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Q142594: INFO: Caveats for Using Empty Top-Level Projects in Dev. Studio

Article: Q142594
Product(s): Microsoft C Compiler
Version(s): 4.0,4.1,4.2,5.0,6.0
Operating System(s): 
Keyword(s): kbide kbVC400 kbVC410 kbVC420 kbVC500 kbVC600 kbGrpDSTools
Last Modified: 04-MAY-2002

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The information in this article applies to:

- Microsoft Visual C++, 32-bit Editions, versions 4.0, 4.1 
- Microsoft Visual C++, 32-bit Enterprise Edition, versions 4.2, 5.0, 6.0 
- Microsoft Visual C++, 32-bit Professional Edition, versions 4.2, 5.0, 6.0 
- Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
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SUMMARY
=======

This article discusses the process needed to set up a project workspace such
that it builds multiple targets that are related. You might want to do this if,
for example, you want to set up a workspace to build several related .exe files,
and .dll files that they can call. This scenario is described in the Visual C++
User's Guide online documentation in the "Empty Top-Level Project with Multiple
Subprojects" section.

The section of the documentation includes a sample scenario where an empty
top-level project has two subprojects that build .exe files, and one of the .exe
projects has a subproject that builds a DLL. The description of this scenario
implies that in general you can set up a top-level project that has no source
files, and it implies that the type of the top-level project and the subprojects
involved are unimportant; they can be any type. This is not the case. The types
of the projects and subprojects involved are important.

MORE INFORMATION
================

In certain scenarios, you get the following messages in the output window when
you set the default project configuration to the empty top-level project in
order to build all the subprojects:

  LINK : warning LNK4001: no object files specified; libraries used
  LINK : error LNK2001: unresolved external symbol _mainCRTStartup
  fatal error LNK1120: 1 unresolved externals
  Error executing link.exe.

This happens if you have one or more static library or DLL projects that are
immediate subprojects of the empty top-level project. Or, if the top-level
project is a DLL and the subproject is a resource-only DLL, the following error
will appear:

  Fatal Error C1001 Internal Compiler Error Compiler File MSC1.CPP Line 1786

Developer Studio invokes the linker to build an output file for the top-level
project and automatically tries to link with the library files built by the
subprojects (DLL subprojects create import libraries). This behavior occurs even
if the top-level project is empty, meaning that it does not include source
files.

If you want to set up a project workspace where the static library or DLL
projects are immediate subprojects of an empty top-level project, you need to
make the top-level project type be Makefile. In addition, you need to change the
build settings for the Makefile project so the Build command line setting is
blank. In other words, you do not want Developer Studio to invoke any command
for the empty top-level project. This allows you to set up the correct
dependency relationship between the top-level project and its subprojects, and
it prevents Developer Studio from attempting to create an output file for the
top-level project.

With Visual C++ 5.0 where the DLL projects are immediate subprojects of an empty
top-level project, you can select the Ignore export library check box in the
project settings for the DLL subprojects, Link tab, General category. This tells
the build system not to automatically link the empty top-level project with the
import library generated by the DLL subprojects. This check box is not available
for static libraries.

Additional query words: checkbox

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Keywords          : kbide kbVC400 kbVC410 kbVC420 kbVC500 kbVC600 kbGrpDSTools 
Technology        : kbVCsearch kbVC400 kbAudDeveloper kbVC410 kbVC420 kbVC500 kbVC600 kbVC32bitSearch kbVC500Search
Version           : :4.0,4.1,4.2,5.0,6.0
Issue type        : kbinfo

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