During configuration some of the values for CMake properties (compiler
flags etc.) may be changed either by the user (through command line
parameters or option files), or by the configuration script itself
(setting more aggressive options or detailed debugging for instance).
This change writes many of the relevant values back into the cache so
they are available for introspection (using e.g. ccmake) or when the
rerunning the configuration without specifying all options.
Clang aims to be compatible with GCC when it comes to command-line
parameters. Where we enable functionality based on the presence of
a GCC-compiler, we can use the same functionality with Clang.
This patch introduces a new variable CXX_COMPAT_GCC which is true if
the compiler handles the same options as GCC, and this variable is
subsequently used in tests instead of CMAKE_COMPILER_IS_GNUCXX (which
remains if we need to test if we really have GCC, e.g. for version)
When checking out from source code, the paths that were used to
configure the project should be carried on to the installed binary,
so the same libraries are used without much effort.
By using RUNPATH instead of (just) RPATH, it can be overridden with
LD_LIBRARY_PATH if the user so desires.
If you just download the source, compile and install, you get the
release library. Users who want to develop the code, must do setup
in their environment.
Instead of having the name of the module set for each flag, use the
available standard option. Mixing shared objects and static libraries
in the same build is not a very realistic scenario anyway.
This enables us to call configure without actually having a particular
module; the script may then be used on a group level.
If support for OpenMP should be added, it must be specified by
setting an option. If not, then warnings for unknown pragmas are
disabled, so that the code can have #pragma omp witout getting
messages during build.
The probe for Boost was changed in CMake 2.8; if the system has
installed configuration files tailored for an older CMake, the
library paths are not setup correctly. This patch disables using
those configuration files; just use the library directly instead.
