Or, more generally, any copy step, as these presumably do not preserve
object identity.
(Arguably, `copy` could still be susceptible to interior mutability, but
I think that's outside the scope of this query anyway.)
There are two issues with `deepcopy` here. Firstly, the `deepcopy` function itself
has a mutable default value in its parameter `_nil` (set to the empty list by default).
Now, this value is never actually returned from `deepcopy`, as it is only used as a
sentinel, but our analysis is not clever enough to see this. Thus, it thinks that this
mutable default is returned, and hence the result of any call to `deepcopy` is a
potential source.
To remedy this, I opted to simply exclude all sources that originate from within the
standard library. It is very unlikely for any of the sources in the standard library
to be legit.
Secondly, `deepcopy` -- by virtue of being a function that we model as preserving
values -- admits data-flow through its calls, but this is not correct for the mutable
default query, as it is here the _identity_ of the default value in question that is
important. Thus, we get spurious flow through `deepcopy` for this specific query.
Moves the existing tests into the `ModificationOfParameterWithDefault` subdirectory
which already contained a bunch more tests. In the process, I also removed some
duplicated test cases.
Since some sanitisers don't handle backslashes correctly, I updated the data-flow configuration to incorporate a flow state tracking whether or not backslashes have been eliminated or converted to forward slashes.
In reality, we only want to model this as a `rest_framework.response.Response`, since our .qll modeling is more precise for rest-framework responses than if we also modeled it as a basic django http response. (specifically, that default mime-type handling is way different).
mostly removing of nodes from the graph.
One result lost:
```
check("submodule.submodule_attr", submodule.submodule_attr, "submodule_attr", globals()) #$ MISSING:prints=submodule_attr
```
TODO:
The member predicate `LibraryLambdaMethod::getACall` is
currently too permissive.
Ideally, we would have `libraryCallHasLambdaArg`
as in Ruby. But even a more precise
`libraryCall` predicate might be fine.
This provides variable capture in standard situations:
- nested functions
- lambdas
There are some deficiencies:
- we do not yet handle objects capturing variables.
- we do not handle variables captured via the `nonlocal` keyword.
This should be solved at the AST level, though, and then it
should "just work".
There are still inconsistencies in the case where
a `SynthesizedCaptureNode` has a comprehensions
as its enclosing callable. In this case,
`TFunction(cn.getEnclosingCallable())` is not
defined and so getEnclosingCallable does not exist
for the `CaptureNode`.
I fixed it in both predicates... I think we might still be able to remove
`newDirectAlias` -- but with it being better, it will allow us to better test if `newImportAlias` actually cover everything we need!
