Seems I've missed one thing, as the first hunk in
https://github.com/cplusplus/draft/commit/c8e68ed202b4a9260616bcee8a9768b5dca4bbca
changes the wording so that only potentially-evaluated id-expressions that
denote immediate functions must appear only in the specified contexts.
That IMO means that in unevaluated contexts there aren't such restrictions
anymore, so I think in unevaluated contexts one should be able to take the
address of an immediate function.
2020-02-28 Jakub Jelinek <jakub@redhat.com>
P1937R2 - Fixing inconsistencies between const{expr,eval} functions
* typeck.c (cp_build_addr_expr_1): Allow taking address of immediate
functions in unevaluated contexts.
* g++.dg/cpp2a/consteval3.C: Change dg-error about taking address of
immediate function in unevaluated contexts into dg-bogus.
* g++.dg/cpp2a/consteval16.C: New test.
