New features

rpath removal now more careful

On Linux-like systems, meson adds rpath entries to allow running apps in the build tree, and then removes those build-time-only rpath entries when installing. Rpath entries may also come in via LDFLAGS and via .pc files. Meson used to remove those latter rpath entries by accident, but is now more careful.

Added ability to specify targets in meson compile

It's now possible to specify targets in meson compile, which will result in building only the requested targets.

Usage: meson compile [TARGET [TARGET...]] TARGET has the following syntax: [PATH/]NAME[:TYPE]. NAME: name of the target from (e.g. foo from executable('foo', ...)). PATH: path to the target relative to the root file. Note: relative path for a target specified in the root is ./. TYPE: type of the target (e.g. shared_library, executable and etc)

PATH and/or TYPE can be ommited if the resulting TARGET can be used to uniquely identify the target in

For example targets from the following code:

shared_library('foo', ...)
static_library('foo', ...)
executable('bar', ...)

can be invoked with meson compile foo:shared_library foo:static_library bar.

Test protocol for gtest

Due to the popularity of Gtest (google test) among C and C++ developers meson now supports a special protocol for gtest. With this protocol meson injects arguments to gtests to output JUnit, reads that JUnit, and adds the output to the JUnit it generates.

meson.add_*_script methods accept new types

All three (add_install_script, add_dist_script, and add_postconf_script) now accept ExternalPrograms (as returned by find_program), Files, and the output of configure_file. The dist and postconf methods cannot accept other types because of when they are run. While dist could, in theory, take other dependencies, it would require more extensive changes, particularly to the backend.

meson.add_install_script(find_program('foo'), files('bar'))
meson.add_dist_script(find_program('foo'), files('bar'))
meson.add_postconf_script(find_program('foo'), files('bar'))

The install script variant is also able to accept custom_targets, custom_target indexes, and build targets (executables, libraries), and can use built executables a the script to run

installer = executable('installer', ...)
meson.add_install_script(installer, ...)
meson.add_install_script('', installer)

Machine file constants

Native and cross files now support string and list concatenation using the + operator, and joining paths using the / operator. Entries defined in the [constants] section can be used in any other section. An entry defined in any other section can be used only within that same section and only after it has been defined.

toolchain = '/toolchain'
common_flags = ['--sysroot=' + toolchain + '/sysroot']

c_args = common_flags + ['-DSOMETHING']
cpp_args = c_args + ['-DSOMETHING_ELSE']

c = toolchain + '/gcc'

Configure CMake subprojects with meson.subproject_options

Meson now supports passing configuration options to CMake and overriding certain build details extracted from the CMake subproject.

The new CMake configuration options object is very similar to the configuration data object object returned by configuration_data. It is generated by the subproject_options function

All configuration options have to be set before the subproject is configured and must be passed to the subproject method via the options key. Altering the configuration object won't have any effect on previous cmake.subproject calls.

Note: The cmake_options kwarg for the subproject function is now deprecated since it is replaced by the new options system.

find_program: Fixes when the program has been overridden by executable

When a program has been overridden by an executable, the returned object of find_program() had some issues:

# In a subproject:
exe = executable('foo', ...)
meson.override_find_program('foo', exe)

# In main project:
# The version check was crashing meson.
prog = find_program('foo', version : '>=1.0')

# This was crashing meson.

# New method to be consistent with built objects.

Response files enabled on Linux, reined in on Windows

Meson used to always use response files on Windows, but never on Linux.

It now strikes a happier balance, using them on both platforms, but only when needed to avoid command line length limits.

unstable-kconfig module renamed to unstable-keyval

The unstable-kconfig module is now renamed to unstable-keyval. We expect this module to become stable once it has some usage experience, specifically in the next or the following release

Fatal warnings in gnome.generate_gir()

gnome.generate_gir() now has fatal_warnings keyword argument to abort when a warning is produced. This is useful for example in CI environment where it's important to catch potential issues.

b_ndebug support for D language compilers

D Language compilers will now set -release/--release/-frelease (depending on the compiler) when the b_ndebug flag is set.

Meson test now produces JUnit xml from results

Meson will now generate a JUnit compatible XML file from test results. it will be in the meson-logs directory and is called testlog.junit.xml.

Config tool based dependencies no longer search PATH for cross compiling

Before 0.55.0 config tool based dependencies (llvm-config, cups-config, etc), would search system $PATH if they weren't defined in the cross file. This has been a source of bugs and has been deprecated. It is now removed, config tool binaries must be specified in the cross file now or the dependency will not be found.

Rename has_exe_wrapper -> can_run_host_binaries

The old name was confusing as it didn't really match the behavior of the function. The old name remains as an alias (the behavior hasn't changed), but is now deprecated.

String concatenation in meson_options.txt

It is now possible to use string concatenation (with the + opperator) in the meson_options.txt file. This allows splitting long option descriptions.

  type : 'string',
  value : 'optval',
  description : 'An option with a very long description' +
                'that does something in a specific context'

Wrap fallback URL

Wrap files can now define source_fallback_url and patch_fallback_url to be used in case the main server is temporaly down.

Clang coverage support

llvm-cov is now used to generate coverage information when clang is used as the compiler.

Local wrap source and patch files

It is now possible to use the patch_filename and source_filename value in a .wrap file without *_url to specify a local source / patch file. All local files must be located in the subprojects/packagefiles directory. The *_hash entries are optional with this setup.

Local wrap patch directory

Wrap files can now specify patch_directory instead of patch_filename in the case overlay files are local. Every files in that directory, and subdirectories, will be copied to the subproject directory. This can be used for example to add files to a project not using Meson build system upstream. The patch directory must be placed in subprojects/packagefiles directory.

Patch on all wrap types

patch_* keys are not limited to wrap-file any more, they can be specified for all wrap types.

Previously the link_language argument was only supposed to be allowed in executables, because the linker used needs to be the linker for the language that implements the main function. Unfortunately it didn't work in that case, and, even worse, if it had been implemented properly it would have worked for all targets. In 0.55.0 this restriction has been removed, and the bug fixed. It now is valid for executable and all derivative of library.

meson dist --no-tests

meson dist has a new option --no-tests to skip build and tests of generated packages. It can be used to not waste time for example when done in CI that already does its own testing.

Force fallback for

A newly-added --force-fallback-for command line option can now be used to force fallback for specific subprojects.


meson build --force-fallback-for=foo,bar

Implicit dependency fallback

dependency('foo') now automatically fallback if the dependency is not found on the system but a subproject wrap file or directory exists with the same name.

That means that simply adding subprojects/foo.wrap is enough to add fallback to any dependency('foo') call. It is however requires that the subproject call meson.override_dependency('foo', foo_dep) to specify which dependency object should be used for foo.

Wrap file provide section

Wrap files can define the dependencies it provides in the [provide] section. When foo.wrap provides the dependency foo-1.0 any call do dependency('foo-1.0') will automatically fallback to that subproject even if no fallback keyword argument is given. See Wrap documentation.

find_program() fallback

When a program cannot be found on the system but a wrap file has its name in the [provide] section, that subproject will be used as fallback.

Test scripts are given the exe wrapper if needed

Meson will now set the MESON_EXE_WRAPPER as the properly wrapped and joined representation. For Unix-like OSes this means python's shelx.join, on Windows an implementation that attempts to properly quote windows argument is used. This allow wrapper scripts to run test binaries, instead of just skipping.

for example, if the wrapper is ['emulator', '--script'], it will be passed as MESON_EXE_WRAPPER="emulator --script".

Added ability to specify backend arguments in meson compile

It's now possible to specify backend specific arguments in meson compile.

Usage: meson compile [--vs-args=args] [--ninja-args=args]

  --ninja-args NINJA_ARGS    Arguments to pass to `ninja` (applied only on `ninja` backend).
  --vs-args VS_ARGS          Arguments to pass to `msbuild` (applied only on `vs` backend).

These arguments use the following syntax:

If you only pass a single string, then it is considered to have all values separated by commas. Thus invoking the following command:

$ meson compile --ninja-args=-n,-d,explain

would add -n, -d and explain arguments to ninja invocation.

If you need to have commas or spaces in your string values, then you need to pass the value with proper shell quoting like this:

$ meson compile "--ninja-args=['a,b', 'c d']"

Introspection API changes

dumping the AST (--ast): new in 0.55.0

  • prints the AST of a as JSON

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