[{"id":3677380,"web_url":"http://patchwork.ozlabs.org/comment/3677380/","msgid":"<1cd5c843-fb51-407d-843c-21fe2c37e015@redhat.com>","list_archive_url":null,"date":"2026-04-14T19:58:55","subject":"Re: [PATCH] c++: Mark in cxx_mark_addressable DECL_VALUE_EXPR of\n DECL_ANON_UNION_VAR_P too [PR124850]","submitter":{"id":4337,"url":"http://patchwork.ozlabs.org/api/people/4337/","name":"Jason Merrill","email":"jason@redhat.com"},"content":"On 4/14/26 2:54 AM, Jakub Jelinek wrote:\n> Hi!\n> \n> The following testcase ICEs since my PR53932 change in checking,\n> because it sees address of the unnamed anon union VAR_DECL taken\n> but without having TREE_ADDRESSABLE set.\n> \n> The following patch sets it during cxx_mark_addressable. I'm wondering\n> how we can get away with not marking other DECL_VALUE_EXPR cases,\n> but couldn't come up with a testcase where it would be needed (e.g. for\n> structured bindings, etc.). So just doing it for anon union vars seems\n> safer to me at least for now.\n> \n> Bootstrapped/regtrested on x86_64-linux and i686-linux, ok for trunk?\n\nOK. Please extend it to all DECL_VALUE_EXPR cases for GCC 17.\n\n> 2026-04-14 Jakub Jelinek \n> \n> \tPR c++/124850\n> \t* typeck.cc (cxx_mark_addressable): For DECL_ANON_UNION_VAR_P vars\n> \talso mark their DECL_VALUE_EXPR.\n> \n> \t* g++.dg/other/anon-union8.C: New test.\n> \n> --- gcc/cp/typeck.cc.jj\t2026-04-10 08:45:20.717811786 +0200\n> +++ gcc/cp/typeck.cc\t2026-04-13 12:22:59.261032495 +0200\n> @@ -8281,6 +8281,10 @@ cxx_mark_addressable (tree exp, bool arr\n> \t\t || DECL_IN_AGGR_P (x) == 0\n> \t\t || TREE_STATIC (x)\n> \t\t || DECL_EXTERNAL (x));\n> +\tif (VAR_P (x)\n> +\t && DECL_ANON_UNION_VAR_P (x)\n> +\t && !TREE_ADDRESSABLE (x))\n> +\t cxx_mark_addressable (DECL_VALUE_EXPR (x));\n> \t/* Fall through. */\n> \n> case RESULT_DECL:\n> --- gcc/testsuite/g++.dg/other/anon-union8.C.jj\t2026-04-13 12:25:10.095803730 +0200\n> +++ gcc/testsuite/g++.dg/other/anon-union8.C\t2026-04-13 12:23:51.409144168 +0200\n> @@ -0,0 +1,11 @@\n> +// PR c++/124850\n> +// { dg-do compile }\n> +\n> +static union { int i; };\n> +int &r = i;\n> +\n> +int\n> +foo ()\n> +{\n> + return r;\n> +}\n> \n> \tJakub\n>","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=NhYi9POF;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org\n (client-ip=2620:52:6:3111::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=NhYi9POF","sourceware.org; dmarc=pass (p=quarantine dis=none)\n header.from=redhat.com","sourceware.org; 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