Syntax for passing kwargs to functions using the dictionary object

[nirbheek]

I have three main use-cases for this:

1. Factoring out kwargs that are applied to a number of targets at once

2. Conditionally setting kwargs based on

   • Build option (to install tests, tools, etc)
   • Target platform (name_suffix/name_prefix, etc)
   • Meson version (to write code that doesn't print warnings on any meson version)

3. The ability to write helper modules that will output kwargs for targets that follow a specific convention, such as a module for libtool naming and versioning, which many projects porting from Autotools need to maintain ABI compatibility. Currently all these projects duplicate code to calculate these and set them. Ex:

   • Library versioning
   • Library naming
   • Library internal versioning on macOS

[nirbheek]

CCing interested parties: @MathieuDuponchelle @Akaricchi

[nirbheek]

Idea from #4019:

Build the same library as static and shared with different c_args::

tspec = {
  'static': {'c_args': ['-DFOO_STATIC'], 'target_type': 'static_library'},
  'shared': {'c_args': [], 'target_type': 'shared_library'},
}
library('foo', sources, target_spec: tspec)