From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp-out2.suse.de (smtp-out2.suse.de [IPv6:2001:67c:2178:6::1d]) by sourceware.org (Postfix) with ESMTPS id F2FB03858C78 for ; Fri, 29 Sep 2023 12:40:10 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org F2FB03858C78 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=suse.de Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=suse.de Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 282431F74B; Fri, 29 Sep 2023 12:40:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1695991210; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=9aoPmbFJTDG7RdHcBAAJokkBojOKdeEJ6K2v4mPU518=; b=Jrp6XPxitw5iI7XZRbo8k8TWZgpu1fddaFauJgMozgA8Ik27Cd+1md7ip5OR8J3eqhfXgI yUfrMO9AAnZppAtibXNmTAt7lhGdUS2oguL42PzODzXW2tWRX/LUBAg0feb+57T6hfAu+9 bhlXJt4224kyirUwAtemu2bwxrJcELc= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1695991210; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=9aoPmbFJTDG7RdHcBAAJokkBojOKdeEJ6K2v4mPU518=; b=LZCHCa7gNAPf9oOup0fWsCfcu2MzQSbAQi7pUSYHv/Zem0VHduf+ZkCDVqaMNAktytyWH2 34Oo4uWaaYC0oNDg== Received: from wotan.suse.de (wotan.suse.de [10.160.0.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 08F252C143; Fri, 29 Sep 2023 12:40:10 +0000 (UTC) Date: Fri, 29 Sep 2023 12:40:10 +0000 (UTC) From: Richard Biener To: Jakub Jelinek cc: Jonathan Wakely , gcc-patches@gcc.gnu.org Subject: Re: [PATCH] vec.h: Guard most of static assertions for GCC >= 5 In-Reply-To: Message-ID: References: User-Agent: Alpine 2.22 (LSU 394 2020-01-19) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Spam-Status: No, score=-4.8 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,KAM_NUMSUBJECT,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Fri, 29 Sep 2023, Jakub Jelinek wrote: > Hi! > > As reported by Jonathan on IRC, my vec.h patch broke build with GCC 4.8.x > or 4.9.x as system compiler, e.g. on CFarm. > The problem is that while all of > std::is_trivially_{destructible,copyable,default_constructible} traits > are in C++, only std::is_trivially_destructible has been implemented in GCC > 4.8, the latter two were added only in GCC 5. > Only std::is_trivially_destructible is the really important one though, > which is used to decide what pop returns and whether to invoke the > destructors or not. The rest are solely used in static_asserts and as such > I think it is acceptable if we don't assert those when built with GCC 4.8 > or 4.9, anybody doing bootstrap from those system compilers or doing builds > with newer GCC will catch that. > > So, the following patch guards those for 5+. > If we switch to C++14 later on and start requiring newer version of system > GCC as well (do we require GCC >= 5 which claims the last C++14 language > features, or what provides all C++14 library features, or GCC >= 6 which > uses -std=c++14 by default?), this patch then can be reverted. I'd say we can recommend a compiler with all language and library features but "support" the oldest working compiler. For us it's practically GCC 4.8 (doesn't work) or GCC 7 (new enough anyway). > Ok for trunk? OK. Richard. > 2023-09-29 Jakub Jelinek > > * vec.h (quick_insert, ordered_remove, unordered_remove, > block_remove, qsort, sort, stablesort, quick_grow): Guard > std::is_trivially_{copyable,default_constructible} and > vec_detail::is_trivially_copyable_or_pair static assertions > with GCC_VERSION >= 5000. > (vec_detail::is_trivially_copyable_or_pair): Guard definition > with GCC_VERSION >= 5000. > > --- gcc/vec.h.jj 2023-09-29 10:59:09.830551963 +0200 > +++ gcc/vec.h 2023-09-29 12:29:32.676428677 +0200 > @@ -1086,7 +1086,12 @@ vec::quick_insert (unsig > { > gcc_checking_assert (length () < allocated ()); > gcc_checking_assert (ix <= length ()); > +#if GCC_VERSION >= 5000 > + /* GCC 4.8 and 4.9 only implement std::is_trivially_destructible, > + but not std::is_trivially_copyable nor > + std::is_trivially_default_constructible. */ > static_assert (std::is_trivially_copyable ::value, ""); > +#endif > T *slot = &address ()[ix]; > memmove (slot + 1, slot, (m_vecpfx.m_num++ - ix) * sizeof (T)); > *slot = obj; > @@ -1102,7 +1107,9 @@ inline void > vec::ordered_remove (unsigned ix) > { > gcc_checking_assert (ix < length ()); > +#if GCC_VERSION >= 5000 > static_assert (std::is_trivially_copyable ::value, ""); > +#endif > T *slot = &address ()[ix]; > memmove (slot, slot + 1, (--m_vecpfx.m_num - ix) * sizeof (T)); > } > @@ -1150,7 +1157,9 @@ inline void > vec::unordered_remove (unsigned ix) > { > gcc_checking_assert (ix < length ()); > +#if GCC_VERSION >= 5000 > static_assert (std::is_trivially_copyable ::value, ""); > +#endif > T *p = address (); > p[ix] = p[--m_vecpfx.m_num]; > } > @@ -1164,13 +1173,16 @@ inline void > vec::block_remove (unsigned ix, unsigned len) > { > gcc_checking_assert (ix + len <= length ()); > +#if GCC_VERSION >= 5000 > static_assert (std::is_trivially_copyable ::value, ""); > +#endif > T *slot = &address ()[ix]; > m_vecpfx.m_num -= len; > memmove (slot, slot + len, (m_vecpfx.m_num - ix) * sizeof (T)); > } > > > +#if GCC_VERSION >= 5000 > namespace vec_detail > { > /* gcc_{qsort,qsort_r,stablesort_r} implementation under the hood > @@ -1189,6 +1201,7 @@ namespace vec_detail > : std::integral_constant::value > && std::is_trivially_copyable::value> { }; > } > +#endif > > /* Sort the contents of this vector with qsort. CMP is the comparison > function to pass to qsort. */ > @@ -1197,7 +1210,9 @@ template > inline void > vec::qsort (int (*cmp) (const void *, const void *)) > { > +#if GCC_VERSION >= 5000 > static_assert (vec_detail::is_trivially_copyable_or_pair ::value, ""); > +#endif > if (length () > 1) > gcc_qsort (address (), length (), sizeof (T), cmp); > } > @@ -1210,7 +1225,9 @@ inline void > vec::sort (int (*cmp) (const void *, const void *, void *), > void *data) > { > +#if GCC_VERSION >= 5000 > static_assert (vec_detail::is_trivially_copyable_or_pair ::value, ""); > +#endif > if (length () > 1) > gcc_sort_r (address (), length (), sizeof (T), cmp, data); > } > @@ -1223,7 +1240,9 @@ inline void > vec::stablesort (int (*cmp) (const void *, const void *, > void *), void *data) > { > +#if GCC_VERSION >= 5000 > static_assert (vec_detail::is_trivially_copyable_or_pair ::value, ""); > +#endif > if (length () > 1) > gcc_stablesort_r (address (), length (), sizeof (T), cmp, data); > } > @@ -1396,7 +1415,9 @@ inline void > vec::quick_grow (unsigned len) > { > gcc_checking_assert (length () <= len && len <= m_vecpfx.m_alloc); > +#if GCC_VERSION >= 5000 > // static_assert (std::is_trivially_default_constructible ::value, ""); > +#endif > m_vecpfx.m_num = len; > } > > > Jakub > > -- Richard Biener SUSE Software Solutions Germany GmbH, Frankenstrasse 146, 90461 Nuernberg, Germany; GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)