{"id":2227723,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2227723/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/patch/20260424065244.262557-4-tkaminsk@redhat.com/","project":{"id":17,"url":"http://patchwork.ozlabs.org/api/1.1/projects/17/?format=json","name":"GNU Compiler Collection","link_name":"gcc","list_id":"gcc-patches.gcc.gnu.org","list_email":"gcc-patches@gcc.gnu.org","web_url":null,"scm_url":null,"webscm_url":null},"msgid":"<20260424065244.262557-4-tkaminsk@redhat.com>","date":"2026-04-24T06:41:11","name":"[v2,4/4] libstdc++: Make ref_view statically sized if R has static size","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"acfbe9adec051e86d70fbdfc62eec9b80ec1cfc5","submitter":{"id":90409,"url":"http://patchwork.ozlabs.org/api/1.1/people/90409/?format=json","name":"Tomasz Kamiński","email":"tkaminsk@redhat.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/gcc/patch/20260424065244.262557-4-tkaminsk@redhat.com/mbox/","series":[{"id":501310,"url":"http://patchwork.ozlabs.org/api/1.1/series/501310/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/list/?series=501310","date":"2026-04-24T06:41:08","name":"[v2,1/4] libstdc++: Merged concept for ranges with static sized.","version":2,"mbox":"http://patchwork.ozlabs.org/series/501310/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2227723/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2227723/checks/","tags":{},"headers":{"Return-Path":"","X-Original-To":["incoming@patchwork.ozlabs.org","gcc-patches@gcc.gnu.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","gcc-patches@gcc.gnu.org"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=mimecast20190719 header.b=JbvxjP5G;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org\n (client-ip=38.145.34.32; helo=vm01.sourceware.org;\n envelope-from=gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org;\n receiver=patchwork.ozlabs.org)","sourceware.org;\n\tdkim=pass (1024-bit key,\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=mimecast20190719 header.b=JbvxjP5G","sourceware.org; dmarc=pass (p=quarantine dis=none)\n header.from=redhat.com","sourceware.org; spf=pass smtp.mailfrom=redhat.com","server2.sourceware.org;\n arc=none smtp.remote-ip=170.10.133.124"],"Received":["from vm01.sourceware.org (vm01.sourceware.org [38.145.34.32])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519 server-signature ECDSA (secp384r1) server-digest SHA384)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4g23fm0CxNz1xvV\n\tfor ; Fri, 24 Apr 2026 16:57:04 +1000 (AEST)","from vm01.sourceware.org (localhost [127.0.0.1])\n\tby sourceware.org (Postfix) with ESMTP id 0F4A04BB24D5\n\tfor ; Fri, 24 Apr 2026 06:57:02 +0000 (GMT)","from us-smtp-delivery-124.mimecast.com\n (us-smtp-delivery-124.mimecast.com [170.10.133.124])\n by sourceware.org (Postfix) with ESMTP id 7375B4BB24D8\n for ; Fri, 24 Apr 2026 06:52:58 +0000 (GMT)","from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com\n (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by\n relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3,\n cipher=TLS_AES_256_GCM_SHA384) id us-mta-330-qwp3OcPbNI-61MWrsYSqnA-1; Fri,\n 24 Apr 2026 02:52:54 -0400","from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com\n (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111])\n (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest\n SHA256)\n (No client certificate requested)\n by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS\n id 24C7618005B1; Fri, 24 Apr 2026 06:52:53 +0000 (UTC)","from localhost (unknown [10.44.48.150])\n by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP\n id A27DE180047F; Fri, 24 Apr 2026 06:52:52 +0000 (UTC)"],"DKIM-Filter":["OpenDKIM Filter v2.11.0 sourceware.org 0F4A04BB24D5","OpenDKIM Filter v2.11.0 sourceware.org 7375B4BB24D8"],"DMARC-Filter":"OpenDMARC Filter v1.4.2 sourceware.org 7375B4BB24D8","ARC-Filter":"OpenARC Filter v1.0.0 sourceware.org 7375B4BB24D8","ARC-Seal":"i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1777013578; cv=none;\n b=NYEhOSReO90MbwNRAm61xJE60QhdgLxSCHMeKFm+k6gT9pVRT2GYzHsxOQ7yAxrxC4zJ2h14JAfMjwCQPjuGyzIt9yd72m+IleQr4Ix7P8wUiC5RT8iKBkPHDfsXVaMrk3bzbT4b9vX7WN0fbdX2/cfhsSn3Wy96HVGOXA3LA8o=","ARC-Message-Signature":"i=1; a=rsa-sha256; d=sourceware.org; s=key;\n t=1777013578; c=relaxed/simple;\n bh=iSowgv4XpGN4k3OWOkjgV0sF9sy8375QxolopR3UeC0=;\n h=DKIM-Signature:From:To:Subject:Date:Message-ID:MIME-Version;\n b=ckIgQow7pxDvksabTsbXBukSTbkMPJUEjgvs14shfSNMjdexu1UfpzvGnxGo9C9sTtAA89NdB+0umJU8lTkH/+sLV1Srgxyxot7VredIhLJkrSiaMalp2ycfV4OIIhoERlWlp2tQbLFui3Gwng5RFmJVpjgjOAhIsbV/gTe/MIU=","ARC-Authentication-Results":"i=1; server2.sourceware.org","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com;\n s=mimecast20190719; t=1777013578;\n h=from:from:reply-to:subject:subject:date:date:message-id:message-id:\n to:to:cc:mime-version:mime-version:content-type:content-type:\n content-transfer-encoding:content-transfer-encoding:\n in-reply-to:in-reply-to:references:references;\n bh=tHCYqDlfAHN0yv50/ZQ7chlIWxFN/5QDfQFLFcadQgg=;\n b=JbvxjP5GjFkd3UfsGh2nmmCtcPDhjAo+p9Wox2WTDzPiRh1NwBOwQnzAI/KtIHAJM9byik\n pxcFgrD94t0ypxGAZCZ8zT6MlUMvSQiQVZ/xZ2Vv3soxMWvQIJqN34F3tZmkX86UPCN9qN\n GdcxCn70sEp39p+jNfuBeS636q4Wd5k=","X-MC-Unique":"qwp3OcPbNI-61MWrsYSqnA-1","X-Mimecast-MFC-AGG-ID":"qwp3OcPbNI-61MWrsYSqnA_1777013573","From":"=?utf-8?q?Tomasz_Kami=C5=84ski?= ","To":"libstdc++@gcc.gnu.org,\n\tgcc-patches@gcc.gnu.org","Subject":"[PATCH v2 4/4] libstdc++: Make ref_view statically sized if R has\n static size","Date":"Fri, 24 Apr 2026 08:41:11 +0200","Message-ID":"<20260424065244.262557-4-tkaminsk@redhat.com>","In-Reply-To":"<20260424065244.262557-1-tkaminsk@redhat.com>","References":"\n \n <20260424065244.262557-1-tkaminsk@redhat.com>","MIME-Version":"1.0","X-Scanned-By":"MIMEDefang 3.4.1 on 10.30.177.111","X-Mimecast-Spam-Score":"0","X-Mimecast-MFC-PROC-ID":"U5QePfIOrCAQMJeZdQK75alaDsGKwW8A_Jta5wzf9hs_1777013573","X-Mimecast-Originator":"redhat.com","Content-Transfer-Encoding":"8bit","content-type":"text/plain; charset=\"US-ASCII\"; x-default=true","X-BeenThere":"gcc-patches@gcc.gnu.org","X-Mailman-Version":"2.1.30","Precedence":"list","List-Id":"Gcc-patches mailing list ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org"},"content":"This patch introduces ranges::__static_size<_Range> helper functions,\nthat returns ranges::size(__rg) for __statically_sized_range.\nThis function is then used for ref_view::size if R has static size,\navoiding derefence of pointer value that is not know at compile time.\nSimilary for ref_view::empty() we compare the size with zero,\nif it is know statically.\n\nThis implements revelant part of P3928R0: static_sized_range by Hewill Kang.\nAs standard does not specify when constexpr functions are usable at compile\ntime, such implementation are allowed (but not mandated) by current draft.\n\nlibstdc++-v3/ChangeLog:\n\n\t* include/bits/ranges_base.h (ranges::__static_size): Define.\n\t* include/std/ranges (ref_view::size()): For ranges with static\n\tsize return ranges::__static_size<_Range> == 0.\n\t(ref_view::empty): For ranges with static size, compare it\n\tagainst zero.\n\t* testsuite/23_containers/inplace_vector/cons/from_iota_neg.cc:\n\tExpect errors from ref_view uses.\n\t* testsuite/23_containers/inplace_vector/cons/from_range_neg.cc:\n\tExpect errors from ref_view uses.\n---\nv2 also expands the empty() method, and adds __static_size helper funciton.\nWe could really use some consteval __builtin_unknown_ref(_Tp), that will\nproduce reference to unknown object of type _Tp. This will avoid nested\nlambda and instantiating integer_constant.\n\nTested on x86_64-linux. OK for trunk?\n\n libstdc++-v3/include/bits/ranges_base.h | 9 +++++++++\n libstdc++-v3/include/std/ranges | 18 ++++++++++++++++--\n .../inplace_vector/cons/from_iota_neg.cc | 6 ++----\n .../inplace_vector/cons/from_range_neg.cc | 10 ++++------\n 4 files changed, 31 insertions(+), 12 deletions(-)","diff":"diff --git a/libstdc++-v3/include/bits/ranges_base.h b/libstdc++-v3/include/bits/ranges_base.h\nindex fea4100eb09..e61ef75f857 100644\n--- a/libstdc++-v3/include/bits/ranges_base.h\n+++ b/libstdc++-v3/include/bits/ranges_base.h\n@@ -562,6 +562,15 @@ namespace ranges\n template\n concept __static_sized_range = sized_range<_Tp> && requires (_Tp& __t)\n { static_cast= 0)]>(nullptr); };\n+\n+ template<__static_sized_range _Tp>\n+ consteval range_size_t<_Tp>\n+ __static_size()\n+ {\n+ auto __conjure = [](_Tp& __t)\n+ { return integral_constant, ranges::size(__t)>{}; };\n+ return decltype(__conjure(std::declval<_Tp&>()))::value;\n+ }\n #endif // C++26\n \n template\ndiff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges\nindex 4f2082487d1..c1e8ac3cb17 100644\n--- a/libstdc++-v3/include/std/ranges\n+++ b/libstdc++-v3/include/std/ranges\n@@ -1380,11 +1380,25 @@ namespace views::__adaptor\n \n constexpr bool\n empty() const requires requires { ranges::empty(*_M_r); }\n- { return ranges::empty(*_M_r); }\n+ {\n+#if __cplusplus > 202302L\n+\tif constexpr (__static_sized_range<_Range>)\n+\t return ranges::__static_size<_Range>() == 0;\n+ else\n+#endif\n+\t return ranges::empty(*_M_r);\n+ }\n \n constexpr auto\n size() const requires sized_range<_Range>\n- { return ranges::size(*_M_r); }\n+ {\n+#if __cplusplus > 202302L\n+\tif constexpr (__static_sized_range<_Range>)\n+\t return ranges::__static_size<_Range>();\n+ else\n+#endif\n+\t return ranges::size(*_M_r);\n+ }\n \n constexpr auto\n data() const requires contiguous_range<_Range>\ndiff --git a/libstdc++-v3/testsuite/23_containers/inplace_vector/cons/from_iota_neg.cc b/libstdc++-v3/testsuite/23_containers/inplace_vector/cons/from_iota_neg.cc\nindex ae0b96175b7..6b66b5d97ed 100644\n--- a/libstdc++-v3/testsuite/23_containers/inplace_vector/cons/from_iota_neg.cc\n+++ b/libstdc++-v3/testsuite/23_containers/inplace_vector/cons/from_iota_neg.cc\n@@ -33,14 +33,12 @@ test_all()\n std::inplace_vector tr1(std::from_range, ref_view(m12));\n \n std::inplace_vector tm2(std::from_range, m12); // { dg-error \"(from here|expansion of)\" }\n- // ref_view is not statically sized due pointer dereference\n- std::inplace_vector tr2(std::from_range, ref_view(m12));\n+ std::inplace_vector tr2(std::from_range, ref_view(m12)); // { dg-error \"(from here|expansion of)\" }\n \n StaticIota<__int128, 0> mm;\n \n std::inplace_vector tm3(std::from_range, mm); // { dg-error \"(from here|expansion of)\" }\n- // ref_view is not statically sized due pointer dereference\n- std::inplace_vector tr3(std::from_range, ref_view(mm));\n+ std::inplace_vector tr3(std::from_range, ref_view(mm)); // { dg-error \"(from here|expansion of)\" }\n }\n \n // { dg-error \"static assertion failed\" \"\" { target *-*-* } 0 }\ndiff --git a/libstdc++-v3/testsuite/23_containers/inplace_vector/cons/from_range_neg.cc b/libstdc++-v3/testsuite/23_containers/inplace_vector/cons/from_range_neg.cc\nindex 48d5b4c56f5..ea187761e5e 100644\n--- a/libstdc++-v3/testsuite/23_containers/inplace_vector/cons/from_range_neg.cc\n+++ b/libstdc++-v3/testsuite/23_containers/inplace_vector/cons/from_range_neg.cc\n@@ -62,16 +62,14 @@ test_all()\n \n test_one(a1); // { dg-error \"from here\" }\n test_one(s1); // { dg-error \"from here\" }\n- // ref_view is not statically sized due pointer dereference\n- test_one(ref_view(a1));\n- test_one(a5 | std::views::adjacent<7> | std::views::elements<0>);\n+ test_one(ref_view(a1)); // { dg-error \"from here\" }\n+ test_one(a5 | std::views::adjacent<5> | std::views::elements<0>); // { dg-error \"from here\" }\n test_one(s5 | std::views::adjacent<5> | std::views::elements<0>); // { dg-error \"from here\" }\n \n test_five(a5); // { dg-error \"from here\" }\n test_five(s5); // { dg-error \"from here\" }\n- // ref_view is not statically sized due pointer dereference\n- test_five(ref_view(a5));\n- test_five(a7 | std::views::adjacent<3> | std::views::elements<0>);\n+ test_five(ref_view(a5)); // { dg-error \"from here\" }\n+ test_five(a7 | std::views::adjacent<3> | std::views::elements<0>); // { dg-error \"from here\" }\n test_five(s7 | std::views::adjacent<3> | std::views::elements<0>); // { dg-error \"from here\" }\n }\n \n","prefixes":["v2","4/4"]}