C++: Fix small PrintAST and PrintIR issue

[jketema]

• PrintIR is currently doing the wrong thing for OverloadedArrayExpr add a test and fix
• PrintIR currently does the wrong thing if a block has two outgoing edges to the same successor block. At present this is not an issue, but it will be once Brodes/seh flow phas3.1 add basic seh edges #18253 is merged. I tested this on top of that PR, but since merging that PR is somewhat blocked at present, I would like to get this in preemptively.

Pull Request checklist

All query authors

• A change note is added if necessary. See the documentation in this repository.
• All new queries have appropriate .qhelp. See the documentation in this repository.
• QL tests are added if necessary. See Testing custom queries in the GitHub documentation.
• New and changed queries have correct query metadata. See the documentation in this repository.

Internal query authors only

• Autofixes generated based on these changes are valid, only needed if this PR makes significant changes to .ql, .qll, or .qhelp files. See the documentation (internal access required).
• Changes are validated at scale (internal access required).
• Adding a new query? Consider also adding the query to autofix.

[Copilot]

Copilot encountered an error and was unable to review this pull request. You can try again, by re-requesting a review.

[MathiasVP]

If this is changed to a strictcount you could remove line 428, right?

[jketema]

I still need 428 to correctly bind succBlock in the other side of the or, I think.

[MathiasVP]

In the key = "semmle.order" case? That's bound by getSuccessorIndex anyway. Although, I do see that you need to rewrite the exists slightly to get rid of the resulting cartesian product with kind.

[jketema]

In the key = "semmle.order" case? That's bound by getSuccessorIndex anyway.

Ah, you're right.

So are you thinking of something like:

query predicate edges(PrintableIRBlock pred, PrintableIRBlock succ, string key, string value) {
  exists(IRBlock predBlock, IRBlock succBlock |
    predBlock = pred.getBlock() and
    succBlock = succ.getBlock() and
    (
      key = "semmle.label" and
      exists(string kinds |
        kinds =
          strictconcat(EdgeKind k |
            predBlock.getSuccessor(k) = succBlock
          |
            k.toString(), "|" order by k.toString()
          )
      |
        if predBlock.getBackEdgeSuccessor(_) = succBlock
        then value = kinds + " (back edge)"
        else value = kinds
      )
      or
      key = "semmle.order" and
      value = getSuccessorIndex(predBlock, succBlock).toString()
    )
  )
}

[MathiasVP]

Exactly 👍

[jketema]

Done in f9bfd96

[MathiasVP]

LGTM! The CI failures looks unrelated!