VS: Do not reference output assemblies if not possible for CSharp target

Since commit v3.9.0-rc4~4^2 (Vs: allow CSharp targets to be linked to
CXX targets, 2017-06-20) CSharp targets get `ProjectReference` entries
to their dependencies.  This causes VS to also reference the
dependency's output assembly by default, which is incorrect for
non-managed targets.

Fix this by setting `ReferenceOutputAssembly` to `false` for targets
that can't provide output assemblies.  Unmanaged C++ targets (shared
libs & executables) can still be referenced and a warning will be shown
in the IDE but the build will not break anymore.

Fixes: #17172

3 files changed, 25 insertions, 0 deletions

diff --git a/Tests/CSharpLinkToCxx/CMakeLists.txt b/Tests/CSharpLinkToCxx/CMakeLists.txt
index c4269e0..153c57c 100644
--- a/Tests/CSharpLinkToCxx/CMakeLists.txt
+++ b/Tests/CSharpLinkToCxx/CMakeLists.txt
@@ -15,3 +15,9 @@ target_compile_options(CLIApp PRIVATE "/clr")
 add_executable(CSharpLinkToCxx csharp.cs)
 
 target_link_libraries(CSharpLinkToCxx CLIApp)
+
+# this unmanaged C++ library will be added to the C#/.NET
+# references of CSharpLinkToCxx but it will show a warning
+# because it is unmanaged
+add_library(CppNativeApp SHARED cpp_native.hpp cpp_native.cpp)
+target_link_libraries(CSharpLinkToCxx CppNativeApp)
diff --git a/Tests/CSharpLinkToCxx/cpp_native.cpp b/Tests/CSharpLinkToCxx/cpp_native.cpp
new file mode 100644
index 0000000..dc7670f
--- /dev/null
+++ b/Tests/CSharpLinkToCxx/cpp_native.cpp
@@ -0,0 +1,10 @@
+#include "cpp_native.hpp"
+
+#include <iostream>
+
+namespace CppApp {
+void MyCpp::testMyCpp()
+{
+  std::cout << "#message from CppApp" << std::endl;
+}
+}
diff --git a/Tests/CSharpLinkToCxx/cpp_native.hpp b/Tests/CSharpLinkToCxx/cpp_native.hpp
new file mode 100644
index 0000000..0fa1a3b
--- /dev/null
+++ b/Tests/CSharpLinkToCxx/cpp_native.hpp
@@ -0,0 +1,9 @@
+#pragma once
+
+namespace CppApp {
+class MyCpp
+{
+public:
+  void testMyCpp();
+};
+}