Getting MIDL 2003 Redefinition errors

Question

I have a very simple program that I am trying to compile before I build it out any further. I am trying to learn COM so following along here, I create app.h and app.cpp file in VS 2017 and using the ATL Template. When I try to build the solution I get a lot of MIDL 200 redefinition errors.

UPDATE (Based on @Roman R.'s response) Note that if I used cl /LD app.cpp on a Dev Command Line, I am able to generate app.dll correctly. The MIDL 2003 redefinition errors show up only when trying to build the solution through Visual Studio. I am working with VS 2017 Community edition, so not sure if other versions of Visual Studio have the same problem.

My Include path is simply inherited from the parent defaults i.e. the standard $(VC_IncludePath) and $(WindowsSDK_IncludePath). My Windows SDK version is 10.0.17763.0 and MSVC version is 14.16.27023

//app.h
#pragma once
#define STRICT
#ifndef _WINVER
    #define _WINVER 0x0A00
#endif

#ifndef _WIN32_WINNT
    #define _WIN32_WINNT 0x0A00
#endif



#define _USRDLL
#define _ATL_ATTRIBUTES
#define _ATL_APARTMENT_THREADED
#define _ATL_NO_AUTOMATIC_NAMESPACE

#include <SDKDDKVer.h>
#include <atlbase.h>
#include <atlcom.h>
#include <atlwin.h>
#include <atltypes.h>
#include <atlctl.h>
#include <atlhost.h>
using namespace ATL;

//app.cpp
#include "app.h"

[module(dll, name = "app", helpstring = "APP 1.0 Type Library")];
[emitidl];

When I try to build the solution, I get a lot of MIDL2003 errors; snippet from Debug\app.log below:

  Microsoft (R) 32b/64b MIDL Compiler Version 8.01.0622 
  Copyright (c) Microsoft Corporation. All rights reserved.
  Processing .\vc140.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\shared\wtypes.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\shared\wtypesbase.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\shared\basetsd.h
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\shared\guiddef.h
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\wincrypt.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\prsht.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\objidl.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\unknwn.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\propidlbase.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\oaidl.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\urlmon.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\oleidl.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\servprov.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\msxml.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\propidl.idl
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(56): error MIDL2003: redefinition : tagVersionedStream
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(60): error MIDL2003: redefinition : PROPSETFLAG_DEFAULT
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(61): error MIDL2003: redefinition : PROPSETFLAG_NONSIMPLE
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(62): error MIDL2003: redefinition : PROPSETFLAG_ANSI
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(64): error MIDL2003: redefinition : PROPSETFLAG_UNBUFFERED
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(66): error MIDL2003: redefinition : PROPSETFLAG_CASE_SENSITIVE
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(70): error MIDL2003: redefinition : PROPSET_BEHAVIOR_CASE_SENSITIVE
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(90): error MIDL2003: redefinition : tagCAC
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(91): error MIDL2003: redefinition : tagCAUB
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(92): error MIDL2003: redefinition : tagCAI
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(93): error MIDL2003: redefinition : tagCAUI
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(94): error MIDL2003: redefinition : tagCAL
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(95): error MIDL2003: redefinition : tagCAUL
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(96): error MIDL2003: redefinition : tagCAFLT
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(97): error MIDL2003: redefinition : tagCADBL
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(98): error MIDL2003: redefinition : tagCACY
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(99): error MIDL2003: redefinition : tagCADATE
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(100): error MIDL2003: redefinition : tagCABSTR
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(101): error MIDL2003: redefinition : tagCABSTRBLOB
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(102): error MIDL2003: redefinition : tagCABOOL
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(103): error MIDL2003: redefinition : tagCASCODE
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(104): error MIDL2003: redefinition : tagCAPROPVARIANT
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(105): error MIDL2003: redefinition : tagCAH
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(106): error MIDL2003: redefinition : tagCAUH
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(107): error MIDL2003: redefinition : tagCALPSTR
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(108): error MIDL2003: redefinition : tagCALPWSTR
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(109): error MIDL2003: redefinition : tagCAFILETIME
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(110): error MIDL2003: redefinition : tagCACLIPDATA
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(111): error MIDL2003: redefinition : tagCACLSID
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(276): error MIDL2003: redefinition : tag_inner_PROPVARIANT
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(309): error MIDL2003: redefinition : PID_DICTIONARY
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(310): error MIDL2003: redefinition : PID_CODEPAGE
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(311): error MIDL2003: redefinition : PID_FIRST_USABLE
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(312): error MIDL2003: redefinition : PID_FIRST_NAME_DEFAULT
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(313): error MIDL2003: redefinition : PID_LOCALE
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(314): error MIDL2003: redefinition : PID_MODIFY_TIME
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(315): error MIDL2003: redefinition : PID_SECURITY
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(316): error MIDL2003: redefinition : PID_BEHAVIOR
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(317): error MIDL2003: redefinition : PID_ILLEGAL
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(319): error MIDL2003: redefinition : PID_MIN_READONLY
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(320): error MIDL2003: redefinition : PID_MAX_READONLY
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(322): error MIDL2003: redefinition : PRSPEC_INVALID
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(323): error MIDL2003: redefinition : PRSPEC_LPWSTR
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(324): error MIDL2003: redefinition : PRSPEC_PROPID
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(339): error MIDL2003: redefinition : tagPROPSPEC
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(348): error MIDL2003: redefinition : tagSTATPROPSTG
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(368): error MIDL2003: redefinition : tagSTATPROPSETSTG
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(377): error MIDL2003: redefinition : IPropertyStorage
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(509): error MIDL2003: redefinition : IPropertySetStorage
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(546): error MIDL2003: redefinition : IEnumSTATPROPSTG
c:\program files (x86)\windows kits\10\include\10.0.17763.0\um\propidlbase.idl(586): error MIDL2003: redefinition : IEnumSTATPROPSETSTG
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\ocidl.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\comcat.idl
  Processing C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.16.27023\atlmfc\include\atliface.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\oleacc.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\shtypes.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\MsHTML.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\dimm.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\dispex.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\shared\dxgitype.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\shared\dxgicommon.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\shared\dxgiformat.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\MsHtmHst.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\docobj.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\ExDisp.idl
  Processing C:\Program Files (x86)\Windows Kits\10\Include\10.0.17763.0\um\ObjSafe.idl
.\vc140.idl(38): warning MIDL2214: semantic check incomplete due to previous errors
LINK : fatal error LNK1240: failed to compile IDL content

score 0 · Accepted Answer · answered Dec 30 '18 at 09:57

0

First of all, using ATL attributes is not a good idea overall. You are referring to MSDN section which belongs to Visual Studio 2008, and ATL attributes were deprecated soon.

An edit of MyIncludes.h that worked for me with latest VS2017 (the rest is per the walkthrough steps):

#pragma once
#include <sdkddkver.h> // <<--- This is the actual edit compared to MSDN article
#define _USRDLL
#define _ATL_ATTRIBUTES
#define _ATL_APARTMENT_THREADED
#define _ATL_NO_AUTOMATIC_NAMESPACE
#include <atlbase.h>
#include <atlcom.h>
#include <atlwin.h>
#include <atltypes.h>
#include <atlctl.h>
#include <atlhost.h>
using namespace ATL;

answered Dec 30 '18 at 09:57

Roman R.

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I should have mentioned, my code does work when using `cl /LD app.cpp`, but throws the redefinition errors when doing a solution build in VS 2017. I should have been more explicit in the original post. To your other point about atl attributes, I don't really want to introduce them in new code, but not sure what I should use instead. Could you point me to something on MSDN that takes me down the correct path? Thanks for your insights :) – Cod.ie Dec 30 '18 at 16:04
Never mind, I got my answer. I'll just use Visual Studio ATL Project. I think I have a problem with VS 2017 because I wrote the `app.h` and `app.cpp` outside of it and then imported it into a VS 2017 solution. I ventured down this path because I was trying to explore if it is possible to do COM development without using Visual Studio (e.g. just use VSCode). That is still an interesting topic, but perhaps for another time. I'll mark the question answered. – Cod.ie Dec 30 '18 at 17:35

Getting MIDL 2003 Redefinition errors

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