On 2/19/19 12:03 PM, Jakub Jelinek wrote:
On Tue, Feb 19, 2019 at 11:28:22AM -1000, Jason Merrill wrote:
On Tue, Feb 19, 2019 at 4:00 AM Jakub Jelinek <ja...@redhat.com> wrote:
On Mon, Feb 18, 2019 at 03:01:14PM -1000, Jason Merrill wrote:
But it's not clear to me that the standard actually allows this. I don't
think changing the active member of a union in the mem-initializer for
another member is reasonable.
There is in [expr.const]/2:
an lvalue-to-rvalue conversion (7.1) that is applied to a glvalue that refers
to a non-active member of a
union or a subobject thereof;
an assignment expression (8.18) or invocation of an assignment operator (15.8)
that would change the
active member of a union;
in C++17 it seems, so maybe my union testcases are accepts-invalid.
This has been introduced in P0137R1 and removed again in P1330R0. Does that
mean e.g. following is valid in C++14, invalid in C++17 and valid again in
C++20? Or has one of the above papers changed retroactively previous
standards?
Before P0137 I believe foo and bar were arguably undefined.
I see, before that it was:
"an lvalue-to-rvalue conversion (4.1) or modification (5.18, 5.2.6, 5.3.2) that
is applied
to a glvalue that refers to a non-active member of a union or a subobject
thereof;"
So, do we want something like this then (or free all vectors immediately
there and return immediately)?
2019-02-19 Jakub Jelinek <ja...@redhat.com>
PR c++/89336
* constexpr.c (cxx_eval_store_expression): Diagnose changing of active
union member for -std=c++17 and earlier.
OK. I don't think it's important to return immediately.
Jason
