New features

Unescaped variables in pkgconfig files

Spaces in variable values are escaped with \, this is required in the case the value is a path that and is used in cflags or libs arguments. This was an undocumented behaviour that caused issues in the case the variable is a space separated list of items.

For backward compatibility reasons this behaviour could not be changed, new keyword arguments have thus been added: unescaped_variables and unescaped_uninstalled_variables.

pkg = import('pkgconfig')
...
pkg.generate(lib,
  variables: {
    'mypath': '/path/with spaces/are/escaped',
  },
  unescaped_variables: {
    'mylist': 'Hello World Is Not Escaped',
  },
)

The custom_target() function now accepts a feed argument

It is now possible to provide a feed: true argument to custom_target() to pipe the target's input file to the program's standard input.

Separate functions for qt preprocess

qt.preprocess is a large, complicated function that does a lot of things, a new set of compile_* functions have been provided as well. These are conceptually simpler, as they do a single thing.

Cython as as first class language

Meson now supports Cython as a first class language. This means you can write:

project('my project', 'cython')

py = import('python').find_installation()
dep_py = py.dependency()

py.extension_module(
    'foo',
    'foo.pyx',
    dependencies : dep_py,
)

And avoid the step through a generator that was previously required.

Support for the Wine Resource Compiler

Users can now choose wrc as the windres binary in their cross files and windows.compile_resources will handle it correctly. Together with winegcc patches in Wine 6.12 this enables basic support for compiling projects as a winelib by specifying winegcc/wineg++ as the compiler and wrc as the resource compiler in a cross file.

New vs2012 and vs2013 backend options

Adds the ability to generate Visual Studio 2012 and 2013 projects. This is an extension to the existing Visual Studio 2010 projects so that it is no longer required to manually upgrade the generated Visual Studio 2010 projects.

Generating Visual Studio 2010 projects has also been fixed since its developer command prompt does not provide a %VisualStudioVersion% envvar.

Developer environment

Expand the support for the link_whole: project option for pre-Visual Studio 2015 Update 2, where previously Visual Studio 2015 Update 2 or later was required for this, for the Ninja backend as well as the vs2010 (as well as the newly-added vs2012 and vs2013 backends).

Fs Module now accepts files objects

It is now possible to define a files() object and run most Fs module functions on the file, rather than passing a string and hoping it is in the same directory.

Compiler argument checking for get_supported_arguments

The compiler method get_supported_arguments now supports a new keyword argument named checked that can be set to one of warn, require or off (defaults to off) to enforce argument checks.

New custom dependency for libintl

Meson can now find the library needed for translating messages via gettext. This works both on systems where libc provides gettext, such as GNU or musl, and on systems where the gettext project's standalone intl support library is required, such as macOS.

Rather than doing something such as:

intl_dep = dependency('', required: false)

if cc.has_function('ngettext')
  intl_found = true
else
  intl_dep = cc.find_library('intl', required: false)
  intl_found = intl_dep.found()
endif

if intl_found
  # build options that need gettext
  conf.set('ENABLE_NLS', 1)
endif

one may simply use:

intl_dep = dependency('intl', required: false)

if intl_dep.found()
  # build options that need gettext
  conf.set('ENABLE_NLS', 1)
endif

Parallelized meson subprojects commands

All meson subprojects commands are now run on each subproject in parallel by default. The number of processes can be controlled with --num-processes argument.

This speeds up considerably IO-bound operations such as downloads and git fetch.

Using Vala no longer requires C in the project languages

Meson will now add C automatically. Since the use of C is an implementation detail of Vala, Meson shouldn't require users to add it.

The import() function gains required and disabler arguments

In addition, modules now have a found() method, like programs and dependencies. This allows them to be conditionally required, and used in most places that an object with a found() method can be.

Objective C/C++ standard versions

Objective C and C++ compilations will from now on use the language versions set in c_std and cpp_std, respectively. It is not possible to set the language version separately for Objective C and plain C.

Qt.preprocess source arguments deprecated

The qt.preprocess method currently has this signature: qt.preprocess(name: str | None, *srcs: str), this is not a nice signature because it's confusing, and there's a sources keyword argument as well. Both of these pass sources through unmodified, this is a bit of a historical accident, and not the way that any other module works. These have been deprecated, so instead of:

sources = qt.preprocess(
    name,
    list, of, sources,
    sources : [more, sources],
    ... # things to process,
)

executable(
    'foo',
    sources,
)

use

processed = qt.preprocess(
    name,
    ... # thins to process
)

executable(
    'foo',
    'list', 'of', 'sources', 'more', 'sources', processed,
)

New build target methods

The build_tgt object now supports the following two functions, to ensure feature compatibility with external_program objects:

• found(): Always returns true. This function is meant to make executables objects feature compatible with external program objects. This simplifies use-cases where an executable is used instead of an external program.

• path(): (deprecated) does the exact same as full_path(). NOTE: This function is solely kept for compatibility with external program objects. It will be removed once the, also deprecated, corresponding path() function in the external program object is removed.

Automatically set up Visual Studio environment

When Meson is run on Windows it will automatically set up the environment to use Visual Studio if no other compiler toolchain can be detected. This means that you can run Meson commands from any command prompt or directly from any IDE. This sets up the 64 bit native environment. If you need any other, then you need to set it up manually as before.

gnome.compile_schemas() sets GSETTINGS_SCHEMA_DIR into devenv

When using gnome.compile_schemas() the location of the compiled schema is added to GSETTINGS_SCHEMA_DIR environment variable when using meson devenv command.

update_desktop_database added to gnome.post_install()

Applications that install a .desktop file containing a MimeType need to update the cache upon installation. Most applications do that using a custom script, but it can now be done by Meson directly.

See gnome.post_install().