CWG 2024-11-08

If "modifications [...] occur in some particular total order", one can equivalently define a strict or non-strict total order over them, as those are isomorphic. Phrases like "A is earlier than B in the modification order of M" plainly refer to <, not <=.

Additional notes (November, 2024)

Forwarded to SG1 and LWG by decision of the CWG chair, via paper issue 2137.

Suggested resolution:

1. Change in 6.9.2.2 [intro.races] paragraph 4 as follows:

   All modifications to a particular atomic object M occur in some particular strict total order, called the modification order of M. ...

2. Change in 32.5.4 [atomics.order] paragraph 4 as follows:

   There is a single strict total order S on all memory_order::seq_cst operations, including fences, that satisfies the following constraints. ...

(From submission #636.)

Subclause 6.9.2.2 [intro.races] paragraph 4 specifies:

All modifications to a particular atomic object M occur in some particular total order, called the modification order of M. ...

Is the total order a strict total order? If not, modifications may appear to occur simultaneously.