I don't have much to say except that ccmake behaves the same as
cmake-gui in this case.
You can add this at the end to see it.
set(MYSTATUS ${CMAKE_CXX_COMPILER_WORKS} CACHE STRING "")
Clint
On 07/15/2009 07:33 PM, Alan W. Irwin wrote:
Here is a simple CMakeLists.txt test case that reveals what I believe
is a
cmake-gui language bug.
# stanza 1
project(test NONE)
cmake_minimum_required(VERSION 2.6.4)
# stanza 2
include(CMakeDetermineCXXCompiler)
message(STATUS "CMAKE_CXX_COMPILER = ${CMAKE_CXX_COMPILER}")
#stanza 3
enable_language(CXX OPTIONAL)
message(STATUS "CMAKE_CXX_COMPILER_WORKS = ${CMAKE_CXX_COMPILER_WORKS}")
For the cmake application I get (in part)
The CXX compiler identification is GNU
CMAKE_CXX_COMPILER = /usr/bin/c++
CMAKE_CXX_COMPILER_WORKS = 1
For the cmake-gui application I get (in part)
The CXX compiler identification is GNU
CMAKE_CXX_COMPILER = /usr/bin/c++
CMAKE_CXX_COMPILER_WORKS =
Notice that CMAKE_CXX_COMPILER_WORKS is not defined for the cmake-gui
case.
If I remove the second stanza above, I get
CMAKE_CXX_COMPILER_WORKS = 1
for both cmake and cmake-gui.
Is this a cmake-gui bug or is it a bad idea to (semi-redundantly) run
include(CMakeDetermineCXXCompiler)
before
enable_language(CXX OPTIONAL)
Here is my use case for why I need to use the above pattern for our
PLplot
builds.
As I have reported before on list as well as at
http://public.kitware.com/Bug/view.php?id=9220, OPTIONAL does not work
correctly for enable_language. If the compiler is missing or
broken, enable_language _always_ errors out regardless of OPTIONAL.
Thus, no
soft landing (i.e., give a warning message and disable the component
of the
PLplot build that depends on the compiler and continuing) is yet possible
based on the value of CMAKE_<language>_COMPILER_WORKS (for any language
supported by CMake) derived in the third stanza above.
In the PLplot case I have worked around this bug by using stanzas
similar to
the second stanza above to obtain CMAKE_<language>_COMPILER. Thus, at
least
with this method I get a soft landing if the compiler is completely
missing
rather than erroring out in enable_language(CXX OPTIONAL) before
I can generate a soft landing based on CMAKE_CXX_COMPILER_WORKS. The
method
works fine for all our compiled languages (Ada, C++, D, Fortran, and
Java)
that are optionally enabled beyond the basic C language that we need
for our core library.
But then one of our developers made the mistake of trying cmake-gui which
left CMAKE_<language>_COMPILER_WORKS undefined in all cases and which
therefore caused many build problems. I can hack around that
cmake-gui bug
by simply setting CMAKE_<language>_COMPILER_WORKS to ON after every
enable_language(<language> OPTIONAL) call (i.e., take advantage of the
erroring out so assume everything is fine if it returns at all), but this
workaround on top of a workaround is just getting ridiculous!
Here is the summary.
I. cmake-gui should give the same CMAKE_<language>_COMPILER_WORKS
result as
cmake unless there is some reason to never use
include(CMakeDetermine<language>Compiler)
before
enable_language(<language> OPTIONAL)
If the CMake developers agree that this combination should work for the
cmake-gui application just like it does for the cmake application (i.e.,
this is a cmake-gui bug) I will put it in the bug tracker, but I hope it
does not languish there.
II. Even more importantly, I would like to see some action on the
above bug
9220. The CMakeDetermine<language>Compiler workaround should not be
necessary for the missing compiler case, and that workaround does not
cover
the broken compiler case. Soft landings for both cases are important for
projects with more than one language component such as PLplot.
Alan
__________________________
Alan W. Irwin
Astronomical research affiliation with Department of Physics and
Astronomy,
University of Victoria (astrowww.phys.uvic.ca).
Programming affiliations with the FreeEOS equation-of-state
implementation
for stellar interiors (freeeos.sf.net); PLplot scientific plotting
software
package (plplot.org); the libLASi project (unifont.org/lasi); the
Loads of
Linux Links project (loll.sf.net); and the Linux Brochure Project
(lbproject.sf.net).
__________________________
Linux-powered Science
__________________________
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