New features

Python minimum version is now 3.5

Meson will from this version on require Python version 3.5 or newer.

Config-Tool based dependencies can be specified in a cross file

Tools like LLVM and pcap use a config tool for dependencies, this is a script or binary that is run to get configuration information (cflags, ldflags, etc) from.

These binaries may now be specified in the binaries section of a cross file.

[binaries]
cc = ...
llvm-config = '/usr/bin/llvm-config32'

Visual Studio C# compiler support

In addition to the Mono C# compiler we also support Visual Studio's C# compiler. Currently this is only supported on the Ninja backend.

Removed two deprecated features

The standalone find_library function has been a no-op for a long time. Starting with this version it becomes a hard error.

There used to be a keywordless version of run_target which looked like this:

run_target('targetname', 'command', 'arg1', 'arg2')

This is now an error. The correct format for this is now:

run_target('targetname',
  command : ['command', 'arg1', 'arg2'])

Experimental FPGA support

This version adds support for generating, analysing and uploading FPGA programs using the IceStorm toolchain. This support is experimental and is currently limited to the iCE 40 series of FPGA chips.

FPGA generation integrates with other parts of Meson seamlessly. As an example, here is an example project that compiles a simple firmware into Verilog and combines that with an lm32 softcore processor.

Generator outputs can preserve directory structure

Normally when generating files with a generator, Meson flattens the input files so they all go in the same directory. Some code generators, such as Protocol Buffers, require that the generated files have the same directory layout as the input files used to generate them. This can now be achieved like this:

g = generator(...) # Compiles protobuf sources
generated = gen.process('com/mesonbuild/one.proto',
  'com/mesonbuild/two.proto',
  preserve_path_from : meson.current_source_dir())

This would cause the following files to be generated inside the target private directory:

com/mesonbuild/one.pb.h
com/mesonbuild/one.pb.cc
com/mesonbuild/two.pb.h
com/mesonbuild/two.pb.cc

Hexadecimal string literals

Hexadecimal integer literals can now be used in build and option files.

int_255 = 0xFF

b_ndebug : if-release

The value if-release can be given for the b_ndebug project option.

This will make the NDEBUG pre-compiler macro to be defined for release type builds as if the b_ndebug project option had the value true defined for it.

install_data() defaults to {datadir}/{projectname}

If install_data() is not given an install_dir keyword argument, the target directory defaults to {datadir}/{projectname} (e.g. /usr/share/myproj).

install_subdir() supports strip_directory

If strip_directory=true install_subdir() installs directory contents instead of directory itself, stripping basename of the source directory.

Integer options

There is a new integer option type with optional minimum and maximum values. It can be specified like this in the meson_options.txt file:

option('integer_option', type : 'integer', min : 0, max : 5, value : 3)

New method meson.project_license()

The meson builtin object now has a project_license() method that returns a list of all licenses for the project.

Rust cross-compilation

Cross-compilation is now supported for Rust targets. Like other cross-compilers, the Rust binary must be specified in your cross file. It should specify a --target (as installed by rustup target) and a custom linker pointing to your C cross-compiler. For example:

[binaries]
c = '/usr/bin/arm-linux-gnueabihf-gcc-7'
rust = [
    'rustc',
    '--target', 'arm-unknown-linux-gnueabihf',
    '-C', 'linker=/usr/bin/arm-linux-gnueabihf-gcc-7',
]

Rust compiler-private library disambiguation

When building a Rust target with Rust library dependencies, an --extern argument is now specified to avoid ambiguity between the dependency library, and any crates of the same name in rustc's private sysroot.

Project templates

Meson ships with predefined project templates. To start a new project from scratch, simply go to an empty directory and type:

meson init --name=myproject --type=executable --language=c

Improve test setup selection

Test setups are now identified (also) by the project they belong to and it is possible to select the used test setup from a specific project. E.g. to use a test setup some_setup from project some_project for all executed tests one can use

meson test --setup some_project:some_setup

Should one rather want test setups to be used from the same project as where the current test itself has been defined, one can use just

meson test --setup some_setup

In the latter case every (sub)project must have a test setup some_setup defined in it.

Can use custom targets as Windows resource files

The compile_resources() function of the windows module can now be used on custom targets as well as regular files.

Can promote dependencies with wrap command

The promote command makes it easy to copy nested dependencies to the top level.

meson wrap promote scommon

This will search the project tree for a subproject called scommon and copy it to the top level.

If there are many embedded subprojects with the same name, you have to specify which one to promote manually like this:

meson wrap promote subprojects/s1/subprojects/scommon

Yielding subproject option to superproject

Normally project options are specific to the current project. However sometimes you want to have an option whose value is the same over all projects. This can be achieved with the new yield keyword for options. When set to true, getting the value of this option in meson.build files gets the value from the option with the same name in the master project (if such an option exists).