docs/markdown/Running-Meson.md - meson - Git at Google

 ---
 short-description: Building a project with Meson
 ...

 # Running Meson

 There are two different ways of invoking Meson. First, you can run it
 directly from the source tree with the command
 `/path/to/source/meson.py`. Meson may also be installed in which case
 the command is simply `meson`. In this manual we only use the latter
 format for simplicity.

 At the time of writing only a command line version of Meson is
 available. This means that Meson must be invoked using the
 terminal. If you wish to use the MSVC compiler, you need to run Meson
 under "Visual Studio command prompt".

 Configuring the source
 ==

 Let us assume that we have a source tree that has a Meson build
 system. This means that at the topmost directory has a file called
 `meson.build`. We run the following commands to get the build started.


     cd /path/to/source/root
     mkdir builddir
     cd builddir
     meson ..

 First we create a directory to hold all files generated during the
 build. Then we go into it and invoke Meson, giving it the location of
 the source root.

 Hint: The syntax of meson is `meson [options] [srcdir] [builddir]`,
 but you may omit either `srcdir` or `builddir`. Meson will deduce the
 `srcdir` by the location of `meson.build`. The other one will be your
 `pwd`.

 Meson then loads the build configuration file and writes the
 corresponding build backend in the build directory. By default Meson
 generates a *debug build*, which turns on basic warnings and debug
 information and disables compiler optimizations.

 You can specify a different type of build with the `--buildtype`
 command line argument. It can have one of the following values.

 | value            | meaning                                                                                                                                                    |
 | ------           | --------                                                                                                                                                   |
 | `plain`          | no extra build flags are used, even for compiler warnings, useful for distro packagers and other cases where you need to specify all arguments by yourself |
 | `debug`          | debug info is generated but the result is not optimized, this is the default                                                                               |
 | `debugoptimized` | debug info is generated and the code is optimized (on most compilers this means `-g -O2`)                                                                  |
 | `release`        | full optimization, no debug info                                                                                                                           |

 The build directory is mandatory. The reason for this is that it
 simplifies the build process immensely. Meson will not under any
 circumstances write files inside the source directory (if it does, it
 is a bug and should be fixed). This means that the user does not need
 to add a bunch of files to their revision control's ignore list. It
 also means that you can create arbitrarily many build directories for
 any given source tree. If we wanted to test building the source code
 with the Clang compiler instead of the system default, we could just
 type the following commands.

     cd /path/to/source/root
     mkdir buildclang
     cd buildclang
     CC=clang CXX=clang++ meson ..

 This separation is even more powerful if your code has multiple
 configuration options (such as multiple data backends). You can create
 a separate subdirectory for each of them. You can also have build
 directories for optimized builds, code coverage, static analysis and
 so on. They are all neatly separated and use the same source
 tree. Changing between different configurations is just a question of
 changing to the corresponding directory.

 Unless otherwise mentioned, all following command line invocations are
 meant to be run in the build directory.

 By default Meson will use the Ninja backend to build your project. If
 you wish to use any of the other backends, you need to pass the
 corresponding argument during configuration time. As an example, here
 is how you would use Meson to generate a Visual studio solution.

     meson <source dir> <build dir> --backend=vs2010

 You can then open the generated solution with Visual Studio and
 compile it in the usual way. A list of backends can be obtained with
 `meson --help`.

 Building the source
 ==

 If you are not using an IDE, Meson uses the [Ninja build
 system](https://ninja-build.org/) to actually build the code. To start
 the build, simply type the following command.

     ninja

 The main usability difference between Ninja and Make is that Ninja
 will automatically detect the number of CPUs in your computer and
 parallelize itself accordingly. You can override the amount of
 parallel processes used with the command line argument `-j <num
 processes>`.

 It should be noted that after the initial configure step `ninja` is
 the only command you ever need to type to compile. No matter how you
 alter your source tree (short of moving it to a completely new
 location), Meson will detect the changes and regenerate itself
 accordingly. This is especially handy if you have multiple build
 directories. Often one of them is used for development (the "debug"
 build) and others only every now and then (such as a "static analysis"
 build). Any configuration can be built just by `cd`'ing to the
 corresponding directory and running Ninja.

 Running tests
 ==

 Meson provides native support for running tests. The command to do
 that is simple.

     ninja test

 Meson does not force the use of any particular testing framework. You
 are free to use GTest, Boost Test, Check or even custom executables.

 Installing
 ==

 Installing the built software is just as simple.

     ninja install

 By default Meson installs to `/usr/local`. This can be changed by
 passing the command line argument `--prefix /your/prefix` to Meson
 during configure time. Meson also supports the `DESTDIR` variable used
 in e.g. building packages. It is used like this:

     DESTDIR=/path/to/staging ninja install

 Command line help
 ==

 Meson has a standard command line help feature. It can be accessed
 with the following command.

     meson --help
	---
	short-description: Building a project with Meson
	...

	# Running Meson

	There are two different ways of invoking Meson. First, you can run it
	directly from the source tree with the command
	`/path/to/source/meson.py`. Meson may also be installed in which case
	the command is simply `meson`. In this manual we only use the latter
	format for simplicity.

	At the time of writing only a command line version of Meson is
	available. This means that Meson must be invoked using the
	terminal. If you wish to use the MSVC compiler, you need to run Meson
	under "Visual Studio command prompt".

	Configuring the source
	==

	Let us assume that we have a source tree that has a Meson build
	system. This means that at the topmost directory has a file called
	`meson.build`. We run the following commands to get the build started.


	cd /path/to/source/root
	mkdir builddir
	cd builddir
	meson ..

	First we create a directory to hold all files generated during the
	build. Then we go into it and invoke Meson, giving it the location of
	the source root.

	Hint: The syntax of meson is `meson [options] [srcdir] [builddir]`,
	but you may omit either `srcdir` or `builddir`. Meson will deduce the
	`srcdir` by the location of `meson.build`. The other one will be your
	`pwd`.

	Meson then loads the build configuration file and writes the
	corresponding build backend in the build directory. By default Meson
	generates a debug build, which turns on basic warnings and debug
	information and disables compiler optimizations.

	You can specify a different type of build with the `--buildtype`
	command line argument. It can have one of the following values.

	\| value \| meaning \|
	\| ------ \| -------- \|
	\| `plain` \| no extra build flags are used, even for compiler warnings, useful for distro packagers and other cases where you need to specify all arguments by yourself \|
	\| `debug` \| debug info is generated but the result is not optimized, this is the default \|
	\| `debugoptimized` \| debug info is generated and the code is optimized (on most compilers this means `-g -O2`) \|
	\| `release` \| full optimization, no debug info \|

	The build directory is mandatory. The reason for this is that it
	simplifies the build process immensely. Meson will not under any
	circumstances write files inside the source directory (if it does, it
	is a bug and should be fixed). This means that the user does not need
	to add a bunch of files to their revision control's ignore list. It
	also means that you can create arbitrarily many build directories for
	any given source tree. If we wanted to test building the source code
	with the Clang compiler instead of the system default, we could just
	type the following commands.

	cd /path/to/source/root
	mkdir buildclang
	cd buildclang
	CC=clang CXX=clang++ meson ..

	This separation is even more powerful if your code has multiple
	configuration options (such as multiple data backends). You can create
	a separate subdirectory for each of them. You can also have build
	directories for optimized builds, code coverage, static analysis and
	so on. They are all neatly separated and use the same source
	tree. Changing between different configurations is just a question of
	changing to the corresponding directory.

	Unless otherwise mentioned, all following command line invocations are
	meant to be run in the build directory.

	By default Meson will use the Ninja backend to build your project. If
	you wish to use any of the other backends, you need to pass the
	corresponding argument during configuration time. As an example, here
	is how you would use Meson to generate a Visual studio solution.

	meson <source dir> <build dir> --backend=vs2010

	You can then open the generated solution with Visual Studio and
	compile it in the usual way. A list of backends can be obtained with
	`meson --help`.

	Building the source
	==

	If you are not using an IDE, Meson uses the [Ninja build
	system](https://ninja-build.org/) to actually build the code. To start
	the build, simply type the following command.

	ninja

	The main usability difference between Ninja and Make is that Ninja
	will automatically detect the number of CPUs in your computer and
	parallelize itself accordingly. You can override the amount of
	parallel processes used with the command line argument `-j <num
	processes>`.

	It should be noted that after the initial configure step `ninja` is
	the only command you ever need to type to compile. No matter how you
	alter your source tree (short of moving it to a completely new
	location), Meson will detect the changes and regenerate itself
	accordingly. This is especially handy if you have multiple build
	directories. Often one of them is used for development (the "debug"
	build) and others only every now and then (such as a "static analysis"
	build). Any configuration can be built just by `cd`'ing to the
	corresponding directory and running Ninja.

	Running tests
	==

	Meson provides native support for running tests. The command to do
	that is simple.

	ninja test

	Meson does not force the use of any particular testing framework. You
	are free to use GTest, Boost Test, Check or even custom executables.

	Installing
	==

	Installing the built software is just as simple.

	ninja install

	By default Meson installs to `/usr/local`. This can be changed by
	passing the command line argument `--prefix /your/prefix` to Meson
	during configure time. Meson also supports the `DESTDIR` variable used
	in e.g. building packages. It is used like this:

	DESTDIR=/path/to/staging ninja install

	Command line help
	==

	Meson has a standard command line help feature. It can be accessed
	with the following command.

	meson --help