The issue is:
lib/src/logger.html, line 107, inserted !:
In this case the single reason detail reads "node with no info (type(2171))" with no destination.
The problem is that InstrumentationInformation.nodeInfoFor is only
considering a limited set of possible sources of nullability nodes
(the primary nodes of decorated types passed to the instrumentation
listener methods `implicitReturnType`, `implicitType`, and
`implicitTypeArguments`). It needs to also consider decorated types
passed to `explicitTypeNullability`, `externalDecoratedType`, and
`externalDecoratedTypeParameterBound`, and it needs to walk these
decorated types recursively to discover all the nodes they point to.
Additionally, the logic in InstrumentationInformation.nodeInfoFor is
inefficient; it walks through all the implicit types in every source
file, which means that it is O(N) in the size of the code being
migrated. Since it is called O(N) times, this is an overall runtime
complexity of O(N^2).
I've prototyped a possible fix using an expando to compute
NodeInformation for each node once at the time it's reported to
instrumentation. This is incomplete and intended as a starting point
for discussion. Work that still needs to be done:
- We don't produce a sensible description string for nullability nodes
associated with AST nodes, so we present unhelpful text to the user
like "A nullable value can't be used as the explicit type ???"; it
would be nicer to say something like "A nullable value can't be used
as positional argument 0 of Level.>=". We may want to consider
modifying the instrumentation API to make it easier to generate a
useful string here.
- I haven't verified that the description string we produce for
external decorated types is helpful.
- I haven't verified that the we produce a useful link for external
decorated types.
- We should probably get rid of the data structure
NodeInformation.explicitTypeNullability (which has similar
inefficiencies) and change over code that was using it to use the
new approach.
Change-Id: I2cf2fe47cd70d7e5cc6e3da309851288668e8a62
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/124902
Commit-Queue: Paul Berry <paulberry@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Paul Berry
12265c4e42