[CMake] ccmake gets all squirrelly over which C++ compiler to use.

[kent williams]

Version 2.6 patch 2 on OS X and Linux -- you know your code is
portable when the same issue happens on multiple platforms!

Here's the scenario -- a guy in our department was having trouble
getting ccmake to generate makefiles.

My diagnosis was pretty simple: His project depended on both ITK and
VTK. ITK had been compiled with and VTK had been compiled with
'/usr/bin/g++'.  So he got into an infinite loop where CMake would
force the CMAKE_CXX_COMPILER to '/usr/bin/c++' when it processed
UseITK.cmake, then when it processed UseVTK.cmake, it woud force it
back to '/usr/bin/g++'.  Then it would tell you it had to delete
CMakeCache.txt, and re-run the Configuration pass.

This turns the CCMake run into effectively an endless loop with a
human in the loop, endlessly trying to reconfigure.

The solution was obvious -- make sure both VTK and ITK use the same
compiler Of course on most machines /usr/bin/c++ is a symbolic link to
/usr/bin/g++ (or vice versa) but CCMake can't assume that's the
case...

But here is the real problem, the 'squirrelyness' referred to in the
subject line:

In ccmake, once VTK and ITK were built with the same compiler, I
changed CMAKE_CXX_COMPILER to match what VTK and ITK were reporting,
set ITK_DIR and VTK_DIR , and hit compile.

But again it would pop up a warning, and when I exited the warning
screen, CCMake had forgotten what I'd entered for CMAKE_CXX_COMPILER,
ITK_DIR, and VTK_DIR, so I had to type them in a second time.  Once I
did that, the Configure pass would finish and I could get through the
Generate pass.

This is one specific case, but I've noticed in general that if the
Configure pass has an error, it forgets everything you just entered
and you have to re-enter it, and fix the error, and Configure again.
This is extremely frustrating, like dying in a video game and having
to go back and re-run all levels to get back to where you died.

What's the story? Can this be fixed?