(and for * patterns in match)
Since `PhaseDependentFlow` uses the following predicate, that relies on
.getScope() to be present for there to be any importTimeFlow (flow at
toplevel scope), it's important that data-flow nodes implement `.getScope`.
```
private predicate isTopLevel(Node node) { node.getScope() instanceof Module }
```
By implementing getScope, we can now rely on default implementation of
`getEnclosingCallable` in DataFlow::Node:
```
/** Gets the enclosing callable of this node. */
DataFlowCallable getEnclosingCallable() { result = getCallableScope(this.getScope()) }
```
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`.
mostly removing of nodes from the graph.
One result lost:
```
check("submodule.submodule_attr", submodule.submodule_attr, "submodule_attr", globals()) #$ MISSING:prints=submodule_attr
```
This commit removes SSA nodes from the data flow graph. Specifically, for a definition and use such as
```python
x = expr
y = x + 2
```
we used to have flow from `expr` to an SSA variable representing x and from that SSA variable to the use of `x` in the definition of `y`. Now we instead have flow from `expr` to the control flow node for `x` at line 1 and from there to the control flow node for `x` at line 2.
Specific changes:
- `EssaNode` from the data flow layer no longer exists.
- Several glue steps between `EssaNode`s and `CfgNode`s have been deleted.
- Entry nodes are now admitted as `CfgNodes` in the data flow layer (they were filtered out before).
- Entry nodes now have a new `toString` taking into account that the module name may be ambigous.
- Some tests have been rewritten to accomodate the changes, but only `python/ql/test/experimental/dataflow/basic/maximalFlowsConfig.qll` should have semantic changes.
- Comments have been updated
- Test output has been updated, but apart from `python/ql/test/experimental/dataflow/basic/maximalFlows.expected` only `python/ql/test/experimental/dataflow/typetracking-summaries/summaries.py` should have a semantic change. This is a bonus fix, probably meaning that something was never connected up correctly.
