This also makes it more consistent with get_pkgconfig_variable() which
always return empty value instead of failing when the variable does not
exist. Linking that to self.required makes no sense and was never
documented any way.
If the dependency permits it, we can just do a PATH search instead of
mandating that it be listed in the cross file. This is useful for the
limited case where a specific dependency is known to be compatible with
any machine choice.
Mark the pybind11 dependency as supporting this. It's a valid choice
because pybind11 is a header-only C++ library.
The latest release of libpcap added argument validation to pcap-config,
but still doesn't support --version. The next version of libpcap will
support --version.
Add support for config-tool dependencies which expect to break on
--version, to fallback to an option that does not error out or print
version info, for sanity checking.
dep.get_variable() only supports string values for pkg-config and
config-tool, because those interfaces use text communication, and
internal variables (from declare_dependency) operate the same way.
CMake had an oddity, where get_variable doesn't document that it allows
list values but apparently it miiiiiight work? Actually getting that
kind of result would be dangerously inconsistent though. Also, CMake
does not support lists so it's a lie. Strings that are *treated* as
lists with `;` splitting don't count...
We could do two things here:
- raise an error
- treat it as a string and return a string
It's not clear what the use case of get_variable() on a maybe-list is,
and should probably be a hard error. But that's controversial, so
instead we just return the original `;`-delimited string. It is probably
the wrong thing, but users are welcome to cope with that somehow on
their own.
Both of these are artifacts of the time before Dependency Factories,
when a dependency that could be discovered multiple ways did ugly stuff
like finding a specific dependency, then replacing it's own attributes
with that dependency's attributes. We don't have cases of that left in
the tree, so let's get rid of this code too
This allow mypy to catch cases where we accidently assign the dependency
name to the type_name, as it sees them as having different types (though
at runtime they're all strings).
Xavier Claessens