Resolve names matching those of system functions

Fixes https://github.com/mono/CppSharp/issues/1602.

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

src/Generator/Generators/C/CCodeGenerator.cs

@@ -152,7 +152,7 @@ namespace CppSharp.Generators.C
             if (IsCLIGenerator)
             {
                 if (@enum.Modifiers.HasFlag(Enumeration.EnumModifiers.Flags))
-                    WriteLine("[System::Flags]");
+                    WriteLine("[::System::Flags]");
 
                 // A nested class cannot have an assembly access specifier as part
                 // of its declaration.

src/Generator/Generators/C/CppMarshal.cs

@@ -272,7 +272,7 @@ namespace CppSharp.Generators.Cpp
                 Context.Return.Write($"({instance} == nullptr) ? nullptr : {MemoryAllocOperator} ");
 
             Context.Return.Write($"{QualifiedIdentifier(@class)}(");
-            Context.Return.Write($"(::{@class.QualifiedOriginalName}*)");
+            Context.Return.Write($"({(@class.IsUnion ? "union" : "struct")} ::{@class.QualifiedOriginalName}*)");
             Context.Return.Write($"{instance})");
         }
 
@@ -409,7 +409,7 @@ namespace CppSharp.Generators.Cpp
                     Context.Parameter.Usage == ParameterUsage.InOut;
 
                 Context.ArgumentPrefix.Write("&");
-                Context.Return.Write($"(::{@enum.QualifiedOriginalName}){0}{Context.Parameter.Name}",
+                Context.Return.Write($"(enum ::{@enum.QualifiedOriginalName}){0}{Context.Parameter.Name}",
                     isRef ? string.Empty : "*");
                 return true;
             }
@@ -511,7 +511,7 @@ namespace CppSharp.Generators.Cpp
             PrimitiveType primitive;
             if (decl.Type.IsPrimitiveType(out primitive))
             {
-                Context.Return.Write($"(::{typedef.Declaration.QualifiedOriginalName})");
+                Context.Return.Write($"(typedef ::{typedef.Declaration.QualifiedOriginalName})");
             }
 
             return decl.Type.Visit(this);
@@ -588,7 +588,7 @@ namespace CppSharp.Generators.Cpp
                 && method.Conversion == MethodConversionKind.FunctionToInstanceMethod
                 && Context.ParameterIndex == 0)
             {
-                Context.Return.Write($"(::{@class.QualifiedOriginalName}*)");
+                Context.Return.Write($"({(@class.IsUnion ? "union" : "struct")} ::{@class.QualifiedOriginalName}*)");
                 Context.Return.Write(Helpers.InstanceIdentifier);
                 return;
             }
@@ -596,7 +596,7 @@ namespace CppSharp.Generators.Cpp
             var paramType = Context.Parameter.Type.Desugar();
             var isPointer = paramType.SkipPointerRefs().IsPointer();
             var deref = isPointer ? "->" : ".";
-            var instance = $"(::{@class.QualifiedOriginalName}*)" +
+            var instance = $"({(@class.IsUnion ? "union" : "struct")} ::{@class.QualifiedOriginalName}*)" +
                 $"{Context.Parameter.Name}{deref}{Helpers.InstanceIdentifier}";
 
             if (isPointer)
@@ -654,7 +654,7 @@ namespace CppSharp.Generators.Cpp
 
         public override bool VisitEnumDecl(Enumeration @enum)
         {
-            Context.Return.Write("(::{0}){1}", @enum.QualifiedOriginalName,
+            Context.Return.Write("(enum ::{0}){1}", @enum.QualifiedOriginalName,
                          Context.Parameter.Name);
             return true;
         }

src/Generator/Generators/C/CppSources.cs

@@ -294,7 +294,7 @@ namespace CppSharp.Generators.Cpp
         {
             Write($"{QualifiedIdentifier(@class)}::{@class.Name}(");
 
-            var nativeType = $"::{@class.QualifiedOriginalName}*";
+            var nativeType = $"{(@class.IsUnion ? "union" : "struct")} ::{@class.QualifiedOriginalName}*";
             //WriteLine($"{nativeType} {ClassCtorInstanceParamIdentifier})");
             WriteLine(!withOwnNativeInstanceParam ? $"{nativeType} {ClassCtorInstanceParamIdentifier})" :
                 $"{nativeType} {ClassCtorInstanceParamIdentifier}, bool ownNativeInstance)");
@@ -413,7 +413,8 @@ namespace CppSharp.Generators.Cpp
                         PushBlock(BlockKind.ConstructorBody, @class);
 
                         var @params = GenerateFunctionParamsMarshal(method.Parameters, method);
-                        Write($"{Helpers.InstanceIdentifier} = new ::{method.Namespace.QualifiedOriginalName}(");
+                        Write($@"{Helpers.InstanceIdentifier} = new {(@class.IsUnion ? "union" : "struct")} ::{
+                            method.Namespace.QualifiedOriginalName}(");
                         GenerateFunctionParams(@params);
                         WriteLine(");");
 
@@ -492,7 +493,7 @@ namespace CppSharp.Generators.Cpp
             var field = property?.Field;
             if (field != null)
             {
-                Write($"((::{@class.QualifiedOriginalName}*){Helpers.InstanceIdentifier})->");
+                Write($"(({(@class.IsUnion ? "union" : "struct")} ::{@class.QualifiedOriginalName}*){Helpers.InstanceIdentifier})->");
                 Write($"{field.OriginalName}");
 
                 var isGetter = property.GetMethod == method;
@@ -510,7 +511,7 @@ namespace CppSharp.Generators.Cpp
                 else
                 {
                     if (IsNativeMethod(function))
-                        Write($"((::{@class.QualifiedOriginalName}*){Helpers.InstanceIdentifier})->");
+                        Write($"(({(@class.IsUnion ? "union" : "struct")} ::{@class.QualifiedOriginalName}*){Helpers.InstanceIdentifier})->");
 
                     Write($"{base.GetMethodIdentifier(function, TypePrinterContextKind.Native)}(");
                 }

src/Generator/Generators/CLI/CLIHeaders.cs

@@ -262,10 +262,10 @@ namespace CppSharp.Generators.CLI
             GenerateDeclContext(@class);
             Unindent();
 
-            var nativeType = string.Format("::{0}*", @class.QualifiedOriginalName);
+            string nativeType = $"{(@class.IsUnion ? "union" : "struct")} ::{@class.QualifiedOriginalName}*";
 
             if (CLIGenerator.ShouldGenerateClassNativeField(@class))
-                GenerateClassNativeField(@class, nativeType);
+                GenerateClassNativeField(nativeType);
 
             GenerateClassConstructors(@class, nativeType);
 
@@ -303,15 +303,15 @@ namespace CppSharp.Generators.CLI
             WriteLine("};");
         }
 
-        public void GenerateClassNativeField(Class @class, string nativeType)
+        public void GenerateClassNativeField(string nativeType)
         {
             WriteLineIndent("property {0} NativePtr;", nativeType);
 
             Indent();
-            WriteLine("property System::IntPtr {0}", Helpers.InstanceIdentifier);
+            WriteLine("property ::System::IntPtr {0}", Helpers.InstanceIdentifier);
             WriteOpenBraceAndIndent();
-            WriteLine("virtual System::IntPtr get();");
-            WriteLine("virtual void set(System::IntPtr instance);");
+            WriteLine("virtual ::System::IntPtr get();");
+            WriteLine("virtual void set(::System::IntPtr instance);");
             UnindentAndWriteCloseBrace();
             NewLine();
 
@@ -455,7 +455,7 @@ namespace CppSharp.Generators.CLI
 
             GenerateDeclarationCommon(field);
             if (@class.IsUnion)
-                WriteLine("[System::Runtime::InteropServices::FieldOffset({0})]",
+                WriteLine("[::System::Runtime::InteropServices::FieldOffset({0})]",
                     @class.Layout.Fields.Single(f => f.FieldPtr == field.OriginalPtr).Offset);
             WriteLine("{0} {1};", field.Type, field.Name);
 
@@ -575,8 +575,8 @@ namespace CppSharp.Generators.CLI
         public override void GenerateClassSpecifier(Class @class)
         {
             if (@class.IsUnion)
-                WriteLine("[System::Runtime::InteropServices::StructLayout({0})]",
-                          "System::Runtime::InteropServices::LayoutKind::Explicit");
+                WriteLine("[::System::Runtime::InteropServices::StructLayout({0})]",
+                          "::System::Runtime::InteropServices::LayoutKind::Explicit");
 
             // Nested types cannot have visibility modifiers in C++/CLI.
             var isTopLevel = @class.Namespace is TranslationUnit ||
@@ -760,8 +760,8 @@ namespace CppSharp.Generators.CLI
                     : ((FunctionType)attributedType).CallingConvention;
                 var interopCallConv = callingConvention.ToInteropCallConv();
                 if (interopCallConv != System.Runtime.InteropServices.CallingConvention.Winapi)
-                    WriteLine("[System::Runtime::InteropServices::UnmanagedFunctionPointer" + 
-                        "(System::Runtime::InteropServices::CallingConvention::{0})] ",
+                    WriteLine("[::System::Runtime::InteropServices::UnmanagedFunctionPointer" + 
+                        "(::System::Runtime::InteropServices::CallingConvention::{0})] ",
                         interopCallConv);
 
                 var visibility = !insideClass ? "public " : string.Empty;

src/Generator/Generators/CLI/CLIMarshal.cs

@@ -83,9 +83,9 @@ namespace CppSharp.Generators.CLI
             var delegateType = function.ToString();
 
             Context.Return.Write("safe_cast<{0}>(", delegateType + "^");
-            Context.Return.Write("System::Runtime::InteropServices::Marshal::");
+            Context.Return.Write("::System::Runtime::InteropServices::Marshal::");
             Context.Return.Write("GetDelegateForFunctionPointer(");
-            Context.Return.Write("System::IntPtr({0}), {1}::typeid))", Context.ReturnVarName,
+            Context.Return.Write("::System::IntPtr({0}), {1}::typeid))", Context.ReturnVarName,
                 delegateType.TrimEnd('^'));
 
             return true;
@@ -223,9 +223,9 @@ namespace CppSharp.Generators.CLI
             if (decl.Type.IsPointerTo(out function))
             {
                 Context.Return.Write($"{Context.ReturnVarName} == nullptr ? nullptr : safe_cast<{typedef}>(");
-                Context.Return.Write("System::Runtime::InteropServices::Marshal::");
+                Context.Return.Write("::System::Runtime::InteropServices::Marshal::");
                 Context.Return.Write("GetDelegateForFunctionPointer(");
-                Context.Return.Write("IntPtr({0}), {1}::typeid))",Context.ReturnVarName,
+                Context.Return.Write("::System::IntPtr({0}), {1}::typeid))", Context.ReturnVarName,
                     typedef.ToString().TrimEnd('^'));
                 return true;
             }
@@ -280,8 +280,7 @@ namespace CppSharp.Generators.CLI
             if (@class.IsRefType && needsCopy)
             {
                 var name = Generator.GeneratedIdentifier(Context.ReturnVarName);
-                Context.Before.WriteLine("auto {0} = new ::{1}({2});", name,
-                    @class.QualifiedOriginalName, Context.ReturnVarName);
+                Context.Before.WriteLine($"auto {name} = new {(@class.IsUnion ? "union" : "struct")} ::{@class.QualifiedOriginalName}({Context.ReturnVarName});");
                 instance = name;
 
                 ownNativeInstance = true;
@@ -306,7 +305,7 @@ namespace CppSharp.Generators.CLI
                     instance);
 
             Context.Return.Write("::{0}(", QualifiedIdentifier(@class));
-            Context.Return.Write("(::{0}*)", @class.QualifiedOriginalName);
+            Context.Return.Write($"({(@class.IsUnion ? "union" : "struct")} ::{@class.QualifiedOriginalName}*)");
             Context.Return.Write("{0}{1})", instance, ownNativeInstance ? ", true" : "");
         }
 
@@ -449,7 +448,7 @@ namespace CppSharp.Generators.CLI
 
                     supportBefore.WriteLine($"if ({Context.Parameter.Name}->Length != {array.Size})");
                     supportBefore.WriteOpenBraceAndIndent();
-                    supportBefore.WriteLine($"throw gcnew System::InvalidOperationException(\"Source array size must equal destination array size.\");");
+                    supportBefore.WriteLine($"throw gcnew ::System::InvalidOperationException(\"Source array size must equal destination array size.\");");
                     supportBefore.UnindentAndWriteCloseBrace();
 
                     string nativeVal = string.Empty;
@@ -494,7 +493,7 @@ namespace CppSharp.Generators.CLI
 
             var sb = new StringBuilder();
             sb.AppendFormat("static_cast<{0}>(", type);
-            sb.Append("System::Runtime::InteropServices::Marshal::");
+            sb.Append("::System::Runtime::InteropServices::Marshal::");
             sb.Append("GetFunctionPointerForDelegate(");
             sb.AppendFormat("{0}).ToPointer())", Context.Parameter.Name);
             Context.Return.Write(sb.ToString());
@@ -529,7 +528,7 @@ namespace CppSharp.Generators.CLI
                     ArgumentPrefix.Write("&");
                 }
 
-                Context.Return.Write("(::{0}){1}{2}", @enum.QualifiedOriginalName,
+                Context.Return.Write("(enum ::{0}){1}{2}", @enum.QualifiedOriginalName,
                     isRef ? string.Empty : "*", Context.Parameter.Name);
                 return true;
             }
@@ -728,12 +727,12 @@ namespace CppSharp.Generators.CLI
                 && method.Conversion == MethodConversionKind.FunctionToInstanceMethod
                 && Context.ParameterIndex == 0)
             {
-                Context.Return.Write("(::{0}*)", @class.QualifiedOriginalName);
+                Context.Return.Write($"({(@class.IsUnion ? "union" : "struct")} ::{@class.QualifiedOriginalName}*)");
                 Context.Return.Write("NativePtr");
                 return;
             }
 
-            Context.Return.Write("(::{0}*)", @class.QualifiedOriginalName);
+            Context.Return.Write($"({(@class.IsUnion ? "union" : "struct")} ::{@class.QualifiedOriginalName}*)");
             Context.Return.Write("{0}->NativePtr", Context.Parameter.Name);
         }
 
@@ -858,7 +857,7 @@ namespace CppSharp.Generators.CLI
 
         public override bool VisitEnumDecl(Enumeration @enum)
         {
-            Context.Return.Write("(::{0}){1}", @enum.QualifiedOriginalName,
+            Context.Return.Write("(enum ::{0}){1}", @enum.QualifiedOriginalName,
                          Context.Parameter.Name);
             return true;
         }

src/Generator/Generators/CLI/CLISources.cs

@@ -136,18 +136,18 @@ namespace CppSharp.Generators.CLI
                 var qualifiedIdentifier = QualifiedIdentifier(@class);
 
                 PushBlock(BlockKind.Method);
-                WriteLine("System::IntPtr {0}::{1}::get()",
+                WriteLine("::System::IntPtr {0}::{1}::get()",
                     qualifiedIdentifier, Helpers.InstanceIdentifier);
                 WriteOpenBraceAndIndent();
-                WriteLine("return System::IntPtr(NativePtr);");
+                WriteLine("return ::System::IntPtr(NativePtr);");
                 UnindentAndWriteCloseBrace();
                 PopBlock(NewLineKind.BeforeNextBlock);
 
                 PushBlock(BlockKind.Method);
-                WriteLine("void {0}::{1}::set(System::IntPtr object)",
+                WriteLine("void {0}::{1}::set(::System::IntPtr object)",
                     qualifiedIdentifier, Helpers.InstanceIdentifier);
                 WriteOpenBraceAndIndent();
-                var nativeType = $"::{@class.QualifiedOriginalName}*";
+                var nativeType = $"{(@class.IsUnion ? "union" : "struct")} ::{@class.QualifiedOriginalName}*";
                 WriteLine("NativePtr = ({0})object.ToPointer();", nativeType);
                 UnindentAndWriteCloseBrace();
                 PopBlock(NewLineKind.BeforeNextBlock);
@@ -260,7 +260,7 @@ namespace CppSharp.Generators.CLI
                 WriteOpenBraceAndIndent();
                 WriteLine("auto __nativePtr = NativePtr;");
                 WriteLine("NativePtr = 0;");
-                WriteLine("delete (::{0}*) __nativePtr;", @class.QualifiedOriginalName);
+                WriteLine($"delete ({(@class.IsUnion ? "union" : "struct")} ::{@class.QualifiedOriginalName}*) __nativePtr;", @class.QualifiedOriginalName);
                 UnindentAndWriteCloseBrace();
             }
 
@@ -398,7 +398,7 @@ namespace CppSharp.Generators.CLI
                 if (decl is Variable)
                     variable = $"::{@class.QualifiedOriginalName}::{decl.OriginalName}";
                 else
-                    variable = $"((::{@class.QualifiedOriginalName}*)NativePtr)->{decl.OriginalName}";
+                    variable = $"(({(@class.IsUnion ? "union" : "struct")} ::{@class.QualifiedOriginalName}*)NativePtr)->{decl.OriginalName}";
 
                 var ctx = new MarshalContext(Context, CurrentIndentation)
                 {
@@ -483,8 +483,10 @@ namespace CppSharp.Generators.CLI
                 string variable;
                 if (decl is Variable)
                     variable = $"::{@class.QualifiedOriginalName}::{decl.OriginalName}";
+                else if (CLIGenerator.ShouldGenerateClassNativeField(@class))
+                    variable = $"NativePtr->{decl.OriginalName}";
                 else
-                    variable = $"((::{@class.QualifiedOriginalName}*)NativePtr)->{decl.OriginalName}";
+                    variable = $"(({(@class.IsUnion ? "union" : "struct")} ::{@class.QualifiedOriginalName}*)NativePtr)->{decl.OriginalName}";
 
                 var ctx = new MarshalContext(Context, CurrentIndentation)
                 {
@@ -543,12 +545,11 @@ namespace CppSharp.Generators.CLI
             WriteLine("auto _fptr = (void (*)({0}))Marshal::GetFunctionPointerForDelegate({1}Instance).ToPointer();",
                 args, delegateName);
 
-            WriteLine("((::{0}*)NativePtr)->{1}.Connect(_fptr);", @class.QualifiedOriginalName,
-                @event.OriginalName);
+            WriteLine($"(({(@class.IsUnion ? "union" : "struct")} ::{@class.QualifiedOriginalName}*)NativePtr)->{@event.OriginalName}.Connect(_fptr);");
 
             UnindentAndWriteCloseBrace();
 
-            WriteLine("_{0} = static_cast<{1}>(System::Delegate::Combine(_{0}, evt));",
+            WriteLine("_{0} = static_cast<{1}>(::System::Delegate::Combine(_{0}, evt));",
                 @event.Name, @event.Type);
 
             UnindentAndWriteCloseBrace();
@@ -560,7 +561,7 @@ namespace CppSharp.Generators.CLI
                       @event.Name, @event.Type);
             WriteOpenBraceAndIndent();
 
-            WriteLine("_{0} = static_cast<{1}>(System::Delegate::Remove(_{0}, evt));",
+            WriteLine("_{0} = static_cast<{1}>(::System::Delegate::Remove(_{0}, evt));",
                 @event.Name, @event.Type);
 
             UnindentAndWriteCloseBrace();
@@ -630,7 +631,7 @@ namespace CppSharp.Generators.CLI
 
             Write("{0}::{1}(", qualifiedIdentifier, @class.Name);
 
-            var nativeType = string.Format("::{0}*", @class.QualifiedOriginalName);
+            string nativeType = $"{(@class.IsUnion ? "union" : "struct")} ::{@class.QualifiedOriginalName}*";
             WriteLine(!withOwnNativeInstanceParam ? "{0} native)" : "{0} native, bool ownNativeInstance)", nativeType);
 
             var hasBase = GenerateClassConstructorBase(@class, null, withOwnNativeInstanceParam);
@@ -784,7 +785,8 @@ namespace CppSharp.Generators.CLI
                     if (!@class.IsAbstract)
                     {
                         var @params = GenerateFunctionParamsMarshal(method.Parameters, method);
-                        Write("NativePtr = new ::{0}(", method.Namespace.QualifiedOriginalName);
+                        Write($@"NativePtr = new {(@class.IsUnion ? "union" : "struct")} ::{
+                            @class.QualifiedOriginalName}(");
                         GenerateFunctionParams(@params);
                         WriteLine(");");
                     }
@@ -867,8 +869,8 @@ namespace CppSharp.Generators.CLI
                 names.Add(marshal.Context.Return);
             }
 
-            WriteLine("::{0} _native({1});", @class.QualifiedOriginalName,
-                      string.Join(", ", names));
+            WriteLine($@"{(@class.IsUnion ? "union" : "struct")} ::{
+                @class.QualifiedOriginalName} _native({string.Join(", ", names)});");
 
             GenerateValueTypeConstructorCallProperties(@class);
         }
@@ -959,7 +961,7 @@ namespace CppSharp.Generators.CLI
             var isValueType = @class != null && @class.IsValueType;
             if (isValueType && !IsNativeFunctionOrStaticMethod(function))
             {
-                WriteLine("auto {0} = ::{1}();", valueMarshalName, @class.QualifiedOriginalName);
+                WriteLine($"auto {valueMarshalName} = {(@class.IsUnion ? "union" : "struct")} ::{@class.QualifiedOriginalName}();");
 
                 var param = new Parameter { Name = "(*this)" , Namespace = function.Namespace };
                 var ctx = new MarshalContext(Context, CurrentIndentation)
@@ -1018,7 +1020,7 @@ namespace CppSharp.Generators.CLI
                     if (isValueType)
                         Write($"{valueMarshalName}.");
                     else if (IsNativeMethod(function))
-                        Write("((::{0}*)NativePtr)->", @class.QualifiedOriginalName);
+                        Write($"(({(@class.IsUnion ? "union" : "struct")} ::{@class.QualifiedOriginalName}*)NativePtr)->");
                     Write("{0}(", function.OriginalName);
                 }
 
@@ -1067,7 +1069,7 @@ namespace CppSharp.Generators.CLI
                 {
                     WriteLine("if ({0} == nullptr) return {1};",
                         returnIdentifier,
-                        isIntPtr ? "System::IntPtr()" : "nullptr");
+                        isIntPtr ? "::System::IntPtr()" : "nullptr");
                 }
 
                 var ctx = new MarshalContext(Context, CurrentIndentation)
@@ -1103,10 +1105,10 @@ namespace CppSharp.Generators.CLI
                 foreach (var param in method.Parameters.Where(
                     p => p.Type.IsPrimitiveType(PrimitiveType.Char)))
                 {
-                    WriteLine("if ({0} < System::Char::MinValue || {0} > System::SByte::MaxValue)", param.Name);
+                    WriteLine("if ({0} < ::System::Char::MinValue || {0} > ::System::SByte::MaxValue)", param.Name);
                     // C++/CLI can actually handle char -> sbyte in all case, this is for compatibility with the C# generator
                     WriteLineIndent(
-                        "throw gcnew System::OverflowException(\"{0} must be in the range {1} - {2}.\");",
+                        "throw gcnew ::System::OverflowException(\"{0} must be in the range {1} - {2}.\");",
                         param.Name, (int) char.MinValue, sbyte.MaxValue);
                 }
             }

src/Generator/Generators/CLI/CLITypePrinter.cs

@@ -38,7 +38,7 @@ namespace CppSharp.Generators.CLI
             if (array.SizeType == ArrayType.ArraySize.Incomplete &&
                 array.Type.Desugar().IsPrimitiveType(PrimitiveType.Char) &&
                 array.QualifiedType.Qualifiers.IsConst)
-                return "System::String^";
+                return VisitCILType(new CILType(typeof(string)), quals);
 
             return $"cli::array<{array.Type.Visit(this)}>^";
         }
@@ -75,9 +75,9 @@ namespace CppSharp.Generators.CLI
 
             var str = string.Empty;
             if(param.Usage == ParameterUsage.Out)
-                str += "[System::Runtime::InteropServices::Out] ";
+                str += "[::System::Runtime::InteropServices::Out] ";
             else if (param.Usage == ParameterUsage.InOut)
-                str += "[System::Runtime::InteropServices::In, System::Runtime::InteropServices::Out] ";
+                str += "[::System::Runtime::InteropServices::In, ::System::Runtime::InteropServices::Out] ";
 
             str += type;
 
@@ -179,8 +179,8 @@ namespace CppSharp.Generators.CLI
                 case PrimitiveType.Void: return "void";
                 case PrimitiveType.Char16:
                 case PrimitiveType.Char32:
-                case PrimitiveType.WideChar: return "System::Char";
-                case PrimitiveType.Char: return Options.MarshalCharAsManagedChar ? "System::Char" : "char";
+                case PrimitiveType.WideChar: return "::System::Char";
+                case PrimitiveType.Char: return Options.MarshalCharAsManagedChar ? "::System::Char" : "char";
                 case PrimitiveType.SChar: return "signed char";
                 case PrimitiveType.UChar: return "unsigned char";
                 case PrimitiveType.Short: return "short";
@@ -200,7 +200,7 @@ namespace CppSharp.Generators.CLI
                 case PrimitiveType.IntPtr: return "IntPtr";
                 case PrimitiveType.UIntPtr: return "UIntPtr";
                 case PrimitiveType.Null: return "void*";
-                case PrimitiveType.String: return "System::String";
+                case PrimitiveType.String: return "::System::String";
             }
 
             throw new NotSupportedException();
@@ -300,7 +300,7 @@ namespace CppSharp.Generators.CLI
             if (!type.Type.IsValueType)
                 result += "^";
 
-            return result;
+            return $"::{result}";
         }
 
         public override TypePrinterResult VisitUnsupportedType(UnsupportedType type, TypeQualifiers quals)

src/Generator/Generators/CSharp/CSharpSources.cs

@@ -375,7 +375,7 @@ namespace CppSharp.Generators.CSharp
             base.GenerateDeclarationCommon(decl);
 
             foreach (Attribute attribute in decl.Attributes)
-                WriteLine("[{0}({1})]", attribute.Type.FullName, attribute.Value);
+                WriteLine("[global::{0}({1})]", attribute.Type.FullName, attribute.Value);
         }
 
         #region Classes
@@ -2365,7 +2365,7 @@ internal static{(@new ? " new" : string.Empty)} {printedClass} __GetOrCreateInst
 internal static{(@new ? " new" : string.Empty)} {printedClass} __GetInstance({TypePrinter.IntPtrType} native)
 {{
     if (!NativeToManagedMap.TryGetValue(native, out var managed))
-        throw new System.Exception(""No managed instance was found"");
+        throw new global::System.Exception(""No managed instance was found"");
     var result = ({printedClass})managed;
     if (result.{Helpers.OwnsNativeInstanceIdentifier})
         result.SetupVTables();
@@ -3423,6 +3423,11 @@ internal static{(@new ? " new" : string.Empty)} {printedClass} __GetInstance({Ty
             if (function.IsPure)
                 return;
 
+            if (function.OriginalName == "system_do_it")
+            {
+                System.Diagnostics.Debugger.Break();
+            }
+
             PushBlock(BlockKind.InternalsClassMethod);
             var callConv = function.CallingConvention.ToInteropCallConv();
 
@@ -3555,7 +3560,7 @@ internal static{(@new ? " new" : string.Empty)} {printedClass} __GetInstance({Ty
             {
                 WriteLine($"var path = \"{path}\";");
                 WriteLine("var image = CppSharp.SymbolResolver.LoadImage(ref path);");
-                WriteLine("if (image == IntPtr.Zero) throw new System.DllNotFoundException(path);");
+                WriteLine("if (image == IntPtr.Zero) throw new global::System.DllNotFoundException(path);");
 
                 foreach (var symbol in symbols)
                 {

src/Generator/Types/Std/Stdlib.CLI.cs

@@ -148,7 +148,7 @@ namespace CppSharp.Types.Std
         public override Type CLISignatureType(TypePrinterContext ctx)
         {
             return new CustomType(
-                $"System::Collections::Generic::List<{ctx.GetTemplateParameterList()}>^");
+                $"::System::Collections::Generic::List<{ctx.GetTemplateParameterList()}>^");
         }
 
         public override void CLIMarshalToNative(MarshalContext ctx)
@@ -221,7 +221,7 @@ namespace CppSharp.Types.Std
             var tmpVarName = "_tmp" + ctx.ArgName;
             
             ctx.Before.WriteLine(
-                "auto {0} = gcnew System::Collections::Generic::List<{1}>();",
+                "auto {0} = gcnew ::System::Collections::Generic::List<{1}>();",
                 tmpVarName, managedType);
 
             string retVarName = ctx.ReturnType.Type.Desugar().IsPointer() ? $"*{ctx.ReturnVarName}" : ctx.ReturnVarName;
@@ -266,7 +266,7 @@ namespace CppSharp.Types.Std
         {
             var type = Type as TemplateSpecializationType;
             return new CustomType(
-                $@"System::Collections::Generic::Dictionary<{
+                $@"::System::Collections::Generic::Dictionary<{
                     type.Arguments[0].Type}, {type.Arguments[1].Type}>^");
         }
 

tests/CSharp/CSharp.Gen.cs

@@ -227,7 +227,7 @@ namespace CppSharp.Tests
             }
 
             return new CustomType(
-                $@"System.Collections.Generic.{
+                $@"global::System.Collections.Generic.{
                     (ctx.MarshalKind == MarshalKind.DefaultExpression ? "List" : "IList")}<{
                     ctx.GetTemplateParameterList()}>");
         }

tests/Common/Common.Tests.cs

@@ -1114,4 +1114,25 @@ This is a very long string. This is a very long string. This is a very long stri
         Common.PointerToPrimitiveTypedefPointerTestMethod(ref a, 100);
         Assert.AreEqual(100, a);
     }
+
+    [Test]
+    public void TestConflictName()
+    {
+        using (var system = new CommonTest.System())
+        {
+            Common.TakeConflictName(system);
+            Assert.That(system.Field1, Is.EqualTo(5));
+            Assert.That(system.Field2, Is.EqualTo(10));
+        }
+    }
+
+    [Test, Ignore("This was exposed by another bug and doesn't work yet.")]
+    public void TestFreeFunctionReturnByValue()
+    {
+        using (var system = Common.FreeFunctionReturnByValue)
+        {
+            Assert.That(system.Field1, Is.EqualTo(5));
+            Assert.That(system.Field2, Is.EqualTo(10));
+        }
+    }
 }

tests/Common/Common.cpp

@@ -1460,3 +1460,20 @@ bool ClassWithOverloadedOperators::operator<(const ClassWithOverloadedOperators&
 }
 
 int TestIndexedPropertiesInValueType::operator[](int i) { return i; }
+
+extern "C"
+{
+    void takeConflictName(struct system* self)
+    {
+        self->field1 = 5;
+        self->field2 = 10;
+    }
+
+    struct system freeFunctionReturnByValue()
+    {
+        struct system s;
+        s.field1 = 5;
+        s.field2 = 10;
+        return s;
+    }
+} // extern "C"

tests/Common/Common.h

@@ -1549,3 +1549,16 @@ void DLL_API PointerToTypedefPointerTestMethod(LPPointerToTypedefPointerTest* lp
 typedef int *LPINT;
 
 void DLL_API PointerToPrimitiveTypedefPointerTestMethod(LPINT lp, int valToSet);
+
+// this name must match a universally accessible system function or class to reproduce the bug
+struct system
+{
+    int32_t field1;
+    int32_t field2;
+};
+
+extern "C"
+{
+    DLL_API void takeConflictName(struct system* self);
+    DLL_API struct system freeFunctionReturnByValue();
+} // extern "C"