On Thu, Feb 08, 2024 at 04:40:40PM +0100, Hans-Peter Nilsson wrote:
> > Date: Wed, 7 Feb 2024 21:11:59 -0500
> > From: Marek Polacek <pola...@redhat.com>
>
> > On Wed, Feb 07, 2024 at 04:32:57PM -0500, Jason Merrill wrote:
> > > On 2/6/24 19:23, Hans-Peter Nilsson wrote:
> > > > > Date: Mon, 22 Jan 2024 14:33:59 -0500
> > > > > From: Marek Polacek <pola...@redhat.com>
> > > >
> > > > > On Mon, Jan 22, 2024 at 06:02:32PM +0100, Hans-Peter Nilsson wrote:
> > > > > > I don't really know whether this is the right way to treat
> > > > > > CONVERT_EXPR as below, but... Regtested native
> > > > > > x86_64-linux-gnu. Ok to commit?
> > > > >
> > > > > Thanks for taking a look at this problem.
> > > >
> > > > Thanks for the initial review.
>
> > > Incidentally, these testcases seem to require C++14; you can't have a
> > > switch
> > > in a constexpr function in C++11.
> > >
> > > Jason
> >
> > > diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
> > > index 2ebb1470dd5..fa346fe01c9 100644
> > > --- a/gcc/cp/constexpr.cc
> > > +++ b/gcc/cp/constexpr.cc
> > > @@ -7106,6 +7106,16 @@ cxx_eval_switch_expr (const constexpr_ctx *ctx,
> > > tree t,
> > > cond = cxx_eval_constant_expression (ctx, cond, vc_prvalue,
> > > non_constant_p, overflow_p);
> > > VERIFY_CONSTANT (cond);
> > > + if (TREE_CODE (cond) != INTEGER_CST)
> > > + {
> > > + /* If the condition doesn't reduce to an INTEGER_CST it isn't a
> > > usable
> > > + switch condition even if it's constant enough for other things
> > > + (c++/113545). */
> > > + gcc_checking_assert (ctx->quiet);
> > > + *non_constant_p = true;
> > > + return t;
> > > + }
> > > +
> > > *jump_target = cond;
> > >
> > > tree body
> >
> > The patch makes sense to me, although I'm afraid that losing the
> > REINTERPRET_CAST_P flag will cause other issues.
> >
> > HP, sorry that I never got back to you. I would be more than happy to
> > take the patch above, add some tests and test/bootstrap it, unless you
> > want to do that yourself.
> >
> > Thanks & sorry again,
>
> No worries, feel very welcome to deal with handling the
> actual fix. Also, you're better prepared than me, when it
> comes to dealing with any possible fallout. :)
>
> I'll send an updated version of the test-cases, moving them
> to the C++14 test directory (cpp1y, right?) and qualify them
> as c++14 instead, as Jason pointed out.
Right, cpp1y is c++14. Note that we wouldn't push the tests separately
to the patch itself, unless it's something that already works. Thanks,
Marek
