short-description: Built-in options to configure project properties ...
Meson provides two kinds of options: build options provided by the build files and built-in options that are either universal options, base options, compiler options.
A list of these options can be found by running meson --help. All these can be set by passing -Doption=value to meson (aka meson setup), or by setting them inside default_options of project() in your meson.build. Some options can also be set by --option=value, or --option value--- a list is shown by running meson setup --help.
For legacy reasons --warnlevel is the cli argument for the warning_level option.
They can also be edited after setup using meson configure -Doption=value.
Installation options are all relative to the prefix, except:
/usr: sysconfdir defaults to /etc, localstatedir defaults to /var, and sharedstatedir defaults to /var/lib/usr/local: localstatedir defaults to /var/local, and sharedstatedir defaults to /var/local/lib| Option | Default value | Description |
|---|---|---|
| prefix | see below | Installation prefix |
| bindir | bin | Executable directory |
| datadir | share | Data file directory |
| includedir | include | Header file directory |
| infodir | share/info | Info page directory |
| libdir | see below | Library directory |
| libexecdir | libexec | Library executable directory |
| localedir | share/locale | Locale data directory |
| localstatedir | var | Localstate data directory |
| mandir | share/man | Manual page directory |
| sbindir | sbin | System executable directory |
| sharedstatedir | com | Architecture-independent data directory |
| sysconfdir | etc | Sysconf data directory |
prefix defaults to C:/ on Windows, and /usr/local otherwise. You should always override this value.
libdir is automatically detected based on your platform, it should be correct when doing “native” (build machine == host machine) compilation. For cross compiles meson will try to guess the correct libdir, but it may not be accurate, especially on Linux where different distributions have different defaults. Using a cross file, particularly the paths section may be necessary.
Options that are labeled “per machine” in the table are set per machine. See the specifying options per machine section for details.
| Option | Default value | Description | Is per machine | Is per subproject |
|---|---|---|---|---|
| auto_features {enabled, disabled, auto} | auto | Override value of all ‘auto’ features | no | no |
| backend {ninja, vs, vs2010, vs2015, vs2017, vs2019, xcode} | ninja | Backend to use | no | no |
| buildtype {plain, debug, debugoptimized, release, minsize, custom} | debug | Build type to use | no | no |
| debug | true | Debug | no | no |
| default_library {shared, static, both} | shared | Default library type | no | yes |
| errorlogs | true | Whether to print the logs from failing tests. | no | no |
| install_umask {preserve, 0000-0777} | 022 | Default umask to apply on permissions of installed files | no | no |
| layout {mirror,flat} | mirror | Build directory layout | no | no |
| optimization {0, g, 1, 2, 3, s} | 0 | Optimization level | no | no |
| pkg_config_path {OS separated path} | '' | Additional paths for pkg-config to search before builtin paths | yes | no |
| cmake_prefix_path | [] | Additional prefixes for cmake to search before builtin paths | yes | no |
| stdsplit | true | Split stdout and stderr in test logs | no | no |
| strip | false | Strip targets on install | no | no |
| unity {on, off, subprojects} | off | Unity build | no | no |
| unity_size {>=2} | 4 | Unity file block size | no | no |
| warning_level {0, 1, 2, 3} | 1 | Set the warning level. From 0 = none to 3 = highest | no | yes |
| werror | false | Treat warnings as errors | no | yes |
| wrap_mode {default, nofallback, nodownload, forcefallback} | default | Wrap mode to use | no | no |
| force_fallback_for | [] | Force fallback for those dependencies | no | no |
For setting optimization levels and toggling debug, you can either set the buildtype option, or you can set the optimization and debug options which give finer control over the same. Whichever you decide to use, the other will be deduced from it. For example, -Dbuildtype=debugoptimized is the same as -Ddebug=true -Doptimization=2 and vice-versa. This table documents the two-way mapping:
| buildtype | debug | optimization |
|---|---|---|
| plain | false | 0 |
| debug | true | 0 |
| debugoptimized | true | 2 |
| release | false | 3 |
| minsize | true | s |
All other combinations of debug and optimization set buildtype to 'custom'.
These are set in the same way as universal options, either by -Doption=value, or by setting them inside default_options of project() in your meson.build. However, they cannot be shown in the output of meson --help because they depend on both the current platform and the compiler that will be selected. The only way to see them is to setup a builddir and then run meson configure on it with no options.
The following options are available. Note that they may not be available on all platforms or with all compilers:
| Option | Default value | Possible values | Description |
|---|---|---|---|
| b_asneeded | true | true, false | Use -Wl,--as-needed when linking |
| b_bitcode | false | true, false | Embed Apple bitcode, see below |
| b_colorout | always | auto, always, never | Use colored output |
| b_coverage | false | true, false | Enable coverage tracking |
| b_lundef | true | true, false | Don't allow undefined symbols when linking |
| b_lto | false | true, false | Use link time optimization |
| b_ndebug | false | true, false, if-release | Disable asserts |
| b_pch | true | true, false | Use precompiled headers |
| b_pgo | off | off, generate, use | Use profile guided optimization |
| b_sanitize | none | see below | Code sanitizer to use |
| b_staticpic | true | true, false | Build static libraries as position independent |
| b_pie | false | true, false | Build position-independent executables (since 0.49.0) |
| b_vscrt | from_buildtype | none, md, mdd, mt, mtd, from_buildtype | VS runtime library to use (since 0.48.0) |
The value of b_sanitize can be one of: none, address, thread, undefined, memory, address,undefined.
The default value of b_vscrt is from_buildtype. In that case, the following table is used internally to pick the CRT compiler arguments based on the value of the buildtype option:
| buildtype | Visual Studio CRT |
|---|---|
| debug | /MDd |
| debugoptimized | /MD |
| release | /MD |
| minsize | /MD |
| custom | error! |
b_bitcode will pass -fembed-bitcode while compiling and will pass -Wl,-bitcode_bundle while linking. These options are incompatible with b_asneeded, so that option will be silently disabled.
Shared modules will not have bitcode embedded because -Wl,-bitcode_bundle is incompatible with both -bundle and -Wl,-undefined,dynamic_lookup which are necessary for shared modules to work.
Same caveats as base options above.
The following options are available. They can be set by passing -Doption=value to meson. Note that both the options themselves and the possible values they can take will depend on the target platform or compiler being used:
| Option | Default value | Possible values | Description |
|---|---|---|---|
| c_args | free-form comma-separated list | C compile arguments to use | |
| c_link_args | free-form comma-separated list | C link arguments to use | |
| c_std | none | none, c89, c99, c11, c17, c18, c2x, gnu89, gnu99, gnu11, gnu17, gnu18, gnu2x | C language standard to use |
| c_winlibs | see below | free-form comma-separated list | Standard Windows libs to link against |
| c_thread_count | 4 | integer value ≥ 0 | Number of threads to use with emcc when using threads |
| cpp_args | free-form comma-separated list | C++ compile arguments to use | |
| cpp_link_args | free-form comma-separated list | C++ link arguments to use | |
| cpp_std | none | none, c++98, c++03, c++11, c++14, c++17, c++2a c++1z, gnu++03, gnu++11, gnu++14, gnu++17, gnu++1z, gnu++2a, vc++14, vc++17, vc++latest | C++ language standard to use |
| cpp_debugstl | false | true, false | C++ STL debug mode |
| cpp_eh | default | none, default, a, s, sc | C++ exception handling type |
| cpp_rtti | true | true, false | Whether to enable RTTI (runtime type identification) |
| cpp_thread_count | 4 | integer value ≥ 0 | Number of threads to use with emcc when using threads |
| cpp_winlibs | see below | free-form comma-separated list | Standard Windows libs to link against |
| fortran_std | none | [none, legacy, f95, f2003, f2008, f2018] | Fortran language standard to use |
The default values of c_winlibs and cpp_winlibs are in compiler-specific argument forms, but the libraries are: kernel32, user32, gdi32, winspool, shell32, ole32, oleaut32, uuid, comdlg32, advapi32.
All these <lang>_* options are specified per machine. See below in the specifying options per machine section on how to do this in cross builds.
When using MSVC, cpp_eh=none will result in no exception flags being passed, while the cpp_eh=[value] will result in /EH[value]. Since 0.51.0 cpp_eh=default will result in /EHsc on MSVC. When using gcc-style compilers, nothing is passed (allowing exceptions to work), while cpp_eh=none passes -fno-exceptions.
Since 0.54.0 The <lang>_thread_count option can be used to control the value passed to -s PTHREAD_POOL_SIZE when using emcc. No other c/c++ compiler supports this option.
Since 0.51.0, some options are specified per machine rather than globally for all machine configurations. Prefixing the option with build. just affects the build machine configuration, while unprefixed just affects the host machine configuration, respectively. For example:
build.pkg_config_path controls the paths pkg-config will search for just native: true dependencies (build machine).
pkg_config_path controls the paths pkg-config will search for just native: false dependencies (host machine).
This is useful for cross builds. In the native builds, build = host, and the unprefixed option alone will suffice.
Prior to 0.51.0, these options just effected native builds when specified on the command line, as there was no build. prefix. Similarly named fields in the [properties] section of the cross file would effect cross compilers, but the code paths were fairly different allowing differences in behavior to crop out.
Since 0.54.0 default_library and werror built-in options can be defined per subproject. This is useful for example when building shared libraries in the main project, but static link a subproject, or when the main project must build with no warnings but some subprojects cannot.
Most of the time this would be used either by the parent project by setting subproject's default_options (e.g. subproject('foo', default_options: 'default_library=static')), or by the user using the command line -Dfoo:default_library=static.
The value is overriden in this order:
Since 0.56.0 warning_level can also be defined per subproject.