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Q119873: FIX: Incorrect Use of #pragma Pack Causes C1001 Errors

Article: Q119873
Product(s): Microsoft C Compiler
Version(s): 1.0,2.0,4.0,4.1,4.2,5.0,6.0
Operating System(s): 
Keyword(s): kbCompiler kbVC100bug kbVC200bug kbVC400bug kbVC410bug kbVC420bug kbVC500bug kbVC600bug
Last Modified: 16-MAY-2002

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The information in this article applies to:

- The C/C++ Compiler (CL.EXE), used with:
   - Microsoft Visual C++, 32-bit Editions, versions 1.0, 2.0, 4.0, 4.1, 4.2, 5.0, 6.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

When compiling code that uses #pragma pack() to pop an ID that has not been
pushed after successfully popping an ID that was pushed, the compilers listed
above will generate:

  fatal error C1001: INTERNAL COMPILER ERROR

In addition, this error will be followed by a message similar to

  (compiler file 'msc1.cpp', line 902)
  Please choose the Technical Support command on the Visual C++ Help menu, or
  open the Technical Support help file for more information

NOTE: In Microsoft Visual Studio .NET, you receive a C4160 warning instead of the
error message, so you can compile and run the program.

RESOLUTION
==========

Pop only IDs that have been previously pushed onto the compiler's internal
stack.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article.

This problem was corrected in Microsoft Visual C++ .NET.

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

The following sample code demonstrates the bug:

Sample Code
-----------

  /* packfail.c

  Compile options needed: none
  */ 

  #pragma pack(push, a)
  #pragma pack(push, b, 4)
  #pragma pack(pop, b)
  #pragma pack(pop, value)

Additional query words: kbVC400bug 8.00 9.00 buglist1.00 buglist2.00 buglist8.00 buglist9.00 10.00 10.10 10.20

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Keywords          : kbCompiler kbVC100bug kbVC200bug kbVC400bug kbVC410bug kbVC420bug kbVC500bug kbVC600bug kbNoUpdate 
Technology        : kbVCsearch kbAudDeveloper kbCVCComp
Version           : :1.0,2.0,4.0,4.1,4.2,5.0,6.0
Issue type        : kbbug
Solution Type     : kbfix

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