Fix TypeMerging bug with indirectly reachable public types (#7031)

TypeMerging works by representing the type definition graph as a
partitioned DFA and then refining the partitions to find mergeable
types. #7023 was due to a bug where the DFA included edges from public
types to their children, but did not necessarily include corresponding
states for those children.

One way to fix the bug would have been to traverse the type graph,
finding all reachable public types and creating DFA states for them, but
that might be expensive in cases where there are large graphs of public
types.

Instead, fix the problem by removing the edges from public types to
their children entirely. Types reachable from public types are also
public and therefore are not eligible to be merged, so these edges were
never necessary for correctness.

Fixes #7023.

0 files changed, 0 insertions, 0 deletions