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IDProjectCategoryView StatusDate SubmittedLast Update
0008154CMakeCMakepublic2008-11-24 13:372011-06-17 12:39
ReporterRoscoe A. Bartlett 
Assigned ToDavid Cole 
PrioritynormalSeverityminorReproducibilityalways
StatusclosedResolutionfixed 
PlatformOSOS Version
Product VersionCMake-2-6 
Target VersionCMake 2.8.5Fixed in VersionCMake 2.8.5 
Summary0008154: LIST(REMOVE_DUPLICATES VARNAME) creates a local variable when passed a global varaible
DescriptionAfter about two hours of debugging, I found out that LIST(REMOVE_DUPLICATES VARNAME) will create a regular scoped local varaible VARNAME when passed a global (i.e. CACHE INTERNAL) variable VARNAME. This is not what I expected. To get around this, I wrote the following macro(s):

==============================================================================

FUNCTION(ASSERT_DEFINED VARIBLE_NAME)
  IF(NOT DEFINED ${VARIBLE_NAME})
    MESSAGE(SEND_ERROR "Error, the varible ${VARIBLE_NAME} is not defined!")
  ENDIF()
ENDFUNCTION()

MACRO(GLOBAL_SET VARNAME)
  SET(${VARNAME} ${ARGN} CACHE INTERNAL "")
ENDMACRO()

FUNCTION(REMOVE_GLOBAL_DUPLICATES VARNAME)
  ASSERT_DEFINED(${VARNAME})
  IF (${VARNAME})
    SET(TMP ${${VARNAME}})
    LIST(REMOVE_DUPLICATES TMP)
    GLOBAL_SET(${VARNAME} ${TMP})
  ENDIF()
ENDFUNCTION()

# 2008/11/21: rabartl: The above function is necessary in order to
# preserve the "global" natrue of the variable. If you just call
# LIST(REMOVE_DUPLICATES ...) it will actually create a local variable
# of the same name and shadow the global varible. It took me something
# like two hours to track down that bug!

==============================================================================

There is no mention of this type of behavior at:

    http://www.cmake.org/cmake/help/cmake2.6docs.html#command:list [^]

I am assuming this is a bug and not designed behavior.
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  Notes
(0019001)
David Cole (manager)
2009-12-28 15:35

 Brad, what do you think about this....? It seems to me that any CMake command that creates a variable should, in the context of a function, create a local variable... So this is actually acting correctly.

What do you think?
(0019021)
Brad King (manager)
2010-01-04 10:32

 It is an implementation artifact that list() reads from CACHE entries at all. The command was only intended to work with local variables. We should clarify the documentation. Only commands that document CACHE support can set cache entries.
(0025319)
David Cole (manager)
2011-02-07 17:22

 Fix pushed to 'next'
http://cmake.org/gitweb?p=cmake.git;a=commitdiff;h=2d14b15ec22a83ef78b0b9f1e5947f281e35d11a [^]

This behavior is as intended. More by organic growth than by design, really, but nevertheless, it's working as it's supposed to. The fix here is simply to clarify the situation in the LIST command's documentation.
(0026724)
David Cole (manager)
2011-06-06 18:25

 Closing resolved issues that have not been updated in more than 3 months.

 Issue History
Date Modified Username Field Change
2008-11-24 13:37 Roscoe A. Bartlett New Issue
2009-09-23 10:26 Bill Hoffman Status new => assigned
2009-09-23 10:26 Bill Hoffman Assigned To => David Cole
2009-12-28 15:34 David Cole Assigned To David Cole => Brad King
2009-12-28 15:35 David Cole Note Added: 0019001
2010-01-04 10:32 Brad King Note Added: 0019021
2010-01-04 10:32 Brad King Assigned To Brad King => David Cole
2011-02-07 17:22 David Cole Note Added: 0025319
2011-02-07 17:22 David Cole Status assigned => resolved
2011-02-07 17:22 David Cole Resolution open => fixed
2011-02-16 11:45 David Cole Target Version => CMake 2.8.5
2011-06-06 18:25 David Cole Status resolved => closed
2011-06-06 18:25 David Cole Note Added: 0026724
2011-06-17 12:39 David Cole Fixed in Version => CMake 2.8.5

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