Put everything the user needs to link to the opm-core library into the
config-mode file, including result of probes. If this conflicts with
other packages, that is a configuration issue that must be resolved
anyway.
The advantage of doing it like this is that the user can build against
the library without knowing how it was configured; the only thing that
must be provided is the path to the config-mode module!
We need the list of variables to put in config.h for the CMake config-
mode module; reuse the code that writes the list to config.h in the
first place to also write CMake-compatible lines.
This makes it easier to write this list to the config-mode module and
let it merge with those from dependencies in the user's program
(although that implies that we no longer pretend that inconsistencies
are not possible).
The convention that singular form contains values for this project
alone whereas plural form contains values for both this project and
dependencies, is used.
Allow arguments to be used on the list of dependencies, this facilitates
searching for things like e.g. Boost, and there is now only need for one
list since REQUIRED can be one of the arguments.
Modules that starts with the prefix "Use" alters the build to enable
something by default, whereas modules that only provide functionality
is not common to start with that prefix.
If the library is not found, we will now get a message that the test
program failed to link because of a missing symbol, instead of an error
message from CMake that we tried to add -NOTFOUND libraries.
CMAKE_REQUIRED_FLAGS is intended to be added only to the compile for the
next probe, and inside an cmake_push_check_state/cmake_pop_check_state
guard. If we add it to the main flags (CMAKE_CXX_FLAGS), it will also be
added to subsequent checks, so it suffices.
If the package is installed at system standard location (such as
/usr or /usr/local), the headers will be located in the include
subdirectory and not under the root.
This find module is provided to help user programs locate an opm-core
library installation on their system; it is not used by opm-core itself.
Note that it has a direct dependency on the UseOpmFind and UseOpmPackage
helper modules; these must be in the CMAKE_MODULE_PATH also.
Instead of adding a package's standard variables to the project, it may
be desirable to be able to specify the prefix of the variables to add
them to, so the macro find_and_append can also be used in find modules.
Some older packages, and notably those that are detected by PkgConfig,
only give library names and then a list of library search directories.
Add to link_directories here in order to support this configuration,
even though it is deprecated in newer versions of CMake.
Users should be able to point their opm-core_DIR to the build tree of
this project and have their client programs pick up all the necessary
settings to use the library. The config mode file helps to bridge
variables from one build (of opm-core) to another (of client program).
In this stage of development it is assumed that having a build that is
easy to debug from within an IDE has the most value for most users.
If any speed comparisons are to be done, be sure to configure with
-DCMAKE_BUILD_TYPE=Release
Always include debug symbols in the build, and strip them to a separate
file after compiling. The GNU debugger will automatically pick up the
external debug symbols due to a link we put in the executable.
Having debug symbols do not affect the level of optimization in the GNU
toolchain.
If the program is built out-of-source-tree then the configuration file
(which is generated and not part of the source) will not be available
relative to the source code file.
Search for known headers and library files that indicates that DUNE is
available on the system, and setup compiler and linker variables.
Unfortunately, this module has hard-coded some knowledge of the
dependencies on other modules, and knowledge of which symbols that
should be defined. This information must be revised whenever a new
version of DUNE is released, because it is hard and error-prone to
infer this automatically.
As for the name of the modules, see the comment by mblatt at 2012-05-22
in the thread about CMake evaluation in the DUNE user forum:
<http://www.dune-project.org/flyspray/index.php?do=details&task_id=1000>
Search for modules in this library in the same style as Boost; by
specifying a list of components. If all on the list is present, then
a list of libraries to link with, is returned.
BOOST_TEST_DYN_LINK must be defined if you are *building* Boost::Test as
a shared object, and the client programs must also include this option
when they use the header files, to link to it correctly.
Normally a package returns a set of standard variables such as
Xxx_INCLUDE_DIRS. Adding this to a list that is collected for the
project amounts to a bunch of boilerplate which can rather be
encapsulated in a macro.
We want to compile with the -std=c++0x since DUNE uses this settings and
we need to use the same ABI as that one if we are going to link with it.
Find module is a copy of the one in cmake/modules in (the cmake branch of)
dune-common.
Some files are distributed with the source, but does not end up in the
final shared object. These files are captured by the glob, so we have
to remove them afterwards. (There are fewer of these files than
explicitly list all files that should be included in the build).
