The initiative to move to Meson has been mostly completed; the list of ported modules is now out of date. This page is maintained mostly for historical/archival reasons.

GNOME Goal: Port modules to use Meson build system

As the meson webpage says:

Meson is an open source build system meant to be both extremely fast, and, even more importantly, as user friendly as possible.

The main design point of Meson is that every moment a developer spends writing or debugging build definitions is a second wasted. So is every second spent waiting for the build system to actually start compiling code.

This GNOMEGoal is to coordinate efforts and avoid duplicating work

Guidelines

Meson documentation is quite complete, take a look to these links:

• http://mesonbuild.com/Porting-from-autotools.html

• http://mesonbuild.com/Manual.html

Things to check while porting

• If your project has configuration options for the Autotools build make sure to port them all to the Meson one, following these style guidelines

  • Drop the enable from --enable-foo boolean options; Meson has boolean values, so -Denable-foo=true would read as redundant, and -Denable-foo=false would read as contradictory. Use -Dfoo=true or -Dfoo=false instead

  • Similarly, you should drop with from --with-bar options

  • Use a consistent separator character for multi-word options, preferably the underscore _, like cert_file or cups_print_backend

  • Try to avoid automatic feature detection; this makes it harder for distributors and continuous integration systems to identify the dependencies needed to build your project.

    • Note that this is not a Meson requirement, but is important for consistent behaviour across GNOME modules

    • Auto features are now OK to use in GNOME due to the addition of the -Dauto_features=enabled functionality in meson 0.47, which allows auto feature detection to be disabled.

  • Do not add "enable debug" options to inject pre-processor symbols into the build, or control the presence of debugging messages; you should use Meson's own buildtype option

    • If you have a ENABLE_DEBUG symbol, you should set it for debug and/or debugoptimized build types

    • For release build types you probably want to add -DG_DISABLE_CAST_CHECKS to your project's arguments

    • It's not recommended to add -DG_DISABLE_CHECKS in any kind of build; for specialized builds (such as embedded environments, or other resource-constrained environments), you should use the plain build type in Meson, and inject your own CFLAGS

  • Do not add "enable -Werror" options to make warnings fail the build; you should use Meson's own --werror build option

  • Typical options mapping for GNOME modules

    • --enable-gtk-doc = gtk_doc

    • --enable-man = man

    • --enable-introspection = introspection

Things to check after the porting:

• If you port a library:

  • Make sure the list of exported symbols is the same between Autotools and Meson builds (may want gnu_symbol_visibility: 'hidden')

  • Make sure you maintain compatible sonames (use version and soversion when building a library() target)

  • Make sure you install all the needed headers, if applicable
  • Make sure you install all the pkg-config files
• Ensure that consumers of your project can use it as a sub-project in their own Meson builds

  • Never use the source_root() and build_root() of the meson object to create paths

  • Make sure that any internal dependency object created using declare_dependency() depends on the generated headers and introspection files

• If you release a tarball using Autotools, remember to include the Meson files on it

  • Use the EXTRA_DIST Automake target to include the meson.build, meson_options.txt, and ancillary scripts you may use

• Update jhbuild, gnome-build-meta and gnome-continuous to use Meson

  • Beware that Continuous will automatically choose Meson over Autotools if not specified, so you should add { "force-autotools": true } before landing the meson branch (or make sure you change the configuration asap to minimize the breakage)

  • Make sure you do this before removing the Autotools build!

• Use meld to diff install directories of the projects

• If you rely on symbol visibility — e.g. using libtool or using pre-processor macros — use nm to check that you're still exporting the same ABI, also abidiff from abigail can be your good friend

Comments before approval

Status of this goal

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