[CMake] IMPORTANT!! SET CACHE FORCE not wortking with UNINITIALIZED variables

[Fernando Cacciola]

Hi,

Since my last post about this got unnoticed I'm reposting it, this time 
with additional information.

If you run cmake with a definition in the command-line, like so:

cmake -DVAR=123 .

in 2.6.2 that goes into the cache as an UNINITIALIZED variable:

VAR:UNINITIALIZED=123


And, since it is of UNINITIALIZED type, SET doesn't set the value 
indicated even if FORCE is used.

That is, with the following script:

SET( VAR "321" CACHE STRING "" FORCE )
MESSAGE( STATUS "VAR=${VAR}" )


Calling

  cmake -DVAR=123 .

prints

-- VAR=123

While calling

   cmake -DVAR:STRING=123 .

prints

-- VAR=321


The culprint is in the following section of the cmake sources:


void cmMakefile::AddCacheDefinition(const char* name, const char* value,
                                     const char* doc,
                                     cmCacheManager::CacheEntryType type)
{
   const char* val = value;
   cmCacheManager::CacheIterator it =
     this->GetCacheManager()->GetCacheIterator(name);
   if(!it.IsAtEnd() && (it.GetType() == cmCacheManager::UNINITIALIZED) &&
                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

      it.Initialized())
     {

     val = it.GetValue();
     ^^^^^^^^^^^^^^^^^^^^


As you can see, when SET sees an UNINITIALIZED variable it just ignores 
the value being passed on and just keeps the previous value.

IMO this is a bug, and I even wonder if that comparison didn't intend to 
be != instead  ??



Fortunately, the variable is nevertheless overwritten into the cache, 
with the old (wrong) value but the correct type, hence, the following 
works around the bug:


SET( VAR "321" CACHE STRING "" FORCE )
SET( VAR "321" CACHE STRING "" FORCE )
MESSAGE( STATUS "VAR=${VAR}" )

That is, the first SET "fixes" the type, allowing the second SET to do 
what it should.


Shall I add this to the tracker or is this behaviour on purpose??

TIA

Fernando Cacciola



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