Project experimental attribute

src/Tests/TestComponentCSharp/CustomExperimentClass.cpp

@@ -0,0 +1,17 @@
+#include "pch.h"
+#include "CustomExperimentClass.h"
+#include "CustomExperimentClass.g.cpp"
+
+namespace winrt::TestComponentCSharp::implementation
+{
+    int32_t CustomExperimentClass::Value()
+    {
+        return 4;
+    }
+    void CustomExperimentClass::Value(int32_t value)
+    {
+    }
+    void CustomExperimentClass::f()
+    {
+    }
+}

src/Tests/TestComponentCSharp/CustomExperimentClass.h

@@ -0,0 +1,20 @@
+#pragma once
+#include "CustomExperimentClass.g.h"
+
+namespace winrt::TestComponentCSharp::implementation
+{
+    struct CustomExperimentClass : CustomExperimentClassT<CustomExperimentClass>
+    {
+        CustomExperimentClass() = default;
+
+        int32_t Value();
+        void Value(int32_t value);
+        void f();
+    };
+}
+namespace winrt::TestComponentCSharp::factory_implementation
+{
+    struct CustomExperimentClass : CustomExperimentClassT<CustomExperimentClass, implementation::CustomExperimentClass>
+    {
+    };
+}

src/Tests/TestComponentCSharp/TestComponentCSharp.idl

@@ -590,6 +590,15 @@ And this is another one"
         Boolean Equals(UnSealedCustomEquals other);
     }
 
+    [default_interface]
+    [experimental]
+    runtimeclass CustomExperimentClass
+    {
+        CustomExperimentClass();
+        Int32 Value{ get; set; };
+        void f();
+    }
+
     // Compile time test for sub windows namespace
     namespace Windows
     {

src/Tests/TestComponentCSharp/TestComponentCSharp.vcxproj

@@ -80,6 +80,7 @@
   <ItemGroup>
     <ClInclude Include="ABCDEFGHIJKLMNOPQRSTUVQXYZabcdefghijklmnopqrstuvqxyzABCDEFGHIJKLMNOPQRSTUVQXYZabcdefghijklmnopqrstuvqxyzABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz.h" />
     <ClInclude Include="AnotherAssembly.SetPropertyClass.h" />
+    <ClInclude Include="CustomExperimentClass.h" />
     <ClInclude Include="CustomEquals.h" />
     <ClInclude Include="ManualProjectionTestClasses.h" />
     <ClInclude Include="pch.h" />
@@ -97,6 +98,7 @@
     <ClCompile Include="$(GeneratedFilesDir)module.g.cpp" />
     <ClCompile Include="ABCDEFGHIJKLMNOPQRSTUVQXYZabcdefghijklmnopqrstuvqxyzABCDEFGHIJKLMNOPQRSTUVQXYZabcdefghijklmnopqrstuvqxyzABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz.cpp" />
     <ClCompile Include="AnotherAssembly.SetPropertyClass.cpp" />
+    <ClCompile Include="CustomExperimentClass.cpp" />
     <ClCompile Include="CustomEquals.cpp" />
     <ClCompile Include="pch.cpp">
       <PrecompiledHeader>Create</PrecompiledHeader>

src/Tests/TestComponentCSharp/TestComponentCSharp.vcxproj.filters

@@ -20,6 +20,7 @@
     <ClCompile Include="ABCDEFGHIJKLMNOPQRSTUVQXYZabcdefghijklmnopqrstuvqxyzABCDEFGHIJKLMNOPQRSTUVQXYZabcdefghijklmnopqrstuvqxyzABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz.cpp" />
     <ClCompile Include="AnotherAssembly.SetPropertyClass.cpp" />
     <ClCompile Include="CustomEquals.cpp" />
+    <ClCompile Include="CustomExperimentClass.cpp" />
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="pch.h" />
@@ -33,6 +34,7 @@
     <ClInclude Include="ABCDEFGHIJKLMNOPQRSTUVQXYZabcdefghijklmnopqrstuvqxyzABCDEFGHIJKLMNOPQRSTUVQXYZabcdefghijklmnopqrstuvqxyzABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz.h" />
     <ClInclude Include="AnotherAssembly.SetPropertyClass.h" />
     <ClInclude Include="CustomEquals.h" />
+    <ClInclude Include="CustomExperimentClass.h" />
   </ItemGroup>
   <ItemGroup>
     <Midl Include="TestComponentCSharp.idl" />

src/Tests/UnitTest/TestComponentCSharp_Tests.cs

@@ -2905,5 +2905,12 @@ public void TestObjectFunctions()
             Assert.True(eighth.Equals(seventh));
             Assert.False(seventh.Equals(eighth));
         }
+
+        // Manually verify warning for experimental.
+        private void TestExperimentAttribute()
+        {
+            CustomExperimentClass custom = new CustomExperimentClass();
+            custom.f();
+        }
     }
 }

src/cswinrt/code_writers.h

@@ -1697,7 +1697,8 @@ remove => %;
                     allow_multiple = true;
                 }
                 if (attribute_name != "DefaultOverload" && attribute_name != "Overload" && 
-                    attribute_name != "AttributeUsage" && attribute_name != "ContractVersion")
+                    attribute_name != "AttributeUsage" && attribute_name != "ContractVersion" &&
+                    attribute_name != "Experimental")
                 {
                     continue;
                 }