How do I do X in Meson?
This page lists code snippets for common tasks. These are written mostly using the C compiler, but the same approach should work on almost all other compilers.
When first running Meson, set it in an environment variable.
$ CC=mycc meson <options>
Note that environment variables like
CC only works in native builds.
CC refers to the compiler for the host platform, that is the
compiler used to compile programs that run on the machine we will
eventually install the project on. The compiler used to build things
that run on the machine we do the building can be specified with
CC_FOR_BUILD. You can use it in cross builds.
Note that environment variables are never the idiomatic way to do anything with Meson, however. It is better to use the native and cross files. And the tools for the host platform in cross builds can only be specified with a cross file.
There is a table of all environment variables supported Here
New in 0.53.0
Like the compiler, the linker is selected via the
<compiler variable>_LD environment variable, or through the
<compiler entry>_ld entry in a native or cross file. You must be aware of
whether you're using a compiler that invokes the linker itself (most
compilers including GCC and Clang) or a linker that is invoked
directly (when using MSVC or compilers that act like it, including
Clang-Cl). With the former
CC_LD should be the value to
pass to the compiler's special argument (such as
-fuse-ld with clang
and gcc), with the latter it should be an executable, such as
NOTE In Meson 0.53.0 the
ld entry in the cross/native file and the
LD environment variable were used, this resulted in a large number
of regressions and was changed in 0.53.1 to
$ CC=clang CC_LD=lld meson <options>
$ CC=clang-cl CC_LD=link meson <options>
or in a cross or native file:
[binaries] c = 'clang' c_ld = 'lld'
There is a table of all environment variables supported Here
Set default C/C++ language version
project('myproj', 'c', 'cpp', default_options : ['c_std=c11', 'cpp_std=c++11'])
The language version can also be set on a per-target basis.
executable(..., override_options : ['c_std=c11'])
Lots of people seem to do this manually with
or something similar. Do not do that. It is not portable. Instead do
thread_dep = dependency('threads') executable(..., dependencies : thread_dep)
Set extra compiler and linker flags from the outside (when e.g. building distro packages)
The behavior is the same as with other build systems, with environment variables during first invocation. Do not use these when you need to rebuild the source
$ CFLAGS=-fsomething LDFLAGS=-Wl,--linker-flag meson <options>
Use an argument only with a specific compiler
First check which arguments to use.
if meson.get_compiler('c').get_id() == 'clang' extra_args = ['-fclang-flag'] else extra_args =  endif
Then use it in a target.
executable(..., c_args : extra_args)
If you want to use the arguments on all targets, then do this.
if meson.get_compiler('c').get_id() == 'clang' add_global_arguments('-fclang-flag', language : 'c') endif
Set a command's output to configuration
txt = run_command('script', 'argument', check: true).stdout().strip() cdata = configuration_data() cdata.set('SOMETHING', txt) configure_file(...)
Generate configuration data from files
The [fs module](#Fs-modules) offers theread
function which enables adding
the contents of arbitrary files to configuration data (among other uses):
fs = import('fs') cdata = configuration_data() copyright = fs.read('LICENSE') cdata.set('COPYRIGHT', copyright) if build_machine.system() == 'linux' os_release = fs.read('/etc/os-release') cdata.set('LINUX_BUILDER', os_release) endif configure_file(...)
Generate a runnable script with
configure_file preserves metadata so if your template file has
execute permissions, the generated file will have them too.
Producing a coverage report
First initialize the build directory with this command.
$ meson <other flags> -Db_coverage=true
Then issue the following commands.
$ meson compile $ meson test $ meson compile coverage-html (or coverage-xml)
The coverage report can be found in the meson-logs subdirectory.
New in 0.55.0 llvm-cov support for use with clang
Add some optimization to debug builds
By default the debug build does not use any optimizations. This is the
desired approach most of the time. However some projects benefit from
having some minor optimizations enabled. GCC even has a specific
-Og for this. To enable its use, just issue the
$ meson configure -Dc_args=-Og
This causes all subsequent builds to use this command line argument.
Use address sanitizer
Clang comes with a selection of analysis tools such as the address
has native support for these with the
$ meson <other options> -Db_sanitize=address
After this you just compile your code and run the test suite. Address sanitizer will abort executables which have bugs so they show up as test failures.
Use Clang static analyzer
Install scan-build program, then do this:
$ meson setup builddir $ ninja -C builddir scan-build
You can use the
SCANBUILD environment variable to choose the
$ SCANBUILD=<your exe> ninja -C builddir scan-build
You can use it for passing arguments to scan-build program by creating a script, for example:
#!/bin/sh scan-build -v --status-bugs "$@"
And then pass it through the variable (remember to use absolute path):
$ SCANBUILD=$(pwd)/my-scan-build.sh ninja -C builddir scan-build
Use profile guided optimization
Using profile guided optimization with GCC is a two phase operation. First we set up the project with profile measurements enabled and compile it.
$ meson setup <Meson options, such as --buildtype=debugoptimized> -Db_pgo=generate $ meson compile -C builddir
Then we need to run the program with some representative input. This step depends on your project.
Once that is done we change the compiler flags to use the generated information and rebuild.
$ meson configure -Db_pgo=use $ meson compile
After these steps the resulting binary is fully optimized.
Add math library (
Some platforms (e.g. Linux) have a standalone math library. Other
platforms (pretty much everyone else) do not. How to specify that
is used only when needed?
cc = meson.get_compiler('c') m_dep = cc.find_library('m', required : false) executable(..., dependencies : m_dep)
Install an executable to
executable(..., install : true, install_dir : get_option('libexecdir'))
Meson can use the CMake
find_package() ecosystem if CMake is
installed. To find a dependency with custom
cmake_module_path property to the path in your project where the
CMake scripts are stored.
Example for a
FindCmakeOnlyDep.cmake in a
cm_dep = dependency('CmakeOnlyDep', cmake_module_path : 'cmake')
cmake_module_path property is only needed for custom CMake scripts. System
wide CMake scripts are found automatically.
More information can be found here
Get a default not-found dependency?
null_dep = dependency('', required : false)
This can be used in cases where you want a default value, but might override it later.
# Not needed on Windows! my_dep = dependency('', required : false) if host_machine.system() in ['freebsd', 'netbsd', 'openbsd', 'dragonfly'] my_dep = dependency('some dep', required : false) elif host_machine.system() == 'linux' my_dep = dependency('some other dep', required : false) endif executable( 'myexe', my_sources, deps : [my_dep] )
The results of the search are