Instead of asking the ExtractedObjects, but with a hook back into the backend,
use the existing function in the backend itself. This fixes using the
extract_objects(...) of a generated source file in a custom_target.
It should also fix recursive extract_all_objects with the Xcode backend.
Fixes: #10394
That method had nothing specific to the backend, it's purely a Target
method. This allows to cache the OptionOverrideProxy object on the
Target instance instead of creating a new one for each option lookup.
This caught a couple of cases of us doing:
```python
for i in range(len(x)):
v = x[i]
```
which are places to use enumerate instead.
It also caught a couple of cases of:
```python
assert len(x) == len(y)
for i in range(len(x)):
xv = x[i]
yv = y[i]
```
Which should instead be using zip()
```python
for xv, yv in zip(x, y):
...
```
We have a lot of these. Some of them are harmless, if unidiomatic, such
as `if (condition)`, others are potentially dangerous `assert(...)`, as
`assert(condtion)` works as expected, but `assert(condition, message)`
will result in an assertion that never triggers, as what you're actually
asserting is `bool(tuple[2])`, which will always be true.
This didn't actually catch what it's supposed to, which is cases of:
```python
for x in dict.keys():
y = dict[x]
```
But it did catch one unnecessary use of keys(), and one case where we
were doing something in an inefficient way. I've rewritten:
```python
if name.value in [x.value for x in self.kwargs.keys() if isinstance(x, IdNode)]:
```
as
``python
if any((isinstance(x, IdNode) and name.value == x.value) for x in self.kwargs):
```
Which avoids doing two iterations, one to build the list, and a
second to do a search for name.value in said list, which does a single
short circuiting walk, as any returns as soon as one check returns True.
Paolo Bonzini
Eli Schwartz
Jussi Pakkanen
Xavier Claessens
Dylan Baker