short-description: Dependencies for external libraries and frameworks ...
Very few applications are fully self-contained, but rather they use external libraries and frameworks to do their work. Meson makes it very easy to find and use external dependencies. Here is how one would use the zlib compression library.
zdep = dependency('zlib', version : '>=1.2.8')
exe = executable('zlibprog', 'prog.c', dependencies : zdep)
First Meson is told to find the external library zlib
and error out
if it is not found. The version
keyword is optional and specifies a
version requirement for the dependency. Then an executable is built
using the specified dependency. Note how the user does not need to
manually handle compiler or linker flags or deal with any other
minutiae.
If you have multiple dependencies, pass them as an array:
executable('manydeps', 'file.c', dependencies : [dep1, dep2, dep3, dep4])
If the dependency is optional, you can tell Meson not to error out if the dependency is not found and then do further configuration.
opt_dep = dependency('somedep', required : false)
if opt_dep.found()
# Do something.
else
# Do something else.
endif
You can pass the opt_dep
variable to target construction functions
whether the actual dependency was found or not. Meson will ignore
non-found dependencies.
Meson also allows to get variables that are defined in the
pkg-config
file. This can be done by using the
get_pkgconfig_variable
function.
zdep_prefix = zdep.get_pkgconfig_variable('prefix')
These variables can also be redefined by passing the define_variable
parameter, which might be useful in certain situations:
zdep_prefix = zdep.get_pkgconfig_variable('libdir', define_variable: ['prefix', '/tmp'])
The dependency detector works with all libraries that provide a
pkg-config
file. Unfortunately several packages don't provide
pkg-config files. Meson has autodetection support for some of these,
and they are described later in this page.
You can declare your own dependency objects that can be used interchangeably with dependency objects obtained from the system. The syntax is straightforward:
my_inc = include_directories(...)
my_lib = static_library(...)
my_dep = declare_dependency(link_with : my_lib,
include_directories : my_inc)
This declares a dependency that adds the given include directories and static library to any target you use it in.
Many platforms do not provide a system package manager. On these systems dependencies must be compiled from source. Meson's subprojects make it simple to use system dependencies when they are available and to build dependencies manually when they are not.
To make this work, the dependency must have Meson build definitions and it must declare its own dependency like this:
foo_dep = declare_dependency(...)
Then any project that wants to use it can write out the following
declaration in their main meson.build
file.
foo_dep = dependency('foo', fallback : ['foo', 'foo_dep'])
What this declaration means is that first Meson tries to look up the
dependency from the system (such as by using pkg-config). If it is not
available, then it builds subproject named foo
and from that
extracts a variable foo_dep
. That means that the return value of
this function is either an external or an internal dependency
object. Since they can be used interchangeably, the rest of the build
definitions do not need to care which one it is. Meson will take care
of all the work behind the scenes to make this work.
Some dependencies have specific detection logic.
Generic dependency names are case-sensitive1, but these dependency names are matched case-insensitively. The recommended style is to write them in all lower-case.
In some cases, more than one detection method exists, and the method
keyword
may be used to select a detection method to use. The auto
method uses any
checking mechanisms in whatever order meson thinks is best.
e.g. libwmf and CUPS provide both pkg-config and config-tool support. You can
force one or another via the method
keyword:
cups_dep = dependency('cups', method : 'pkg-config')
wmf_dep = dependency('libwmf', method : 'config-tool')
CUPS, LLVM, pcap, WxWidgets, libwmf, and GnuStep either do not provide pkg-config modules or additionally can be detected via a config tool (cups-config, llvm-config, etc). Meson has native support for these tools, and they can be found like other dependencies:
pcap_dep = dependency('pcap', version : '>=1.0')
cups_dep = dependency('cups', version : '>=1.4')
llvm_dep = dependency('llvm', version : '>=4.0')
Use the modules
keyword to list frameworks required, e.g.
dep = find_dep('appleframeworks', modules : 'foundation')
These dependencies can never be found for non-OSX hosts.
Boost is not a single dependency but rather a group of different libraries. To use Boost headers-only libraries, simply add Boost as a dependency.
boost_dep = dependency('boost')
exe = executable('myprog', 'file.cc', dependencies : boost_dep)
To link against boost with Meson, simply list which libraries you would like to use.
boost_dep = dependency('boost', modules : ['thread', 'utility'])
exe = executable('myprog', 'file.cc', dependencies : boost_dep)
You can call dependency
multiple times with different modules and
use those to link against your targets.
If your boost headers or libraries are in non-standard locations you can set the BOOST_ROOT, BOOST_INCLUDEDIR, and/or BOOST_LIBRARYDIR environment variables.
You can set the argument threading
to single
to use boost libraries that
have been compiled for single-threaded use instead.
method
may be auto
, config-tool
, pkg-config
or extraframework
.
This finds the OpenGL library in a way appropriate to the platform.
method
may be auto
, pkg-config
or system
.
GTest and GMock come as sources that must be compiled as part of your
project. With Meson you don't have to care about the details, just
pass gtest
or gmock
to dependency
and it will do everything for
you. If you want to use GMock, it is recommended to use GTest as well,
as getting it to work standalone is tricky.
You can set the main
keyword argument to true
to use the main()
function provided by GTest:
gtest_dep = dependency('gtest', main : true, required : false)
e = executable('testprog', 'test.cc', dependencies : gtest_dep)
test('gtest test', e)
(added 0.44.0)
method
may be auto
, config-tool
or pkg-config
.
Meson has native support for LLVM going back to version LLVM version 3.5. It supports a few additional features compared to other config-tool based dependencies.
As of 0.44.0 Meson supports the static
keyword argument for LLVM. Before this
LLVM >= 3.9 would always dynamically link, while older versions would
statically link, due to a quirk in llvm-config
.
Meson wraps LLVM's concept of components in it's own modules concept. When you need specific components you add them as modules as meson will do the right thing:
llvm_dep = dependency('llvm', version : '>= 4.0', modules : ['amdgpu'])
As of 0.44.0 it can also take optional modules (these will affect the arguments generated for a static link):
llvm_dep = dependency(
'llvm', version : '>= 4.0', modules : ['amdgpu'], optional_modules : ['inteljitevents'],
)
(added 0.42.0)
MPI is supported for C, C++ and Fortran. Because dependencies are
language-specific, you must specify the requested language using the
language
keyword argument, i.e.,
dependency('mpi', language: 'c')
for the C MPI headers and librariesdependency('mpi', language: 'cpp')
for the C++ MPI headers and librariesdependency('mpi', language: 'fortran')
for the Fortran MPI headers and librariesMeson prefers pkg-config for MPI, but if your MPI implementation does
not provide them, it will search for the standard wrapper executables,
mpic
, mpicxx
, mpic++
, mpifort
, mpif90
, mpif77
. If these
are not in your path, they can be specified by setting the standard
environment variables MPICC
, MPICXX
, MPIFC
, MPIF90
, or
MPIF77
, during configuration.
(added 0.46.0)
This dependency selects the appropriate compiler flags and/or libraries to use for OpenMP support.
The language
keyword may used.
(added 0.42.0)
method
may be auto
, config-tool
or pkg-config
.
Python3 is handled specially by meson:
pkg-config
.pkg-config
fails meson uses a fallback:
python3
interpreter./Library/Frameworks
.Note that python3
found by this dependency might differ from the one used in
python3
module because modules uses the current interpreter, but dependency tries
pkg-config
first.
method
may be auto
, extraframework
, pkg-config
or sysconfig
Meson has native Qt support. Its usage is best demonstrated with an example.
qt5_mod = import('qt5')
qt5widgets = dependency('qt5', modules : 'Widgets')
processed = qt5_mod.preprocess(
moc_headers : 'mainWindow.h', # Only headers that need moc should be put here
moc_sources : 'helperFile.cpp', # must have #include"moc_helperFile.cpp"
ui_files : 'mainWindow.ui',
qresources : 'resources.qrc',
)
q5exe = executable('qt5test',
sources : ['main.cpp',
'mainWindow.cpp',
processed],
dependencies: qt5widgets)
Here we have an UI file created with Qt Designer and one source and
header file each that require preprocessing with the moc
tool. We
also define a resource file to be compiled with rcc
. We just have to
tell Meson which files are which and it will take care of invoking all
the necessary tools in the correct order, which is done with the
preprocess
method of the qt5
module. Its output is simply put in
the list of sources for the target. The modules
keyword of
dependency
works just like it does with Boost. It tells which
subparts of Qt the program uses.
Setting the optional private_headers
keyword to true adds the private header
include path of the given module(s) to the compiler flags. (since v0.47.0)
Note using private headers in your project is a bad idea, do so at your own risk.
method
may be auto
, pkgconfig
or qmake
.
SDL2 can be located using pkg-confg
, the sdl2-config
config tool, or as an
OSX framework.
method
may be auto
, config-tool
, extraframework
or pkg-config
.
This dependency selects the appropriate compiler flags and/or libraries to use for thread support.
See threads.
Meson will find valgrind using pkg-config
, but only uses the compilation flags
and avoids trying to link with it's non-PIC static libs.
(added 0.42.0)
Vulkan can be located using pkg-config
, or the VULKAN_SDK
environment variable.
method
may be auto
, pkg-config
or system
.
Similar to Boost, WxWidgets is not a single library but rather
a collection of modules. WxWidgets is supported via wx-config
.
Meson substitutes modules
to wx-config
invocation, it generates
compile_args
using wx-config --cxxflags $modules...
link_args
using wx-config --libs $modules...
wx_dep = dependency(
'wxwidgets', version : '>=3.0.0', modules : ['std', 'stc'],
)
# compile_args:
$ wx-config --cxxflags std stc
# link_args:
$ wx-config --libs std stc
1: They may appear to be case-insensitive, if the
underlying file system happens to be case-insensitive.