build_native #

Compile native extensions with package:build, via CMake.

This is a 2-step build process:

1. Build *.{c,cc,cpp} files to .o.
2. Link files into a shared library.

Ultimately, to build everything, you will just need to run pub run build_runner build.

The goal of this package is to use existing infrastructure to build native extensions. Eventually, though, it might be nicer to perform builds in an after_install script in a pubspec.yaml.

I've actually submitted at PR to Pub for such functionality, so instant, portable builds of native extensions might be on their way soon.

Usage #

build_native requires only very little configuration. However, this means that it can only serve one purpose: invoking the compiler on the user's system.

Source Files #

Also, because of the nature of package:build, each input can only create one output. For *.c, *.cc, and *.cpp, files, the system compiler is invoked to create a .o file. To override this, set the CC environment variable when compiling C, or the CXX environment variable when compiling C++.

Files named *.macos.{c,cc,cpp} will only build on Mac. The same applies to linux and windows. This can be used to apply platform-specific settings in your build.

Master Build File #

To perform linking, include an lib<extension_name>.build_native.yaml file in the directory where the extension should be built.

It should contain a list of source files to link together.

Note that these should all be asset ID's.

The simplest example, libsample_extension.build_native.yaml:

sources:
  - example|src/sample_extension.cc

See example/ for more.

All supported options:

flags:
  - "-O2"
sources:
  - example|sample_extension.cc
  - example|sample_extension.macos.cc # Will only be included on MacOS; ignored elsewhere
link:
  - example|some_lib.o
define:
  foo: bar
  DEBUG:

Platform-Specific Options #

To specify options that should only apply to a given platform, add a <extension_name>.<platform_name>.macos.build_native.yaml file, for example, foo_bar.macos.build_native.yaml. This will be merged into the main options.

Platforms available: macos, windows, linux.

By providing this as the PLATFORM environment variable, you can override this.

Windows #

Save yourself a hassle by running the build within the Visual Studio Developer Command Prompt.

Regardless, executables like cl.exe and link.exe should be available. Otherwise:

To enable a 64-bit toolset: https://docs.microsoft.com/en-us/cpp/build/how-to-enable-a-64-bit-visual-cpp-toolset-on-the-command-line

vcvarsall might be contained in: C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Auxiliary\Build

Unix #

On Unix, if you some error like this:

fatal error: bits/c++config.h: No such file or directory

Then run:

sudo apt-get install -y gcc-multilib g++-multilib