EWG supports:

-users verifying that this model meets their needs, particularly for pointer zap
-authors work with SG22 and WG14 to align C and C++ solutions
-implementation experience be obtained
-usage experience be obtained

then we want to see the paper again

Result: Consensus

Related: #895 #553 #1084 #1011

@NinaRanns: Should this issue get an update from the SG22 discussion?

probably :)
SG22 had a meeting to discuss the issue. WG14 felt the wording presented in P2434 doesn't solve the problem from WG14 perspective. The room didn't find a common way forward. Notes from the meeting can be found here

P2434R1 Nondeterministic pointer provenance (S. Davis Herring)

P2434r1 Nondeterministic pointer provenance: Expand the paper to specify the special angelic behavior on std::atomic<T*>.

Not consensus (too many neutrals).

P2434R1 Nondeterministic pointer provenance: forward to SG1/CWG/LEWG for inclusion in C++26.

Consensus.

CWG 2024-06-25: Brief discussion on differences between WG14 (superimposed pointer values) and WG21 (angelic nondeterminism) approaches. Provenance of integers (and erasure thereof with arithmetic) mentioned.

CWG 2024-06-27 in St. Louis: Reviewed; needs updates.

SG1 in St Louis

SG1 believes that the approach of P2434R1 can address
the zap problem with some additional (simpler) changes
e.g.:

1. Convenience / future-proofing in casts & atomics
2. Tightening invalid-pointer semantics
   SF F N A SA
   3 7 1 0 0
   Unanimous consent

CWG 2024-11-22 in Wroclaw: CWG found the following example from the paper a rather surprising consequence for optimizers, and asks EWG to affirm this consequence is expressly acknowledged:

void f(T* p) {
  T* t = new T();
  if (opaque_fn(t)) {
    // *t and *p can alias here
  }
}

(out of order)

2024-11-20 Library Evolution Wroclaw Meeting

P2434R2 Nondeterministic pointer provenance

2024-11-20 Library Evolution Wroclaw Meeting Minutes

Champion: Davis Herring
Chair: Inbal Levi / Fabio Fracassi
Minute Taker: Robert Leahy

Summary

POLL: Forward P2434R2 to LWG for C++26.

Attendance: 17 (IP) + 2(R)
Outcome: Outcome: No objection to unanimous consent

Next Steps

P2434R2 was forwarded to LWG for C++26.

P2434R3 Nondeterministic pointer provenance (S. Davis Herring)

P2434R3 Nondeterministic pointer provenance: EWG wants to split prospective pointer value out of P2434R3 and see that portion in EWG again.

Consensus.

@opensdh , I think we're still waiting for an update that manifests "EWG wants to split prospective pointer value out of P2434R3", right?

@opensdh , I think we're still waiting for an update that manifests "EWG wants to split prospective pointer value out of P2434R3", right?

Sort of: at the very end of the Hagenberg meeting I had an inspiration that replaces that requested edit with (hopefully) a better edit. I will certainly have that ready for the pre-Sofia mailing, because it's very little work.