PRB: Unwanted Rebuilds Occur When Using NMAKE or Visual C++

• The development environment and Program Maintenance Utility (NMAKE.EXE) included with: - Microsoft Visual C++ for Windows, versions 1.0, 1.5, 1.51 - Microsoft Visual C++, 32-bit Edition, versions 1.0, 2.0, 2.1, 4.0, 5.0 - Microsoft FORTRAN PowerStation, 32-bit Edition, versions 1.0, 4.0

SYMPTOMS

When building a project, the development environment suddenly executes a Rebuild All command or unnecessarily recompiles specific object modules. Alternatively, after rebuilding and then trying to debug your program you may receive the message

"One or more targets are out of date or do not exist"

This happens when you are building from within the integrated development environment provided with the Microsoft products listed at the beginning of this article or when you are using the NMAKE.EXE utility.

CAUSE

The time on one of your dependency files is later than one of the output files linked to the dependency.

The build engine checks the time and date stamp of all files that have dependencies in the makefile. Files included in the project list are considered "dependencies." System- and user-created .H files included in the source files with #include statements are also considered dependencies. If the time and date of a dependency file is later than the time and date of a target file, then the target is automatically rebuilt.

RESOLUTION

The following five scenarios can cause this unwanted behavior. Resolve the issue by revising any of the following scenarios that fit your situation.

1. The time and/or date on your computer is not correct or was not correct when Visual C++ or the project in question was written to disk. The time and date of the targets and/or dependencies end up being earlier than the time and date when Visual C++ was installed.

   For example:

   a. You install Visual C++ when the date on the computer is

         2/1/94 12:00 PM.
   

   b. You change the date to 1/1/94 at 12:00 AM.

   c. You try to build a sample application. The .OBJ and .EXE files are

         written with the date 1/1/94 and some time. All the Visual C++ header
         files are dated later than the target .OBJ and .EXE files. If any of
         these headers are included as dependencies, the project will always
         be rebuilt.
   

   The fix is to either change the date on the computer to be later then that of any other files that are included in the project or to "touch" (rewrite the time and date) every dependency file in the build process. Ideally you should set the correct time and date on the computer and reinstall Visual C++.

2. You have enabled network caching or the network writes out files only after a certain time period.

   This causes a problem if you modify a file in the build dependencies that is stored on the network, save it, and then initiate a build. The network does not use the time stamp when you issued the save command but rather when the network actually writes the file.

   For example, you save a DEPEND.H file on the network, and then start a build on the local drive. The time is 1:00 PM. The network does not write DEPEND.H to the network disk right away because of caching. The changes made are presumably seen in the build, however, because the reads and writes to the file are serviced by the network, which uses the image in network cache memory. The build finishes and the output file ALLDONE.EXE file is written to the local drive at 1:05PM. Then at 1:10PM, DEPEND.H is flushed to the network disk.

   If the network uses the time that DEPEND.H was actually rewritten to disk (1:10) and not the when the user actually issued the save command (1:00), a rebuild of all files dependent on DEPEND.H will occur.

3. You are using some files over a network and the time and date on the local computer and the server differ now or did differ at one time.

   This is a variation of the two previous problems. The time stamp of the output files on one location are earlier than the dependency files seen on the other location. Synchronize the time on your local machine with the network time, synchronize all of the file times, and rebuild.

4. A dependency file is deleted but the dependencies were not updated.

   For example, the TEST.H file is listed as a dependency but it has been deleted and is no longer included in any source files. If the dependencies are not updated, everything that was dependent on TEST.H is rebuilt every time.

   With Visual C++ version 5.0, dependencies are updated every time the project is built using either Build, Rebuild All, or Batch Build. Dependencies for C and C++ files are generated by the C/C++ compiler during the build process. Dependencies for other types of source files are generated by the build system's dependency scanner.

5. Some type of corruption causes the date of a dependency file to be later than the output files.

STATUS

This behavior is by design.

Keywords          : NmakeIss VwbIss
Version           : WINDOWS:1.0,1.5,1.51;WINDOWS NT:1.0,2.0,2.1,4.0,5.0
Platform          : NT WINDOWS
Issue type        : kbprb