Preliminary, 0.42.0 has not been released yet.

New features

Distribution tarballs from Mercurial repositories

Creating distribution tarballs can now be made out of projects based on Mercurial. As before, this remains possible only with the Ninja backend.

Keyword argument verification

Meson will now check the keyword arguments used when calling any function and print a warning if any of the keyword arguments is not known. In the future this will become a hard error.

Add support for Genie to Vala compiler

The Vala compiler has an alternative syntax, Genie, that uses the .gs file extension. Meson now recognises and uses Genie files.

Pkgconfig support for additional cflags

The Pkgconfig module object can add arbitrary extra cflags to the Cflags value in the .pc file, using the "extra_cflags" keyword:

pkg.generate(libraries : libs,
             subdirs : h,
             version : '1.0',
             name : 'libsimple',
             filebase : 'simple',
             description : 'A simple demo library.',
             extra_cflags : '-Dfoo' )

Base options accessible via get_option()

Base options are now accessible via the get_option() function.

uses_lto = get_option('b_lto')

Allow crate type configuration for Rust compiler

Rust targets now take an optional rust_crate_type keyword, allowing you to set the crate type of the resulting artifact. Valid crate types are dylib or cdylib for shared libraries, and rlib or staticlib for static libraries. For more, see Rust's linkage reference.

Simultaneous use of Address- and Undefined Behavior Sanitizers

Both the address- and undefined behavior sanitizers can now be used simultaneously by passing -Db_sanitize=address,undefined to Meson.

Unstable SIMD module

A new experimental module to compile code with many different SIMD instruction sets and selecting the best one at runtime. This module is unstable, meaning its API is subject to change in later releases. It might also be removed altogether.

Import libraries for executables on Windows

The new keyword implib to executable() allows generation of an import library for the executable.

Added build_rpath keyword argument

You can specify build_rpath : '/foo/bar' in build targets and the given path will get added to the target's rpath in the build tree. It is removed during the install step.

Meson will print a warning when the user tries to add an rpath linker flag manually, e.g. via link_args to a target. This is not recommended because having multiple rpath causes them to stomp on each other. This warning will become a hard error in some future release.