DynamicValues are generated whenever a partially evaluated expression is
unable to be resolved statically. They contain a reference to the ts.Node
which wasn't resolvable.
They can also be nested. For example, the expression 'a + b' is resolvable
only if 'a' and 'b' are themselves resolvable. If either 'a' or 'b' resolve
to a DynamicValue, the whole expression must also resolve to a DynamicValue.
Previously, if 'a' resolved to a DynamicValue, the entire expression might
have been resolved to the same DynamicValue. This correctly indicated that
the expression wasn't resolvable, but didn't return a reference to the
shallow node that couldn't be resolved (the expression 'a + b'), only a
reference to the deep node that couldn't be resolved ('a').
In certain situations, it's very useful to know the shallow unresolvable
node (for example, to use it verbatim in the output). To support this,
the partial evaluator is updated to always wrap DynamicValue to point to
each unresolvable expression as it's processed, ensuring the receiver can
determine exactly which expression node failed to resolve.
PR Close#29033
a23a0bc3a4