From: Jonathan Wakely <jwakely@redhat.com>
To: Patrick Palka <ppalka@redhat.com>
Cc: gcc Patches <gcc-patches@gcc.gnu.org>,
"libstdc++" <libstdc++@gcc.gnu.org>
Subject: Re: [PATCH] libstdc++: Work around modules ICE in <charconv> [PR105297]
Date: Thu, 21 Apr 2022 09:41:51 +0100 [thread overview]
Message-ID: <CACb0b4mBxwUgwViS4fgzXUuCfFO5HLD1SmsVsigWEof+5T8-aw@mail.gmail.com> (raw)
In-Reply-To: <20220421033743.1297740-1-ppalka@redhat.com>
On Thu, 21 Apr 2022 at 04:38, Patrick Palka via Libstdc++
<libstdc++@gcc.gnu.org> wrote:
>
> This makes the initializer for __table in __from_chars_alnum_to_val
> dependent in an artificial way, which works around the modules testsuite
> ICE reported in PR105297 by preventing the initializer from getting
> evaluated at parse time.
>
> Compared to the alternative workaround of using a non-local class type
> for __table, this workaround has the advantage of slightly speeding up
> compilation of the <charconv> header, since now the table will not get
> built (via constexpr evaluation) until one of the integer std::from_chars
> overloads is actually instantiated.
>
> Tested on x86_64-pc-linux-gnu, does this look OK for trunk?
OK, thanks.
>
> PR c++/105297
> PR c++/105322
>
> libstdc++-v3/ChangeLog:
>
> * include/std/charconv (__from_chars_alnum_to_val): Make
> initializer for __table dependent in an artificial way.
> ---
> libstdc++-v3/include/std/charconv | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/libstdc++-v3/include/std/charconv b/libstdc++-v3/include/std/charconv
> index f1ace406017..561234cb2fc 100644
> --- a/libstdc++-v3/include/std/charconv
> +++ b/libstdc++-v3/include/std/charconv
> @@ -445,7 +445,9 @@ namespace __detail
> return __c - '0';
> else
> {
> - static constexpr auto __table = __from_chars_alnum_to_val_table();
> + // This initializer is deliberately made dependent in order to work
> + // around modules bug PR105322.
> + static constexpr auto __table = (_DecOnly, __from_chars_alnum_to_val_table());
> return __table.__data[__c];
> }
> }
> --
> 2.36.0.rc2.10.g1ac7422e39
>
prev parent reply other threads:[~2022-04-21 8:42 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-21 3:37 Patrick Palka
2022-04-21 8:41 ` Jonathan Wakely [this message]
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