Previously, we used the offset of an AST node as a unique ID to
represent it, with a special hack to make sure we can distinguish a
generic function type from its return type (which has the same
offset). But in an upcoming CL, I will need to start associating
unique IDs with expressions, so that will bring up a whole bunch more
ambiguity.
This CL switches to a technique where we combine the offset and the
end of any source span into a single unique identifier. The algorithm
produces an output that is no larger than the square of either input.
Since we have 64-bit integers in Dart, this should be adequate for any
reasonable input file size.
Change-Id: I68ce27533eb485cc824e1080326d02de98bff1e7
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/132404
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Paul Berry