Since we now guarantee that Rust and C/C++ will have assertions both on
or both off, we can give guidance about using `cfg(debug_assertions)` to
wrap code using `#ifdef NDEBUG`.
This has a couple of advantages over rolling it by hand:
1. it correctly handles include_directories objects, which is always
handy
2. it correctly generates a depfile for you, which makes it more
reliable
3. it requires less typing
Like other language specific modules this module is module for holding
rust specific helpers. This commit adds a test() function, which
simplifies using rust's internal unittest mechanism.
Rust tests are generally placed in the same code files as they are
testing, in contrast to languages like C/C++ and python which generally
place the tests in separate translation units. For meson this is
somewhat problematic from a repetition point of view, as the only
changes are generally adding --test, and possibly some dependencies.
The rustmod.test() method provides a mechanism to remove the repatition:
it takes a rust target, copies it, and then addes the `--test` option,
then creates a Test() target with the `rust` protocol. You can pass
additional dependencies via the `dependencies` keyword. This all makes
for a nice, DRY, test definition.
Dylan Baker