New features

Libgcrypt dependency now supports libgcrypt-config

Earlier, dependency('libgcrypt') could only detect the library with pkg-config files. Now, if pkg-config files are not found, Meson will look for libgcrypt-config and if it's found, will use that to find the library.

New `section` key for the buildoptions introspection

Meson now has a new section key in each build option. This allows IDEs to group these options similar to meson configure.

The possible values for section are:

core
backend
base
compiler
directory
user
test

CC-RX compiler for C and CPP

Cross-compilation is now supported for Renesas RX targets with the CC-RX compiler.

The environment path should be set properly for the CC-RX compiler executables. The -cpu option with the appropriate value should be mentioned in the cross-file as shown in the snippet below.

[properties]
c_args      = ['-cpu=rx600']
cpp_args    = ['-cpu=rx600']

The default extension of the executable output is .abs. Other target specific arguments to the compiler and linker will need to be added explicitly from the cross-file(c_args/c_link_args/cpp_args/cpp_link_args) or some other way. Refer to the CC-RX User's manual for additional compiler and linker options.

CMake `find_package` dependency backend

Meson can now use the CMake find_package ecosystem to detect dependencies. Both the old-style <NAME>_LIBRARIES variables as well as imported targets are supported. Meson can automatically guess the correct CMake target in most cases but it is also possible to manually specify a target with the modules property.

# Implicitly uses CMake as a fallback and guesses a target
dep1 = dependency('KF5TextEditor')

# Manually specify one or more CMake targets to use
dep2 = dependency('ZLIB', method : 'cmake', modules : ['ZLIB::ZLIB'])

CMake is automatically used after pkg-config fails when no method (or auto) was provided in the dependency options.

New compiler method `get_argument_syntax`

The compiler object now has get_argument_syntax method, which returns a string value of gcc, msvc, or an undefined value string value. This can be used to determine if a compiler uses gcc syntax (-Wfoo), msvc syntax (/w1234), or some other kind of arguments.

cc = meson.get_compiler('c')

if cc.get_argument_syntax() == 'msvc'
  if cc.has_argument('/w1235')
    add_project_arguments('/w1235', language : ['c'])
  endif
elif cc.get_argument_syntax() == 'gcc'
  if cc.has_argument('-Wfoo')
    add_project_arguments('-Wfoo', language : ['c'])
  endif
elif cc.get_id() == 'some other compiler'
  add_project_arguments('--error-on-foo', language : ['c'])
endif

Return `Disabler()` instead of not-found object

Functions such as dependency(), find_library(), find_program(), and python.find_installation() have a new keyword argument: disabler. When set to true those functions return Disabler() objects instead of not-found objects.

`introspect --projectinfo` can now be used without configured build directory

This allows IDE integration to get information about the project before the user has configured a build directory.

Before you could use meson.py introspect --projectinfo build-directory. Now you also can use meson.py introspect --projectinfo project-dir/meson.build.

The output is similar to the output with a build directory but additionally also includes information from introspect --buildsystem-files.

For example meson.py introspect --projectinfo test\ cases/common/47\ subproject\ options/meson.build This outputs (pretty printed for readability):

{
    "buildsystem_files": [
        "meson_options.txt",
        "meson.build"
    ],
    "name": "suboptions",
    "version": null,
    "descriptive_name": "suboptions",
    "subprojects": [
        {
            "buildsystem_files": [
                "subprojects/subproject/meson_options.txt",
                "subprojects/subproject/meson.build"
            ],
            "name": "subproject",
            "version": "undefined",
            "descriptive_name": "subproject"
        }
    ]
}

Both usages now include a new descriptive_name property which always shows the name set in the project.

Can specify keyword arguments with a dictionary

You can now specify keyword arguments for any function and method call with the kwargs keyword argument. This is perhaps best described with an example:

options = {'include_directories': include_directories('inc')}

...

executable(...
  kwargs: options)

The above code is identical to this:

executable(...
  include_directories: include_directories('inc'))

That is, Meson will expand the dictionary given to kwargs as if the entries in it had been given as keyword arguments directly.

Note that any individual argument can be specified either directly or with the kwarg dict but not both. If a key is specified twice, it is a hard error.

Manpages are no longer compressed implicitly

Earlier, the install_man command has automatically compressed installed manpages into .gz format. This collided with manpage compression hooks already used by various distributions. Now, manpages are installed uncompressed and distributors are expected to handle compressing them according to their own compression preferences.

Native config files

Native files (--native-file) are the counterpart to cross files (--cross-file), and allow specifying information about the build machine, both when cross compiling and when not.

Currently the native files only allow specifying the names of binaries, similar to the cross file, for example:

[binaries]
llvm-config = "/opt/llvm-custom/bin/llvm-config"

Will override the llvm-config used for native binaries. Targets for the host machine will continue to use the cross file.

Foreach `break` and `continue`

break and continue keywords can be used inside foreach loops.

items = ['a', 'continue', 'b', 'break', 'c']
result = []
foreach i : items
  if i == 'continue'
    continue
  elif i == 'break'
    break
  endif
  result += i
endforeach
# result is ['a', 'b']

You can check if an array contains an element like this:

my_array = [1, 2]
if 1 in my_array
# This condition is true
endif
if 1 not in my_array
# This condition is false
endif

You can check if a dictionary contains a key like this:

my_dict = {'foo': 42, 'foo': 43}
if 'foo' in my_dict
# This condition is true
endif
if 42 in my_dict
# This condition is false
endif
if 'foo' not in my_dict
# This condition is false
endif

Joining paths with /

For clarity and conciseness, we recommend using the / operator to separate path elements:

joined = 'foo' / 'bar'

Before Meson 0.49, joining path elements was done with the legacy join_paths function, but the / syntax above is now recommended.

joined = join_paths('foo', 'bar')

This only works for strings.

Position-independent executables

When b_pie option, or executable()'s pie keyword argument is set to true, position-independent executables are built. All their objects are built with -fPIE and the executable is linked with -pie. Any static library they link must be built with pic set to true (see b_staticpic option).

Deprecation warning in pkg-config generator

All libraries passed to the libraries keyword argument of the generate() method used to be associated with that generated pkg-config file. That means that any subsequent call to generate() where those libraries appear would add the filebase of the generate() that first contained them into Requires: or Requires.private: field instead of adding an -l to Libs: or Libs.private:.

This behaviour is now deprecated. The library that should be associated with the generated pkg-config file should be passed as first positional argument instead of in the libraries keyword argument. The previous behaviour is maintained but prints a deprecation warning and support for this will be removed in a future Meson release. If you cannot create the needed pkg-config file without this warning, please file an issue with as much details as possible about the situation.

For example this sample will write Requires: liba into libb.pc but print a deprecation warning:

liba = library(...)
pkg.generate(libraries : liba)

libb = library(...)
pkg.generate(libraries : [liba, libb])

It can be fixed by passing liba as first positional argument::

liba = library(...)
pkg.generate(liba)

libb = library(...)
pkg.generate(libb, libraries : [liba])

Subprojects download, checkout, update command-line

New command-line tool has been added to manage subprojects:

meson subprojects download to download all subprojects that have a wrap file.
meson subprojects update to update all subprojects to latest version.
meson subprojects checkout to checkout or create a branch in all git subprojects.

New keyword argument `is_default` to `add_test_setup()`

The keyword argument is_default may be used to set whether the test setup should be used by default whenever meson test is run without the --setup option.

add_test_setup('default', is_default: true, env: 'G_SLICE=debug-blocks')
add_test_setup('valgrind', env: 'G_SLICE=always-malloc', ...)
test('mytest', exe)

For the example above, running meson test and meson test --setup=default is now equivalent.

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