This allows a CustomTarget to be indexed, and the resulting indexed
value (a CustomTargetIndex type), to be used as a source in other
targets. This will confer a dependency on the original target, but only
inserts the source file returning by index the original target's
outputs. This can allow a CustomTarget that creates both a header and a
code file to have it's outputs split, for example.
Fixes#1470
This also adds a "# noqa: F401" comment on an unused "import lzma",
which we are using it in a try/except block that is being used to
check if the lzma module is importable; of course it is unused.
v2: This turned out to be a little tricky.
mesonbuild/modules/__init__.py had the "unused" import:
from ..interpreterbase import permittedKwargs, noKwargs
However, that meant that the various modules could do things like:
from . import noKwargs # "." is "mesonbuild.modules"
Which breaks when you remove __init__.py's "unused" import. I
could have tagged that import with "# noqa: F401", but instead I
chose to have each of the module import directly from
"..interpreterbase" instead of ".".
Jussi Pakkanen
Niklas Claesson
Dylan Baker
Luke Shumaker