| --- |
| short-description: Built-in options to configure project properties |
| ... |
| |
| # Built-in options |
| |
| Meson provides two kinds of options: [build options provided by the |
| build files](Build-options.md) and built-in options that are either |
| universal options, base options, compiler options. |
| |
| ## Universal options |
| |
| 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 usually relative to the prefix but it should |
| not be relied on, since they can be absolute paths in the following cases: |
| |
| * When the prefix is `/usr`: `sysconfdir` defaults to `/etc`, |
| `localstatedir` defaults to `/var`, and `sharedstatedir` defaults to |
| `/var/lib` |
| * When the prefix is `/usr/local`: `localstatedir` defaults |
| to `/var/local`, and `sharedstatedir` defaults to `/var/local/lib` |
| * When an absolute path outside of prefix is provided by the user/distributor. |
| |
| ### Directories |
| |
| | 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 | |
| | licensedir | see below | Licenses directory (since 1.1.0)| |
| | 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](Cross-compilation.md#defining-the-environment), particularly the |
| paths section may be necessary. |
| |
| `licensedir` is empty by default. If set, it defines the default location |
| to install a dependency manifest and project licenses. For more details, |
| see [[meson.install_dependency_manifest]]. |
| |
| ### Core options |
| |
| Options that are labeled "per machine" in the table are set per |
| machine. See the [specifying options per |
| machine](#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,<br>vs2010, vs2012, vs2013, vs2015, vs2017, vs2019, vs2022, xcode, none} | ninja | Backend to use | no | no | |
| | buildtype {plain, debug,<br>debugoptimized, release, minsize, custom} | debug | Build type to use | no | no | |
| | debug | true | Enable debug symbols and other information | 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 {plain, 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 | |
| | prefer_static | false | Whether to try static linking before shared linking | no | 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, everything} | 1 | Set the warning level. From 0 = none to everything = highest | no | yes | |
| | werror | false | Treat warnings as errors | no | yes | |
| | wrap_mode {default, nofallback,<br>nodownload, forcefallback, nopromote} | default | Wrap mode to use | no | no | |
| | force_fallback_for | [] | Force fallback for those dependencies | no | no | |
| | vsenv | false | Activate Visual Studio environment | no | no | |
| |
| #### Details for `backend` |
| |
| Several build file formats are supported as command runners to build the |
| configured project. Meson prefers ninja by default, but platform-specific |
| backends are also available for better IDE integration with native tooling: |
| Visual Studio for Windows, and xcode for macOS. It is also possible to |
| configure with no backend at all, which is an error if you have targets to |
| build, but for projects that need configuration + testing + installation allows |
| for a lighter automated build pipeline. |
| |
| #### Details for `buildtype` |
| |
| <a name="build-type-options"></a> 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 | plain | |
| | debug | true | 0 | |
| | debugoptimized | true | 2 | |
| | release | false | 3 | |
| | minsize | true | s | |
| |
| All other combinations of `debug` and `optimization` set `buildtype` to `'custom'`. |
| |
| #### Details for `warning_level` |
| |
| Exact flags per warning level is compiler specific, but there is an approximative |
| table for most common compilers. |
| |
| | Warning level | GCC/Clang | MSVC | |
| | ------------- | --- | ---- | |
| | 0 | | | |
| | 1 | -Wall | /W2 | |
| | 2 | -Wall -Wextra | /W3 | |
| | 3 | -Wall -Wextra -Wpedantic | /W4 | |
| | everything | -Weverything | /Wall | |
| |
| Clang's `-Weverything` is emulated on GCC by passing all known warning flags. |
| |
| #### Details for `vsenv` |
| |
| The `--vsenv` argument is supported since `0.60.0`, `-Dvsenv=true` syntax is supported |
| since `1.1.0`. |
| |
| Since `0.59.0`, meson automatically activates a Visual Studio environment on Windows |
| for all its subcommands, but only if no other compilers (e.g. `gcc` or `clang`) |
| are found, and silently continues if Visual Studio activation fails. |
| |
| Setting the `vsenv` option to `true` forces Visual Studio activation even when other |
| compilers are found. It also make Meson abort with an error message when activation |
| fails. |
| |
| `vsenv` is `true` by default when using the `vs` backend. |
| |
| ## Base options |
| |
| 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 setup --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_lto_threads | 0 | Any integer* | Use multiple threads for lto. *(Added in 0.57.0)* | |
| | b_lto_mode | default | default, thin | Select between lto modes, thin and default. *(Added in 0.57.0)* | |
| | b_thinlto_cache | false | true, false | Enable LLVM's ThinLTO cache for faster incremental builds. *(Added in 0.64.0)* | |
| | b_thinlto_cache_dir | (Internal build dir) | true, false | Specify where to store ThinLTO cache objects. *(Added in 0.64.0)* | |
| | 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, static_from_buildtype | VS runtime library to use (since 0.48.0) (static_from_buildtype since 0.56.0) | |
| |
| The value of `b_sanitize` can be one of: `none`, `address`, `thread`, |
| `undefined`, `memory`, `leak`, `address,undefined`, but note that some |
| compilers might not support all of them. For example Visual Studio |
| only supports the address sanitizer. |
| |
| \* < 0 means disable, == 0 means automatic selection, > 0 sets a specific number to use |
| |
| LLVM supports `thin` lto, for more discussion see [LLVM's documentation](https://clang.llvm.org/docs/ThinLTO.html) |
| |
| <a name="b_vscrt-from_buildtype"></a> |
| The default value of `b_vscrt` is `from_buildtype`. The following table is |
| used internally to pick the CRT compiler arguments for `from_buildtype` or |
| `static_from_buildtype` *(since 0.56)* based on the value of the `buildtype` |
| option: |
| |
| | buildtype | from_buildtype | static_from_buildtype | |
| | -------- | -------------- | --------------------- | |
| | debug | `/MDd` | `/MTd` | |
| | debugoptimized | `/MD` | `/MT` | |
| | release | `/MD` | `/MT` | |
| | minsize | `/MD` | `/MT` | |
| | custom | error! | error! | |
| |
| ### Notes about Apple Bitcode support |
| |
| `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_module]]s 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. |
| |
| ## Compiler options |
| |
| 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++20 <br/>c++2a, c++1z, gnu++03, gnu++11, gnu++14, gnu++17, gnu++1z, <br/> gnu++2a, gnu++20, 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 | |
| | cuda_ccbindir | | filesystem path | CUDA non-default toolchain directory to use (-ccbin) *(Added in 0.57.1)* | |
| |
| 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](#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 *0.63.0* all compiler options can be set per subproject, see |
| [here](#specifying-options-per-subproject) for details on how the default value |
| is inherited from the main project. This is useful, for example, when the main |
| project requires C++11, but a subproject requires C++14. The `cpp_std` value |
| from the subproject's `default_options` is now respected. |
| |
| ## Specifying options per machine |
| |
| Since *0.51.0*, some options are specified per machine rather than |
| globally for all machine configurations. Prefixing the option with |
| `build.` only affects the build machine configuration, while leaving it |
| unprefixed only affects the host machine configuration. |
| For example: |
| |
| - `build.pkg_config_path` controls the paths pkg-config will search |
| for `native: true` (build machine) dependencies. |
| |
| - `pkg_config_path` controls the paths pkg-config will search for |
| `native: false` (host machine) dependencies. |
| |
| This is useful for cross builds. In native builds, the build and host |
| machines are the same, and the unprefixed option alone will suffice. |
| |
| Prior to *0.51.0*, these options only affected 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 affect cross compilers, but the code paths were fairly different, |
| allowing differences in behavior to crop out. |
| |
| ## Specifying options per subproject |
| |
| 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 and statically linking 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 in the parent project by |
| setting subproject's default_options (e.g. `subproject('foo', |
| default_options: 'default_library=static')`), or by the user through the |
| command line: `-Dfoo:default_library=static`. |
| |
| The value is overridden in this order: |
| - Value from parent project |
| - Value from subproject's default_options if set |
| - Value from subproject() default_options if set |
| - Value from command line if set |
| |
| Since *0.56.0* `warning_level` can also be defined per subproject. |
| |
| ## Module options |
| |
| Some Meson modules have built-in options. They can be set by prefixing the |
| option with the module's name: |
| `-D<module>.<option>=<value>` (e.g. `-Dpython.platlibdir=/foo`). |
| |
| ### Pkgconfig module |
| |
| | Option | Default value | Possible values | Description | |
| |-------------|---------------|-----------------|------------------------------------------------------------| |
| | relocatable | false | true, false | Generate the pkgconfig files as relocatable (Since 0.63.0) | |
| |
| *Since 0.63.0* The `pkgconfig.relocatable` option is used by the |
| pkgconfig module–namely [`pkg.generate()`](Pkgconfig-module.md)–and |
| affects how the `prefix` (not to be confused with the |
| [install prefix](#directories)) in the generated pkgconfig file is set. |
| When it is `true`, the `prefix` will be relative to the `install_dir`-this |
| allows the pkgconfig file to be moved around and still work, as long |
| as the relative path is not broken. In general, this allows for the whole |
| installed package to be placed anywhere on the system and still work as a |
| dependency. When it is set to `false`, the `prefix` will be the same as |
| the install prefix. |
| |
| An error will be raised if `pkgconfig.relocatable` is `true` and the |
| `install_dir` for a generated pkgconfig file points outside the |
| install prefix. For example: if the install prefix is `/usr` and the |
| `install_dir` for a pkgconfig file is `/var/lib/pkgconfig`. |
| |
| ### Python module |
| |
| | Option | Default value | Possible values | Description | |
| | ------ | ------------- | ----------------- | ----------- | |
| | install_env | prefix | {auto,prefix,system,venv} | Which python environment to install to (Since 0.62.0) | |
| | platlibdir | | Directory path | Directory for site-specific, platform-specific files (Since 0.60.0) | |
| | purelibdir | | Directory path | Directory for site-specific, non-platform-specific files (Since 0.60.0) | |
| |
| *Since 0.60.0* The `python.platlibdir` and `python.purelibdir` options are used |
| by the python module methods `python.install_sources()` and |
| `python.get_install_dir()`; Meson tries to detect the correct installation paths |
| and make them relative to the installation `prefix` by default which will often |
| result in the interpreter not finding the installed python modules unless |
| `prefix` is `/usr` on Linux, or, for instance, `C:\Python39` on Windows. These |
| options can be absolute paths outside of `prefix`. |
| |
| *Since 0.62.0* The `python.install_env` option is used to detect the correct |
| installation path. Setting to `system` will avoid making the paths relative to |
| `prefix` and instead use the global site-packages of the selected python |
| interpreter directly, even if it is a venv. Setting to `venv` will instead use |
| the paths for the virtualenv the python found installation comes from (or fail |
| if it is not a virtualenv). Setting to `auto` will check if the found |
| installation is a virtualenv, and use `venv` or `system` as appropriate (but |
| never `prefix`). This option is mutually exclusive with the `platlibdir`/`purelibdir`. |
| |
| For backwards compatibility purposes, the default `install_env` is `prefix`. |
