From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: Tom Honermann <tom@honermann.net>,
Florian Weimer <fweimer@redhat.com>,
Adhemerval Zanella via Libc-alpha <libc-alpha@sourceware.org>
Cc: Joseph Myers <joseph@codesourcery.com>
Subject: Re: [PATCH 2/3]: C++20 P0482R6 and C2X N2653: Implement mbrtoc8, c8rtomb, char8_t
Date: Wed, 18 May 2022 13:17:37 -0300 [thread overview]
Message-ID: <6b3dd2a0-80b9-a1bd-b157-c6f92cdf7fb2@linaro.org> (raw)
In-Reply-To: <af6b0cd3-ecea-3e24-ea79-b9214dba9fe7@honermann.net>
On 18/05/2022 12:32, Tom Honermann wrote:
> On 5/17/22 5:33 PM, Florian Weimer wrote:
>> * Adhemerval Zanella via Libc-alpha:
>>
>>> On 17/05/2022 15:12, Joseph Myers wrote:
>>>> On Tue, 17 May 2022, Adhemerval Zanella wrote:
>>>>
>>>>>> +/* This is the private state used if PS is NULL. */
>>>>>> +static mbstate_t state;
>>>>> Although it was done for other convertion interfaces, I wonder if we should
>>>>> keep supporting this mt-unsafe usage for newer ones. It was not clear from
>>>> In C23 it's implementation-defined whether the internal state for such
>>>> functions has static or thread storage duration (see the general
>>>> introduction to the uchar.h functions).
>>>>
>>> Right, so glibc still need to support either mode.
>> No, I think we can and should switch. Maybe with new symbol versions
>> (but the same implementation) if we want to play it conservative.
>>
>> The intent in POSIX and C has been for a long time that thread-local
>> state is permitted for these functions, only the wording did not
>> technically allow it. The phrase was “not required to avoid data
>> races”. The problem is that it's possible to tell the difference
>> without data races (with external synchronization). Many libcs already
>> use thread-local state for these functions, without any apparent ill
>> effects.
>
> I would err on the side of maintaining consistency across these functions for now and then transition them all at once if there is a desire to do so.
Do we need to keep distinct states for each one or can use the a shared
one?
next prev parent reply other threads:[~2022-05-18 16:17 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-27 16:53 Tom Honermann
2022-02-28 23:01 ` Joseph Myers
2022-03-01 3:40 ` Tom Honermann
2022-05-17 15:57 ` Carlos O'Donell
2022-05-17 18:05 ` Adhemerval Zanella
2022-05-17 18:12 ` Joseph Myers
2022-05-17 18:17 ` Adhemerval Zanella
2022-05-17 21:33 ` Florian Weimer
2022-05-18 15:32 ` Tom Honermann
2022-05-18 16:17 ` Adhemerval Zanella [this message]
2022-05-18 17:26 ` Tom Honermann
2022-05-18 17:39 ` Adhemerval Zanella
2022-05-18 17:40 ` Florian Weimer
2022-05-18 17:57 ` Adhemerval Zanella
-- strict thread matches above, loose matches on Subject: below --
2022-01-08 0:39 Tom Honermann
2022-01-11 0:53 ` Joseph Myers
2022-01-11 19:23 ` Tom Honermann
2022-01-20 23:17 ` Tom Honermann
2022-01-21 20:01 ` Adhemerval Zanella
2022-01-22 12:24 ` Tom Honermann
2022-02-16 18:29 ` Joseph Myers
2022-02-16 19:14 ` tom
2021-06-07 2:08 Tom Honermann
2021-06-07 18:53 ` Joseph Myers
2021-06-11 11:25 ` Tom Honermann
2021-06-11 16:28 ` Joseph Myers
2021-06-13 15:35 ` Tom Honermann
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