Fix compiler errors in debug/c++20 (#1892)

Author: duckdoom5

include/CppSharp.h

@@ -207,11 +207,12 @@ namespace clix {
     typename detail::StringTypeSelector<encoding>::Type,
     System::String ^
   >::Type marshalString(SourceType string) {
+      constexpr detail::MarshalingDirection direction =
+          detail::IfManaged<SourceType>::Result ? detail::CxxFromNet : detail::NetFromCxx;
+      using StringMarshaler = detail::StringMarshaler<direction>;
 
-    // Pass on the call to our nifty template routines
-    return detail::StringMarshaler<
-      detail::IfManaged<SourceType>::Result ? detail::CxxFromNet : detail::NetFromCxx
-    >::marshal<encoding, SourceType>(string);
+      // Pass on the call to our nifty template routines
+      return StringMarshaler::template marshal<encoding, SourceType>(string);
 
   }
 

tests/dotnet/CSharp/CSharpTemplates.h

@@ -218,7 +218,8 @@ void Base<T>::Nested::f(const T& t)
 template <typename T>
 void Base<T>::invokeFriend()
 {
-    f(Nested());
+    Nested n;
+    f(n);
 }
 
 template <typename T>

tests/dotnet/NamespacesDerived/NamespacesDerived.h

@@ -101,7 +101,14 @@ template<typename T>
 class CustomAllocator
 {
 public:
-    typedef T value_type;
+    using value_type = T;
+    using pointer_type = void*;
+
+    CustomAllocator() = default;
+
+    template <typename U>
+    CustomAllocator(const CustomAllocator<U>&) noexcept {
+    }
 
     T* allocate(size_t cnt, const void* = 0) { return 0; }
     void deallocate(T* p, size_t cnt) {}