdentifier);
+            if (type.IsPointer() || (type.IsReference() && ctx.Declaration is Field))
+            {
+                ctx.Return.Write("new {0}({1}, new {2}()).{3}",
+                    basicString.Visit(typePrinter), ctx.Parameter.Name,
+                    allocator.Visit(typePrinter), Helpers.InstanceIdentifier);
+            }
+            else
+            {
+                string varBasicString = "__basicString" + ctx.ParameterIndex;
+                ctx.SupportBefore.WriteLine("using (var {0} = new {1}({2}, new {3}()))",
+                    varBasicString, basicString.Visit(typePrinter),
+                    ctx.Parameter.Name, allocator.Visit(typePrinter));
+                ctx.SupportBefore.WriteStartBraceIndent();
+                ctx.Return.Write("{0}.{1}", varBasicString, Helpers.InstanceIdentifier);
+                ctx.HasCodeBlock = true;
+            }
         }
 
-        public override void CSharpMarshalToManaged(MarshalContext ctx)
+        public override void CSharpMarshalToManaged(CSharpMarshalContext ctx)
         {
-            ClassTemplateSpecialization basicString = GetBasicString(ctx.ReturnType.Type);
+            var type = ctx.ReturnType.Type;
+            ClassTemplateSpecialization basicString = GetBasicString(type);
             var c_str = basicString.Methods.First(m => m.OriginalName == "c_str");
             var typePrinter = new CSharpTypePrinter(ctx.Driver);
-            ctx.Return.Write("{0}.{1}({2}).{3}()",
-                basicString.Visit(typePrinter), Helpers.CreateInstanceIdentifier,
-                ctx.ReturnVarName, c_str.Name);
+            if (type.IsPointer() || ctx.Declaration is Field)
+            {
+                ctx.Return.Write("{0}.{1}({2}).{3}()",
+                    basicString.Visit(typePrinter), Helpers.CreateInstanceIdentifier,
+                    ctx.ReturnVarName, c_str.Name);
+            }
+            else
+            {
+                const string varBasicString = "__basicStringRet";
+                ctx.SupportBefore.WriteLine("using (var {0} = {1}.{2}({3}))",
+                    varBasicString, basicString.Visit(typePrinter),
+                    Helpers.CreateInstanceIdentifier, ctx.ReturnVarName);
+                ctx.SupportBefore.WriteStartBraceIndent();
+                ctx.Return.Write("{0}.{1}()", varBasicString, c_str.Name);
+                ctx.HasCodeBlock = true;
+            }
         }
 
         private static ClassTemplateSpecialization GetBasicString(Type type)
@@ -114,12 +142,12 @@ namespace CppSharp.Types.Std
             return "string";
         }
 
-        public override void CSharpMarshalToNative(MarshalContext ctx)
+        public override void CSharpMarshalToNative(CSharpMarshalContext ctx)
         {
             ctx.Return.Write("new Std.WString()");
         }
 
-        public override void CSharpMarshalToManaged(MarshalContext ctx)
+        public override void CSharpMarshalToManaged(CSharpMarshalContext ctx)
         {
             ctx.Return.Write(ctx.ReturnVarName);
         }
@@ -257,12 +285,12 @@ namespace CppSharp.Types.Std
             return string.Format("Std.Vector<{0}>", ctx.GetTemplateParameterList());
         }
 
-        public override void CSharpMarshalToNative(MarshalContext ctx)
+        public override void CSharpMarshalToNative(CSharpMarshalContext ctx)
         {
             ctx.Return.Write("{0}.Internal", ctx.Parameter.Name);
         }
 
-        public override void CSharpMarshalToManaged(MarshalContext ctx)
+        public override void CSharpMarshalToManaged(CSharpMarshalContext ctx)
         {
             var templateType = Type as TemplateSpecializationType;
             var type = templateType.Arguments[0].Type;
@@ -382,12 +410,12 @@ namespace CppSharp.Types.Std
             return CSharpTypePrinter.IntPtrType;
         }
 
-        public override void CSharpMarshalToNative(MarshalContext ctx)
+        public override void CSharpMarshalToNative(CSharpMarshalContext ctx)
         {
             ctx.Return.Write(ctx.Parameter.Name);
         }
 
-        public override void CSharpMarshalToManaged(MarshalContext ctx)
+        public override void CSharpMarshalToManaged(CSharpMarshalContext ctx)
         {
             ctx.Return.Write(ctx.ReturnVarName);
         }

src/Generator/Types/TypeMap.cs

@@ -67,12 +67,12 @@ namespace CppSharp.Types
             throw new NotImplementedException();
         }
 
-        public virtual void CSharpMarshalToNative(MarshalContext ctx)
+        public virtual void CSharpMarshalToNative(CSharpMarshalContext ctx)
         {
             throw new NotImplementedException();
         }
 
-        public virtual void CSharpMarshalToManaged(MarshalContext ctx)
+        public virtual void CSharpMarshalToManaged(CSharpMarshalContext ctx)
         {
             throw new NotImplementedException();
         }

tests/CSharp/CSharp.cs

@@ -29,7 +29,7 @@ namespace CppSharp.Tests
             return CSharpSignatureType(ctx).ToString();
         }
 
-        public override void CSharpMarshalToNative(MarshalContext ctx)
+        public override void CSharpMarshalToNative(CSharpMarshalContext ctx)
         {
             if (ctx.Parameter.Type.Desugar().IsAddress())
                 ctx.Return.Write("new global::System.IntPtr(&{0})", ctx.Parameter.Name);
@@ -37,7 +37,7 @@ namespace CppSharp.Tests
                 ctx.Return.Write(ctx.Parameter.Name);
         }
 
-        public override void CSharpMarshalToManaged(MarshalContext ctx)
+        public override void CSharpMarshalToManaged(CSharpMarshalContext ctx)
         {
             if (ctx.ReturnType.Type.Desugar().IsAddress())
             {
@@ -89,13 +89,13 @@ namespace CppSharp.Tests
                 ctx.GetTemplateParameterList());
         }
 
-        public override void CSharpMarshalToNative(MarshalContext ctx)
+        public override void CSharpMarshalToNative(CSharpMarshalContext ctx)
         {
             // pointless, put just so that the generated code compiles
             ctx.Return.Write("new QList.Internal()");
         }
 
-        public override void CSharpMarshalToManaged(MarshalContext ctx)
+        public override void CSharpMarshalToManaged(CSharpMarshalContext ctx)
         {
             ctx.Return.Write(ctx.ReturnVarName);
         }
@@ -110,12 +110,12 @@ namespace CppSharp.Tests
             return "int";
         }
 
-        public override void CSharpMarshalToNative(MarshalContext ctx)
+        public override void CSharpMarshalToNative(CSharpMarshalContext ctx)
         {
             ctx.Return.Write(ctx.Parameter.Name);
         }
 
-        public override void CSharpMarshalToManaged(MarshalContext ctx)
+        public override void CSharpMarshalToManaged(CSharpMarshalContext ctx)
         {
             ctx.Return.Write(ctx.ReturnVarName);
         }

tests/Common/Common.Tests.cs

@@ -407,11 +407,9 @@ public class CommonTests : GeneratorTestFixture
     public void TestVariable()
     {
         // Test field property
-        // HACK: disabled until https://github.com/mono/CppSharp/issues/675 is fixed.
-        // It used to work thanks to a hack in Common.cs which is now removed because it caused problems with system types
-        //var @var = new TestVariables();
-        //@var.Value = 10;
-        //Assert.That(TestVariables.VALUE, Is.EqualTo(10));
+        var @var = new TestVariables();
+        @var.Value = 10;
+        Assert.That(TestVariables.VALUE, Is.EqualTo(10));
     }
 
     [Test]
@@ -635,6 +633,18 @@ public class CommonTests : GeneratorTestFixture
         }
     }
 
+    // ignored until we add automatic compilation for templates
+    [Test, Ignore]
+    public void TestStdString()
+    {
+        using (var hasStdString = new HasStdString())
+        {
+            Assert.That(hasStdString.testStdString("test"), Is.EqualTo("test_test"));
+            hasStdString.s = "test";
+            Assert.That(hasStdString.s, Is.EqualTo("test"));
+        }
+    }
+
     private class CustomDerivedFromVirtual : AbstractWithVirtualDtor
     {
         public override void @abstract()

tests/Common/Common.cs

@@ -32,12 +32,12 @@ namespace CppSharp.Tests
             return "ushort";
         }
 
-        public override void CSharpMarshalToManaged(MarshalContext ctx)
+        public override void CSharpMarshalToManaged(CSharpMarshalContext ctx)
         {
             ctx.Return.Write(ctx.ReturnVarName);
         }
 
-        public override void CSharpMarshalToNative(MarshalContext ctx)
+        public override void CSharpMarshalToNative(CSharpMarshalContext ctx)
         {
             ctx.Return.Write("IntPtr.Zero");
         }