Meson

If you are using Meson Build as your build system, you can use the Meson build helper. Specially useful with the pkg_config that will generate the .pc files of our requirements, then Meson() build helper will locate them automatically.

 from conans import ConanFile, tools, Meson
 import os

 class ConanFileToolsTest(ConanFile):
     generators = "pkg_config"
     requires = "LIB_A/0.1@conan/stable"
     settings = "os", "compiler", "build_type"

     def build(self):
         meson = Meson(self)
         meson.configure(build_folder="build")
         meson.build()

Constructor

class Meson(object):

    def __init__(self, conanfile, backend=None, build_type=None)
Parameters:

  • conanfile (Required): Use self inside a conanfile.py.

  • backend (Optional, Defaulted to None): Specify a backend to be used, otherwise it will use "Ninja".

  • build_type (Optional, Defaulted to None): Force to use a build type, ignoring the value from the settings.

Methods

configure()

def configure(self, args=None, defs=None, source_folder=None, build_folder=None,
              pkg_config_paths=None, cache_build_folder=None, append_vcvars=False)

Configures Meson project with the given parameters.

Parameters:

  • args (Optional, Defaulted to None): A list of additional arguments to be passed to the configure script. Each argument will be escaped according to the current shell. No extra arguments will be added if args=None.

  • defs (Optional, Defaulted to None): A list of definitions.

  • source_folder (Optional, Defaulted to None): Meson’s source directory where meson.build is located. The default value is the self.source_folder. Relative paths are allowed and will be relative to self.source_folder.

  • build_folder (Optional, Defaulted to None): Meson’s output directory. The default value is the self.build_folder if None is specified. The Meson object will store build_folder internally for subsequent calls to build().

  • pkg_config_paths (Optional, Defaulted to None): A list containing paths to locate the pkg-config files (*.pc). If None, it will be set to conanfile.build_folder.

  • cache_build_folder (Optional, Defaulted to None): Subfolder to be used as build folder when building the package in the local cache. This argument doesn’t have effect when the package is being built in user folder with conan build but overrides build_folder when working in the local cache. See self.in_local_cache.

  • append_vcvars (Optional, Defaulted to False): When a Visual Studio environment is activated by the build helper, append it to respect existing environment. Meson helper uses the Ninja generator and needs to call vcvars to set the VS environment. By default the vcvars is pre-pended to the environment, taking precedence. With append_vcvars=True, the vcvars will append to the end of the environment (for “list” environment variables, like PATH), instead of pre-pending, so the existing environment takes precedence.

build()

def build(self, args=None, build_dir=None, targets=None)

Builds Meson project with the given parameters.

Parameters:

  • args (Optional, Defaulted to None): A list of additional arguments to be passed to the make command. Each argument will be escaped according to the current shell. No extra arguments will be added if args=None.

  • build_dir (Optional, Defaulted to None): Build folder. If None, it will be set to conanfile.build_folder.

  • targets (Optional, Defaulted to None): A list of targets to be built. No targets will be added if targets=None.

Example

A typical usage of the Meson build helper, if you want to be able to both execute conan create and also build your package for a library locally (in your user folder, not in the local cache), could be:

from conans import ConanFile, Meson

class HelloConan(ConanFile):
    name = "Hello"
    version = "0.1"
    settings = "os", "compiler", "build_type", "arch"
    generators = "pkg_config"
    exports_sources = "src/*"
    requires = "zlib/1.2.11"

    def build(self):
        meson = Meson(self)
        meson.configure(source_folder="%s/src" % self.source_folder,
                        build_folder="build")
        meson.build()

    def package(self):
        self.copy("*.h", dst="include", src="src")
        self.copy("*.lib", dst="lib", keep_path=False)
        self.copy("*.dll", dst="bin", keep_path=False)
        self.copy("*.dylib*", dst="lib", keep_path=False)
        self.copy("*.so", dst="lib", keep_path=False)
        self.copy("*.a", dst="lib", keep_path=False)

    def package_info(self):
        self.cpp_info.libs = ["hello"]

Note the pkg_config generator, which generates .pc files (zlib.pc from the example above ), which are understood by Meson to process dependencies information (no need for a meson generator).

The layout is:

<folder>
  | - conanfile.py
  | - src
      | - meson.build
      | - hello.cpp
      | - hello.h

And the meson.build could be as simple as:

project('hello',
        'cpp',
        version : '0.1.0'
        default_options : ['cpp_std=c++11']
        )

library('hello',
        ['hello.cpp'],
        dependencies: [dependency('zlib')]
        )

This allows, to create the package with conan create as well as to build the package locally:

$ cd <folder>
$ conan create . user/testing
# Now local build
$ mkdir build && cd build
$ conan install ..
$ conan build ..