Explicitly mention that the project definition is invalid, and clarify
that project is `project()` -- a function.
Also try to walk the directory tree upward, and if there are parent
meson.build files, just say this isn't the project root, and "maybe you
meant to run meson there instead?"
This won't catch calls to subdir('foo/bar') but we can't be perfect,
only better than before and catch the *majority* of such cases, and
hopefully it's a lot more clear if meson protests that the project is
"invalid, there is no project() function", where the user should look
for a potential solution.
Fixes#3426
We recommend people use declare_dependency and access it via
dependency() in a parent project. But this requires a wrap file (or to
use override_dependency and an explicit subproject call).
Let's actually mention that.
Fixes#9146
This is really, really, annoying. What we really want is (psuedocode):
```python
class SubValues(TypedDict[str, str], total=False):
@INPUT@: T.List[str]
@OUTPUT@: T.List[str]
```
Which would specifiy that `@INPUT@` and `@OUTPUT@` *may* be present and
if they are, then they are lists. There may be additional keys, which
have a single string as a value. Of course there is currently no way to
do that with typing, so we have to instead take a union type and then
use asserts to help the type checker unerstand this.
More info: https://github.com/python/mypy/issues/4617
get_compiler_for_source and classify_unity_sources are both wrong, in
that they expect to be given a seqence of strings, but they really
should take a `Sequence[str | File]`.
Additionally, they're using `CompilerType`, which we don't need anymore,
and should stop using, most methods for the Compiler are actually
defined in the base compiler class.
Again, this is not complete and is just enough for backend.py. Again,
typing these is complicated massively by the layering violations in the
Target classes and the interpreter.
This is not complete, it's just enough for backend/backend.py. A more
completely typing would be more difficult, especially whithout
untangling the layering violation between the build targets and the
interpreter.