Generate valid C# for templates with external specializations only

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

src/AST/ClassExtensions.cs

@@ -247,25 +247,17 @@ namespace CppSharp.AST
             return null;
         }
 
-        public static bool HasDependentValueFieldInLayout(this Class @class)
-        {
-            if (@class.Fields.Any(f => IsValueDependent(f.Type)))
-                return true;
-
-            if (@class.Bases.Where(b => b.IsClass).Select(
-                b => b.Class).Any(HasDependentValueFieldInLayout))
-                return true;
-
+        public static bool HasDependentValueFieldInLayout(this Class @class,
+            IEnumerable<ClassTemplateSpecialization> specializations = null) =>
+            @class.Fields.Any(f => IsValueDependent(f.Type)) ||
+            @class.Bases.Where(b => b.IsClass).Select(
+                b => b.Class).Any(c => c.HasDependentValueFieldInLayout()) ||
             // HACK: Clang can't always resolve complex templates such as the base of std::atomic in msvc
-            if (@class.IsTemplate && @class.Specializations.Any(
-                s => s.Layout.Fields.Any(
-                    f => f.QualifiedType.Type.TryGetDeclaration(
-                        out ClassTemplateSpecialization specialization) &&
-                        specialization.TemplatedDecl.TemplatedClass.HasDependentValueFieldInLayout())))
-                return true;
-
-            return false;
-        }
+            (@class.IsTemplate && (specializations ?? @class.Specializations).Any(
+            s => s.Layout.Fields.Any(
+                f => f.QualifiedType.Type.TryGetDeclaration(
+                    out ClassTemplateSpecialization specialization) &&
+                    specialization.TemplatedDecl.TemplatedClass.HasDependentValueFieldInLayout())));
 
         public static IEnumerable<Property> GetConstCharFieldProperties(this Class @class) =>
             @class.Properties.Where(p => p.HasGetter && p.HasSetter &&

src/CppParser/Parser.cpp

@@ -3067,7 +3067,9 @@ void Parser::CompleteIfSpecializationType(const clang::QualType& QualType)
     Scope Scope(nullptr, Scope::ScopeFlags::ClassScope, c->getSema().getDiagnostics());
     c->getSema().TUScope = &Scope;
 
-    InstantiateSpecialization(CTS);
+    if (!CTS->isCompleteDefinition())
+        c->getSema().InstantiateClassTemplateSpecialization(CTS->getBeginLoc(),
+            CTS, clang::TemplateSpecializationKind::TSK_ImplicitInstantiation, false);
 
     c->getSema().getDiagnostics().setClient(existingClient, false);
     c->getSema().TUScope = nullptr;
@@ -3083,32 +3085,6 @@ void Parser::CompleteIfSpecializationType(const clang::QualType& QualType)
     }
 }
 
-void Parser::InstantiateSpecialization(clang::ClassTemplateSpecializationDecl* CTS)
-{
-    using namespace clang;
-
-    if (!CTS->isCompleteDefinition())
-    {
-        c->getSema().InstantiateClassTemplateSpecialization(CTS->getBeginLoc(),
-            CTS, clang::TemplateSpecializationKind::TSK_ImplicitInstantiation, false);
-    }
-
-    for (auto Decl : CTS->decls())
-    {
-        if (Decl->getKind() == Decl::Kind::CXXRecord)
-        {
-            CXXRecordDecl* Nested = cast<CXXRecordDecl>(Decl);
-            CXXRecordDecl* Template = Nested->getInstantiatedFromMemberClass();
-            if (Template && !Nested->isCompleteDefinition() && !Nested->hasDefinition())
-            {
-                c->getSema().InstantiateClass(Nested->getBeginLoc(), Nested, Template,
-                    MultiLevelTemplateArgumentList(CTS->getTemplateArgs()),
-                    clang::TemplateSpecializationKind::TSK_ImplicitInstantiation, false);
-            }
-        }
-    }
-}
-
 Parameter* Parser::WalkParameter(const clang::ParmVarDecl* PVD,
     const clang::SourceLocation& ParamStartLoc)
 {

src/CppParser/Parser.h

@@ -137,7 +137,6 @@ private:
     std::string GetTypeName(const clang::Type* Type);
     bool CanCheckCodeGenInfo(const clang::Type* Ty);
     void CompleteIfSpecializationType(const clang::QualType& QualType);
-    void InstantiateSpecialization(clang::ClassTemplateSpecializationDecl* CTS);
     Parameter* WalkParameter(const clang::ParmVarDecl* PVD,
         const clang::SourceLocation& ParamStartLoc);
     void SetBody(const clang::FunctionDecl* FD, Function* F);

src/Generator/Generators/CSharp/CSharpSources.cs

@@ -330,7 +330,7 @@ namespace CppSharp.Generators.CSharp
                 GenerateClassTemplateSpecializationsInternals(
                     nestedTemplate, nestedTemplate.Specializations);
 
-            if (template.HasDependentValueFieldInLayout() ||
+            if (template.HasDependentValueFieldInLayout(specializations) ||
                 template.Specializations.Intersect(specializations).Count() == specializations.Count)
                 foreach (var specialization in generated)
                     GenerateClassInternals(specialization);

tests/NamespacesDerived/NamespacesDerived.h

@@ -2,6 +2,7 @@
 #include "../NamespacesBase/NamespacesBase.h"
 #include "Independent.h"
 #include <string>
+#include <unordered_map>
 #include <vector>
 
 // Namespace clashes with NamespacesBase.OverlappingNamespace
@@ -71,6 +72,7 @@ private:
     IndependentFields<int> independentSpecialization;
     IndependentFields<Derived> independentExternalSpecialization;
     IndependentFields<Derived>::Nested nestedInExternalSpecialization;
+    std::unordered_map<int, Derived> externalSpecializationOnly;
 };
 
 class DLL_API HasVirtualInDependency : public HasVirtualInCore