title: Release 0.45 short-description: Release notes for 0.45 ...
Meson will from this version on require Python version 3.5 or newer.
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'
In addition to the Mono C# compiler we also support Visual Studio's C# compiler. Currently this is only supported on the Ninja backend.
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'])
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.
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 integer literals can now be used in build and option files.
int_255 = 0xFF
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).
If strip_directory=true install_subdir() installs directory contents instead of directory itself, stripping basename of the source directory.
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)
The meson builtin object now has a project_license() method that returns a list of all licenses for the project.
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', ]
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.
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
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.
The compile_resources() function of the windows module can now be used on custom targets as well as regular files.
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
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).