Convert exception help context parsing to managed

src/tests/Interop/COM/NETClients/Primitives/ErrorTests.cs

@@ -19,6 +19,7 @@ public void Run()
         {
             this.VerifyExpectedException();
             this.VerifyReturnHResult();
+            this.VerifyHelpLink();
         }
 
         private void VerifyExpectedException()
@@ -40,21 +41,29 @@ private void VerifyReturnHResult()
 
             var hrs = new[]
             {
-                    unchecked((int)0x80004001),
-                    unchecked((int)0x80004003),
-                    unchecked((int)0x80070005),
-                    unchecked((int)0x80070057),
-                    unchecked((int)0x8000ffff),
-                    -1,
-                    1,
-                    2
-                };
+                unchecked((int)0x80004001),
+                unchecked((int)0x80004003),
+                unchecked((int)0x80070005),
+                unchecked((int)0x80070057),
+                unchecked((int)0x8000ffff),
+                -1,
+                1,
+                2
+            };
 
             foreach (var hr in hrs)
             {
                 Assert.Equal(hr, this.server.Return_As_HResult(hr));
                 Assert.Equal(hr, this.server.Return_As_HResult_Struct(hr).hr);
             }
         }
+
+        private void VerifyHelpLink()
+        {
+            string helpLink = "C:\\Windows\\system32\\dummy.hlp";
+            uint helpContext = 5678;
+            var ex = Assert.Throws<COMException>(() => { this.server.Throw_HResult_HelpLink(unchecked((int)-1), helpLink, helpContext); });
+            Assert.Equal($"{helpLink}#{helpContext}", ex.HelpLink);
+        }
     }
 }

src/tests/Interop/COM/NETServer/ErrorMarshalTesting.cs

@@ -30,4 +30,13 @@ public Server.Contract.HResult Return_As_HResult_Struct(int hresultToReturn)
     {
         return new Server.Contract.HResult { hr = hresultToReturn };
     }
+
+    public void Throw_HResult_HelpLink(int hresultToReturn, string helpLink, uint helpContext)
+    {
+        Marshal.GetExceptionForHR(hresultToReturn);
+
+        Exception e = Marshal.GetExceptionForHR(hresultToReturn);
+        e.HelpLink = $"{helpLink}#{helpContext}";
+        throw e;
+    }
 }

src/tests/Interop/COM/NativeClients/Primitives/ErrorTests.cpp

@@ -75,6 +75,48 @@ namespace
             THROW_FAIL_IF_FALSE(hr == hrMaybe);
         }
     }
+
+    void VerifyHelpContext(_In_ IErrorMarshalTesting *et)
+    {
+        ::printf("Verify expected helplink and context\n");
+
+        HRESULT hrs[] =
+        {
+            E_NOTIMPL,
+            E_POINTER,
+            E_ACCESSDENIED,
+            E_INVALIDARG,
+            E_UNEXPECTED,
+            HRESULT{-1},
+            S_FALSE,
+            HRESULT{2}
+        };
+
+        BSTR helpLink = SysAllocString(OLESTR("C:\\Windows\\system32\\dummy.hlp"));
+
+        for (int i = 0; i < ARRAY_SIZE(hrs); ++i)
+        {
+            HRESULT hr = hrs[i];
+            DWORD helpContext = (DWORD)(i + 0x1234);
+            HRESULT hrMaybe = et->Throw_HResult_HelpLink(hr, helpLink, helpContext);
+            THROW_FAIL_IF_FALSE(hr == hrMaybe);
+
+            IErrorInfo* pErrInfo;
+            THROW_IF_FAILED(GetErrorInfo(0, &pErrInfo));
+
+            BSTR helpLinkMaybe;
+            THROW_IF_FAILED(pErrInfo->GetHelpFile(&helpLinkMaybe));
+            THROW_FAIL_IF_FALSE(VarBstrCmp(helpLink, helpLinkMaybe, LANG_ENGLISH, 0) == VARCMP_EQ);
+            SysFreeString(helpLinkMaybe);
+
+            DWORD helpContextMaybe;
+            THROW_IF_FAILED(pErrInfo->GetHelpContext(&helpContextMaybe));
+            THROW_FAIL_IF_FALSE(helpContext == helpContextMaybe);
+            pErrInfo->Release();
+        }
+
+        SysFreeString(helpLink);
+    }
 }
 
 void Run_ErrorTests()
@@ -89,4 +131,5 @@ void Run_ErrorTests()
     VerifyExpectedException(errorMarshal);
     VerifyReturnHResult(errorMarshal);
     VerifyReturnHResultStruct(errorMarshal);
+    VerifyHelpContext(errorMarshal);
 }

src/tests/Interop/COM/NativeServer/ErrorMarshalTesting.h

@@ -26,6 +26,25 @@ class ErrorMarshalTesting : public UnknownImpl, public IErrorMarshalTesting
         return hresultToReturn;
     }
 
+    DEF_FUNC(Throw_HResult_HelpLink)(
+        /*[in]*/ int hresultToReturn,
+        /*[in]*/ BSTR helpLink,
+        /*[in]*/ DWORD helpContext)
+    {
+        ICreateErrorInfo* pCreateErrInfo;
+        CreateErrorInfo(&pCreateErrInfo);
+        pCreateErrInfo->SetHelpFile(helpLink);
+        pCreateErrInfo->SetHelpContext(helpContext);
+
+        IErrorInfo* pErrInfo;
+        pCreateErrInfo->QueryInterface(IID_IErrorInfo, (void**)&pErrInfo);
+        SetErrorInfo(0, pErrInfo);
+        pErrInfo->Release();
+        pCreateErrInfo->Release();
+
+        return HRESULT{ hresultToReturn };
+    }
+
 public: // IUnknown
     STDMETHOD(QueryInterface)(
         /* [in] */ REFIID riid,

src/tests/Interop/COM/ServerContracts/Server.Contracts.cs

@@ -201,6 +201,8 @@ public interface IErrorMarshalTesting
 
         [PreserveSig]
         HResult Return_As_HResult_Struct(int hresultToReturn);
+
+        void Throw_HResult_HelpLink(int hresultToReturn, string helpLink, uint helpContext);
     }
 
     public enum IDispatchTesting_Exception

src/tests/Interop/COM/ServerContracts/Server.Contracts.h

@@ -375,6 +375,10 @@ IErrorMarshalTesting : IUnknown
         /*[in]*/ int hresultToReturn ) = 0;
       virtual int STDMETHODCALLTYPE Return_As_HResult_Struct (
         /*[in]*/ int hresultToReturn ) = 0;
+      virtual HRESULT STDMETHODCALLTYPE Throw_HResult_HelpLink (
+        /*[in]*/ int hresultToReturn,
+        /*[in]*/ BSTR helpLink,
+        /*[in]*/ DWORD helpContext ) = 0;
 };
 
 enum IDispatchTesting_Exception