FIX: Alpha MFC Regular DLL Fails After Porting from Intel

• Microsoft Visual C++, 32-bit Editions, versions 4.0, 4.0a on the following platforms: - Alpha

SYMPTOMS

When moving a Visual C++ 4.x MFC regular DLL (_USRDLL) project from the Intel platform to the Alpha RISC platform you may run into one or more of a set of related problems. Some symptoms are:

• CWinApp::InitInstance() is not called.
• Resources stored in the DLL fail to load because AfxGetResourceHandle or AfxFindResourceHandle returns NULL or an incorrect resource handle.
• AfxGetInstanceHandle() returns NULL.
• Standard MFC database, sockets, or OLE resources fail to load. For example, AfxLoadString(AFX_IDP_SQL_CONNECT_FAIL) returns an empty string, even when the Regular DLL is properly using the MFC Database classes.

CAUSE

When you create the Alpha configuration from an existing Intel based configuration, the Visual C++ development environment does not copy the /D _USRDLL compiler flag. This problem does not cause compiler or linker errors.

Without this symbol defined, the default non-MFC DllMain is used and MFC is not initialized.

RESOLUTION

Make sure that /D "_USRDLL" is in the compiler options for regular MFC DLLs. If not, add _USRDLL to the list of preprocessor definitions.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug was corrected in Visual C++ version 5.0.

REFERENCES

For more information covering MFC initialization in your Regular DLL, and other relevant topics, please see the following articles in the Microsoft Knowledge Base:

   ARTICLE-ID: Q140850
   TITLE     : HOWTO: Converting DLLTRACE to Use MFC in Shared Library

   ARTICLE-ID: Q154126
   TITLE     : PRB: Using Extension DLL, Database/OLE/Sockets in Regular
               DLL