On 08/16/2007 01:42 PM, Maik Beckmann wrote:
Am Donnerstag, 16. August 2007 20:10:48 schrieb Larry Evans:
I tried this by creating a top-level build directory, built-by, with subdirectories:
g++-4.1 #the "regular" compiler g++-4.3_v #the "variadic" compiler
For 4.3_v, I had to first do `cmake <path-to-source>` then edit the g++-4.3_v/CMakeCache.txt to include the lines:
//CXX compiler. CMAKE_CXX_COMPILER:FILEPATH=/home/evansl/download/gcc/variadic-templates/gc c-4.3-20070323/install/bin/g++
//Flags used by the compiler during all build types. CMAKE_CXX_FLAGS:STRING=-std=gnu++0x
The FLAGS value was needed, as you know, to enable variadic templates.
However, after I tried `make` the value of COMPILER:FILEPATH was reverted back to /usr/bin/g++ by something. How can that reversion be prevented or is there a better way to cause the variadic compiler to be used?
Hello Larry,
If you want to say CMake which compiler it has to use, you must give it via the matching environment variable (CXX for the c++ compiler, CC for c, FC for fortran) like: $ cd /path/to/builddir $ CXX=/home/evansl/download/gcc/variadic-templates\ /gcc-4.3-20070323/install/bin/g++ \ cmake /path/to/boost-cmake
Or, a more descriptive name than /path/to/boost-cmake would be $BOOST/src, which is what's used on: http://svn.boost.org/trac/boost/wiki/CMakeConfigAndBuild
Note: you have to remove CMakeCache.txt, if it exists.
OK, so, in order to emulate Boost.Build's command line interface as close as possible, the user would create a bash (or whatever shell) file which has the one line: CXX=/home/evansl/download/gcc/variadic-templates\ /gcc-4.3-20070323/install/bin/g++ \ cmake $BOOST/src The only reason for this, which in this case is important, is to save repeatedly typing the long command between source code edits and testing. I assume the CMAKE_CXX_FLAGS:STRING value from the CMakeCache.txt is used since I saw the error message when make was run: Scanning dependencies of target boost_iostreams-shared [ 2%] Building CXX object libs/iostreams/src/CMakeFiles/boost_iostreams-shared.dir/file_descriptor.o cc1plus: error: unrecognized command line option "-std=gnu++0x" make[2]: *** [libs/iostreams/src/CMakeFiles/boost_iostreams-shared.dir/file_descriptor.o] This is inconsistent because the FLAGS value is used from CMakeCache.txt, but the CXX_COMPILER is ignored and even overwritten. Why put the CXX_COMPILER assignment in the CMakeCache.txt file if it's ignored?
This behavior of CMake ensures that the results of the test CMake runs on the compiler are allway valid. Since the results are stored in CMakeLists.txt,
Which CMakeLists.txt? The following command: cd ~/prog_dev/boost-svn/ro/sandbox-branches/boost-cmake/src/ find . -name CMakeLists.txt -ls 5181833 12 -rw-r--r-- 1 evansl evansl 10169 Aug 13 16:16 ./libs/config/test/CMakeLists.txt ... shows no times later than yesterday; hence, it's unclear to me what 'results are stored in CMakeLists.txt' means. Could you please clarify?
you have to remove it, which triggers CMake to rerun the compiler tests.
Does 'it' refer to CMakeLists.txt or CMakeCache.txt?
Regards, Maik Beckmann
Thanks for the feedback! -regards, Larry