Change the code to store D properties as plain data. Only convert them
to compiler flags in the backend. This also means we can fully parse D
arguments without needing to know the compiler being used.
Of course D compilers have different flags to set some important
D-specific settings. This adds a simple method to change these flags in
a compiler-agnostic way in Meson.
This replaces the previous `unittest_args` method with a more generic
variant.
Actually, GDC supports shared libraries since version 6.2, but on Debian
there are still issues with that version due to the standard library not
being compiled with PIC.
Therefore, we make a very conservative assumption here and only enable
the tests for GDC >= 7.0
This allows us to disable the shared library test if the GNU D compiler
is detected.
This is useful, because gdc can not yet build proper shared libraries.
We also add a new test here which tests versioning of D shared
libraries.
D allows programmers to define their tests alongside the actual code in
a unittest scope[1].
When compiled with a special flag, the compiler will build a binary
containing the tests instead of the actual application.
This is a strightforward and easy way to run tests and works well with
Mesons test() command.
Since using just one flag name to enable unittest mode would be too
boring, compiler developers invented multiple ones.
Adding this helper method makes it easy for people writing Meson build
descriptions for D projects to enable unittestmode.
[1]: https://dlang.org/spec/unittest.html
Jussi Pakkanen
Matthias Klumpp
Mike Wey
Nirbheek Chauhan