Meson (software)

The syntax of Meson's build description files, the Meson language, borrows from Python, but is not Python. It is designed such that it can be reimplemented in any other language; for example, muon{{Cite web |title=muon.build |url=https://muon.build/ |access-date=2023-01-27}} is a C implementation, and Meson++{{Cite web |last=Baker |first=Dylan |title=dcbaker/meson-plus-plus |website=GitHub |date=2021-05-28 |url=https://github.com/dcbaker/meson-plus-plus |access-date=2021-05-28}} is a C++ implementation. The dependency on Python is an implementation detail.

The Meson language is intentionally not Turing-complete, and can therefore not express an arbitrary program. Instead, arbitrary build steps beyond compiling supported languages can be represented as custom targets.

The Meson language is strongly typed, such that builtin types like library, executable, string, and lists thereof, are non-interchangeable. In particular, unlike Make, the list type does not split strings on whitespace. Thus, whitespace and other characters in filenames and program arguments are handled cleanly.

As with any typical buildsystem, correct incremental builds are the most significant speed feature (because all incremental progress is discarded whenever the user is forced to do a clean build).

Unlike bare Make, the separate configure step ensures that changes to arguments, environment variables and command output are not partially applied in subsequent builds, which would lead to a stale build.

Like Ninja, Meson does not support globbing of source files. By requiring all source files to be listed in the build definition files, the build definition file timestamps are sufficient to determine whether the set of source files has changed, thereby ensuring that removed source files are detected. CMake supports globbing, but recommends against it for the same reason.

Meson uses ccache automatically if installed.{{cite web |title=Feature Autodetection |url=https://mesonbuild.com/Feature-autodetection.html}} It also detects changes to symbol tables of shared libraries to skip relinking executables against the library when there are no ABI changes. Precompiled headers are supported, but require configuration.{{cite web |title=Precompiled headers |url=https://mesonbuild.com/Precompiled-headers.html}} Debug builds are without optimization by default.

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A stated goal of Meson is to facilitate modern development practices. As such, Meson knows how to do unity builds,{{cite web |title=Unity builds |url=https://mesonbuild.com/Unity-builds.html}} build with test coverage{{cite web |title=Unit-tests |url=https://mesonbuild.com/Unit-tests.html#coverage}} etc. without the programmer having to write support for this.

Meson can automatically find and use external dependencies installed on the user's system via pkg-config, CMake, and project-specific lookups.{{Cite web|url=https://mesonbuild.com/Dependencies.html#dependencies-with-custom-lookup-functionality|title=Dependencies with custom lookup functionality — Meson documentation}}

Alternatively, or as a fallback, a dependency can be provided as a subproject – a Meson project within another, either contained or as a download link, possibly with patches. This lets Meson resolve dependency hell for the convenience of casual users who want to compile the project, but may contribute to software bloat if a common installed dependency could have been used instead. The mode favored by Linux packagers is therefore fallback.

Meson supports Meson and CMake subprojects. A Meson build file may also refer to the WrapDB service.

Cross compilation requires extra configuration, which Meson supports in the form of a separate cross file, which can be external to the Meson project.

Setting the library installation directory on x86_64 Unix is handled automatically by Meson, but not by other tools such as Autotools.{{clarify|date=February 2025}}

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GNOME has made it a goal to port its projects to Meson.{{cite web |url=https://wiki.gnome.org/Initiatives/GnomeGoals/MesonPorting |title=GNOME Goal: Port modules to use Meson build system}} As of late 2017, GNOME Shell itself exclusively requires Meson after abandoning Autotools,{{cite web |url=https://www.phoronix.com/scan.php?page=news_item&px=GNOME-3.26-Beta |title=GNOME 3.26 Beta Debuts: More Meson Porting, Wayland Action}} and central components like GTK+, Clutter-GTK, GLib and GStreamer can be built with Meson.

Many freedesktop.org projects have switched to Meson. Systemd relies on Meson since dropping Autotools in version 234,{{cite web |url=https://github.com/systemd/systemd/pull/6266 |title=Drop support for autotools| website=GitHub }} and also X.Org{{cite web |url=https://www.phoronix.com/scan.php?page=news_item&px=Mesa-X-Server-Lands |title=Meson Support Has Landed In The X.Org Server

}} and Mesa{{cite web |url=https://www.phoronix.com/scan.php?page=news_item&px=Mesa-Closer-To-Kill-Autotools |title=Mesa Developers Move Closer To Dropping Autotools Build System In Favor Of Meson}} were ported to Meson.

Feature comparison with CMake and Make.

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{{Reflist|30em|refs=

{{cite web|url=http://mesonbuild.com/Syntax.html|title=Meson Syntax}}

{{cite web|url=http://mesonbuild.com/FAQ.html|title=Meson Frequently Asked Questions}}

{{cite web|url=https://cmake.org/cmake/help/v3.2/command/file.html|title=CMake FILE command|quote=Note: We do not recommend using GLOB to collect a list of source files from your source tree. If no CMakeLists.txt file changes when a source is added or removed, the generated build system cannot know when to ask CMake to regenerate.}}

{{cite web|url=https://build.opensuse.org/package/show/openSUSE:Factory/meson|quote=Meson aims to optimize programmer productivity by providing simple, out-of-the-box support for modern software development tools and practices, such as unit tests, coverage reports, Valgrind, CCache and the like.|title=High productivity build system|date=30 January 2025 }}

{{cite web|url=http://mesonbuild.com/Wrap-dependency-system-manual.html|title=Wrap dependency system manual}}

{{cite web|url=http://mesonbuild.com/Cross-compilation.html|title=Cross compilation}}

{{cite web|url=https://blogs.gnome.org/ignatenko/2015/05/21/meson-and-3rd-party-dependencies-only-one-correct-way/|title=Meson and 3rd party dependencies. Only one correct way}}

{{cite web|url=https://gitlab.kitware.com/cmake/cmake/issues/1260|title=CMake support for precompiled headers|accessdate=13 March 2018}}

{{cite web|url=https://www.microsoft.com/en-us/research/wp-content/uploads/2016/03/hadrian.pdf|title=Non-recursive Make Considered Harmful| website=Microsoft |quote=Recursive Make is considered harmful for very good reasons (Miller 1998); it is not possible to accurately track dependencies when the build system is constructed of separate components that invoke each other.}}

{{cite web |title=Make test does not depend on make all |url=https://gitlab.kitware.com/cmake/cmake/-/issues/8774 |website=Kitware issue tracker |accessdate=3 September 2020 |date=2016-06-23}}

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Category:Build automation

Category:Compiling tools

Category:Free software programmed in Python

Category:Meson build system

Category:Software using the Apache license