problem is:
```
14294 ~33% {1} r23 = r21 UNION r22
13626 ~0% {2} | JOIN WITH `DataFlowPublic::Node.getEnclosingCallable/0#dispred#be95825a` ON FIRST 1 OUTPUT Rhs.1, Lhs.0
11871493 ~2% {2} | JOIN WITH `DataFlowPublic::Node.getEnclosingCallable/0#dispred#be95825a_10#join_rhs` ON FIRST 1 OUTPUT Rhs.1, Lhs.1
6810938 ~3% {2} | JOIN WITH num#DataFlowPublic::TCfgNode#2cd2fb22_10#join_rhs ON FIRST 1 OUTPUT Rhs.1, Lhs.1
0 ~0% {4} | JOIN WITH `DataFlowDispatch::resolveMethodCall/4#3067f1f1#reorder_0_3_1_2#prev` ON FIRST 2 OUTPUT Rhs.3, Lhs.1, Lhs.0, Rhs.2
0 ~0% {4} | JOIN WITH num#DataFlowDispatch::CallTypeClassMethod#3508c3e5 ON FIRST 1 OUTPUT Lhs.3, Lhs.2, Lhs.0, Lhs.1
0 ~0% {4} | JOIN WITH `DataFlowDispatch::resolveCall/3#454c02d8#reorder_1_0_2#prev` ON FIRST 3 OUTPUT Lhs.3, Lhs.1, Lhs.0, Lhs.2
0 ~0% {5} | JOIN WITH num#DataFlowDispatch::TSelfArgumentPosition#de6d64b8 CARTESIAN PRODUCT OUTPUT Lhs.1, Lhs.2, Lhs.3, Lhs.0, Rhs.0
```
that is, it does cartesian product of DataFlowPublic::Node.getEnclosingCallable
After fix
```
14294 ~33% {1} r23 = r21 UNION r22
0 ~0% {4} | JOIN WITH `DataFlowDispatch::resolveMethodCall/4#3067f1f1#reorder_3_0_1_2#prev` ON FIRST 1 OUTPUT Rhs.3, Lhs.0, Rhs.1, Rhs.2
0 ~0% {4} | JOIN WITH num#DataFlowDispatch::CallTypeClassMethod#3508c3e5 ON FIRST 1 OUTPUT Lhs.3, Lhs.2, Lhs.0, Lhs.1
0 ~0% {4} | JOIN WITH `DataFlowDispatch::resolveCall/3#454c02d8#reorder_1_0_2#prev` ON FIRST 3 OUTPUT Lhs.1, Lhs.3, Lhs.0, Lhs.2
0 ~0% {5} | JOIN WITH num#DataFlowPublic::TCfgNode#2cd2fb22 ON FIRST 1 OUTPUT Rhs.1, Lhs.1, Lhs.0, Lhs.2, Lhs.3
0 ~0% {5} | JOIN WITH `DataFlowPublic::Node.getEnclosingCallable/0#dispred#be95825a` ON FIRST 1 OUTPUT Lhs.1, Rhs.1, Lhs.2, Lhs.3, Lhs.4
0 ~0% {4} | JOIN WITH `DataFlowPublic::Node.getEnclosingCallable/0#dispred#be95825a` ON FIRST 2 OUTPUT Lhs.0, Lhs.2, Lhs.3, Lhs.4
0 ~0% {5} | JOIN WITH num#DataFlowDispatch::TSelfArgumentPosition#de6d64b8 CARTESIAN PRODUCT OUTPUT Lhs.1, Lhs.2, Lhs.3, Lhs.0, Rhs.0
```
Overall stats
(old)
Pipeline standard for DataFlowDispatch::getCallArg/5#21589076@b30c7vxg was evaluated in 51 iterations totaling 54ms (delta sizes total: 38247).
==>
(new)
Pipeline standard for DataFlowDispatch::getCallArg/5#21589076@c1559vxu was evaluated in 51 iterations totaling 28ms (delta sizes total: 38247).
No major performance impact, more of a learning example for myself (had +3000 join order badness).
Initial tuple counts
```
Evaluated recursive predicate SqlAlchemy::SqlAlchemy::Connection::ConnectionConstruction#45e716e0@594cfx2g in 1ms on iteration 1 (delta size: 4).
Evaluated relational algebra for predicate SqlAlchemy::SqlAlchemy::Connection::ConnectionConstruction#45e716e0@594cfx2g on iteration 1 running pipeline base with tuple counts:
37793 ~0% {3} r1 = JOIN `ApiGraphs::API::Node.getACall/0#dispred#312deb92_10#join_rhs` WITH DataFlowPublic::CallCfgNode#b8ddbf81 ON FIRST 1 OUTPUT Lhs.1, Lhs.0, Rhs.1
0 ~0% {2} | JOIN WITH `SqlAlchemy::SqlAlchemy::Connection::classRef/0#565fc3ad` ON FIRST 1 OUTPUT Lhs.1, Lhs.2
30 ~0% {5} r2 = JOIN DataFlowPublic::CallCfgNode#b8ddbf81 WITH `DataFlowPublic::MethodCallNode.calls/2#dispred#1dd1e0f4#ffb` ON FIRST 1 OUTPUT Lhs.0, Lhs.1, Rhs.1, Rhs.2, _
{4} | REWRITE WITH NOT [NOT [Tmp.4 := "begin", TEST InOut.3 = Tmp.4], NOT [Tmp.4 := "connect", TEST InOut.3 = Tmp.4]] KEEPING 4
21 ~0% {3} | SCAN OUTPUT In.2, In.0, In.1
4 ~0% {2} | JOIN WITH `SqlAlchemy::SqlAlchemy::Engine::instance/0#1828baef` ON FIRST 1 OUTPUT Lhs.1, Lhs.2
4 ~0% {2} r3 = r1 UNION r2
return r3
```
which is fixed by the only_bind_out
```
Evaluated recursive predicate SqlAlchemy::SqlAlchemy::Connection::ConnectionConstruction#45e716e0@49effxtg in 0ms on iteration 1 (delta size: 0).
Evaluated relational algebra for predicate SqlAlchemy::SqlAlchemy::Connection::ConnectionConstruction#45e716e0@49effxtg on iteration 1 running pipeline base with tuple counts:
0 ~0% {1} r1 = JOIN `SqlAlchemy::SqlAlchemy::Connection::classRef/0#565fc3ad` WITH `ApiGraphs::API::Node.getACall/0#dispred#312deb92` ON FIRST 1 OUTPUT Rhs.1
0 ~0% {2} | JOIN WITH DataFlowPublic::CallCfgNode#b8ddbf81 ON FIRST 1 OUTPUT Lhs.0, Rhs.1
return r1
```
We also had this initial problem
```
Evaluated recursive predicate SqlAlchemy::SqlAlchemy::Connection::ConnectionConstruction#45e716e0@594cfx2g in 1ms on iteration 4 (delta size: 0).
Evaluated relational algebra for predicate SqlAlchemy::SqlAlchemy::Connection::ConnectionConstruction#45e716e0@594cfx2g on iteration 4 running pipeline standard with tuple counts:
48722 ~6% {2} r1 = DataFlowPublic::CallCfgNode#b8ddbf81 AND NOT SqlAlchemy::SqlAlchemy::Connection::ConnectionConstruction#45e716e0#prev(FIRST 2)
48722 ~3% {3} r2 = SCAN r1 OUTPUT In.0, _, In.1
48722 ~1% {3} | REWRITE WITH Out.1 := "connect"
16 ~0% {3} | JOIN WITH `DataFlowPublic::MethodCallNode.calls/2#dispred#1dd1e0f4#ffb_021#join_rhs` ON FIRST 2 OUTPUT Rhs.2, Lhs.0, Lhs.2
0 ~0% {2} | JOIN WITH `SqlAlchemy::SqlAlchemy::Connection::instance/0#5ed87c17#prev_delta` ON FIRST 1 OUTPUT Lhs.1, Lhs.2
48722 ~3% {3} r3 = SCAN r1 OUTPUT In.0, _, In.1
48722 ~2% {3} | REWRITE WITH Out.1 := "execution_options"
9 ~0% {3} | JOIN WITH `DataFlowPublic::MethodCallNode.calls/2#dispred#1dd1e0f4#ffb_021#join_rhs` ON FIRST 2 OUTPUT Rhs.2, Lhs.0, Lhs.2
0 ~0% {2} | JOIN WITH `SqlAlchemy::SqlAlchemy::Connection::instance/0#5ed87c17#prev_delta` ON FIRST 1 OUTPUT Lhs.1, Lhs.2
0 ~0% {2} r4 = r2 UNION r3
return r4
```
which is fixed by `connectionConstruction_helper`
```
Evaluated recursive predicate SqlAlchemy::SqlAlchemy::Connection::helper/0#62cfc178#b@4f295yef in 1ms on iteration 4 (delta size: 0).
Evaluated relational algebra for predicate SqlAlchemy::SqlAlchemy::Connection::helper/0#62cfc178#b@4f295yef on iteration 4 running pipeline standard with tuple counts:
4 ~0% {1} r1 = JOIN `SqlAlchemy::SqlAlchemy::Connection::instance/1#029b4c87#prev_delta` WITH `TypeTrackingImpl::TypeTracker::end/0#2ac2cfd4` ON FIRST 1 OUTPUT Lhs.1
16 ~0% {1} | JOIN WITH `LocalSources::Cached::hasLocalSource/2#8b3ee0ec_10#join_rhs` ON FIRST 1 OUTPUT Rhs.1
0 ~0% {3} | JOIN WITH `DataFlowPublic::MethodCallNode.calls/2#dispred#1dd1e0f4#ffb_102#join_rhs` ON FIRST 1 OUTPUT Rhs.1, Rhs.2, _
0 ~0% {2} | REWRITE WITH NOT [NOT [Tmp.2 := "connect", TEST InOut.1 = Tmp.2], NOT [Tmp.2 := "execution_options", TEST InOut.1 = Tmp.2]] KEEPING 2
0 ~0% {1} | JOIN WITH DataFlowPublic::CallCfgNode#b8ddbf81 ON FIRST 1 OUTPUT Lhs.0
0 ~0% {1} | AND NOT `SqlAlchemy::SqlAlchemy::Connection::helper/0#62cfc178#b#prev`(FIRST 1)
return r1
```
We do this to remove the inconsistencies, and to be ready for a future
where type-tracking support content tracker of depth > 1.
It works because targets of loadSteps needs to be LocalSourceNodes
predicate loadStep(Node nodeFrom, LocalSourceNode nodeTo, Content content) {
(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()) }
```
