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GET /api/1.1/patches/2223580/?format=api
{ "id": 2223580, "url": "http://patchwork.ozlabs.org/api/1.1/patches/2223580/?format=api", "web_url": "http://patchwork.ozlabs.org/project/gcc/patch/20260415161149.691849-1-polacek@redhat.com/", "project": { "id": 17, "url": "http://patchwork.ozlabs.org/api/1.1/projects/17/?format=api", "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": "<20260415161149.691849-1-polacek@redhat.com>", "date": "2026-04-15T16:11:49", "name": "c++/reflection: generic lambda with dependent splice [PR123783]", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "dee8db103cd0bcc9c0da555e9497cb8468fb56f6", "submitter": { "id": 14370, "url": "http://patchwork.ozlabs.org/api/1.1/people/14370/?format=api", "name": "Marek Polacek", "email": "polacek@redhat.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/gcc/patch/20260415161149.691849-1-polacek@redhat.com/mbox/", "series": [ { "id": 500013, "url": "http://patchwork.ozlabs.org/api/1.1/series/500013/?format=api", "web_url": "http://patchwork.ozlabs.org/project/gcc/list/?series=500013", "date": "2026-04-15T16:11:49", "name": "c++/reflection: generic lambda with dependent splice [PR123783]", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/500013/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2223580/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2223580/checks/", "tags": {}, "headers": { "Return-Path": "<gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org>", "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=cVB60pxF;\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; 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server2.sourceware.org", "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com;\n s=mimecast20190719; t=1776269516;\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 bh=2JTE3lz+BcNlkE3dQSFOtVtFkFBq/P5OfY6jUz/eQds=;\n b=cVB60pxFIeiueWAuL4zFc8kj9APP4YAR9k+nwHOGBicKtJFeubn7smwqcdlnD5n9oD9eHG\n zyaHIOB8UIAuag4E0FxaHKYJTN4pkAXo6wX9mWXvjsn/5mvEEkv6LvVaavsa4jIZ2KO81h\n 17BYUVzoO0NMIl8dAbzR+Ap6XIv/6Qg=", "X-MC-Unique": "QDzy_mvuMRy_aF6clEa3Lg-1", "X-Mimecast-MFC-AGG-ID": "QDzy_mvuMRy_aF6clEa3Lg_1776269514", "From": "Marek Polacek <polacek@redhat.com>", "To": "GCC Patches <gcc-patches@gcc.gnu.org>,\n\tJason Merrill <jason@redhat.com>", "Subject": "[PATCH] c++/reflection: generic lambda with dependent splice\n [PR123783]", "Date": "Wed, 15 Apr 2026 12:11:49 -0400", "Message-ID": "<20260415161149.691849-1-polacek@redhat.com>", "MIME-Version": "1.0", "X-Scanned-By": "MIMEDefang 3.0 on 10.30.177.12", "X-Mimecast-Spam-Score": "0", "X-Mimecast-MFC-PROC-ID": "mqO30_APRH7t2ONDnQKtFy9Azv-JplA_asbxcYbpEko_1776269514", "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 <gcc-patches.gcc.gnu.org>", "List-Unsubscribe": "<https://gcc.gnu.org/mailman/options/gcc-patches>,\n <mailto:gcc-patches-request@gcc.gnu.org?subject=unsubscribe>", "List-Archive": "<https://gcc.gnu.org/pipermail/gcc-patches/>", "List-Post": "<mailto:gcc-patches@gcc.gnu.org>", "List-Help": "<mailto:gcc-patches-request@gcc.gnu.org?subject=help>", "List-Subscribe": "<https://gcc.gnu.org/mailman/listinfo/gcc-patches>,\n <mailto:gcc-patches-request@gcc.gnu.org?subject=subscribe>", "Errors-To": "gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org" }, "content": "Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?\n\n-- >8 --\nFor a generic lambda, we normally collect the captures while parsing\nthe lambda: finish_id_expression calls process_outer_var_ref which does\nadd_capture. Then when instantiating, we'll find the capture via\nretrieve_local_specialization. Once the closure type has been\nfinalized, it's frozen and we can't add new fields. This is what\nhappens in the following test though, which is the reason we crash:\n\n [&]<auto> {\n [:e:];\n }\n\nwhere while parsing we can't know what the splice will designate.\nWe'll only find out after we've substituted the splice but then it's\ntoo late to capture anything.\n\nA possible solution would be to speculatively capture all locals when\nwe see a dependent splice in a generic lambda. But since this test is\ninvalid anyway, that would be a lot of work for no good reason. So this\npatch changes the internal_error to an ordinary error.\n\n\tPR c++/123783\n\ngcc/cp/ChangeLog:\n\n\t* lambda.cc (add_capture): When trying to capture something in\n\tan instantiation of generic lambda, give an error instead of an ICE.\n\ngcc/testsuite/ChangeLog:\n\n\t* g++.dg/reflect/dep14.C: New test.\n\t* g++.dg/reflect/dep15.C: New test.\n---\n gcc/cp/lambda.cc | 7 +++--\n gcc/testsuite/g++.dg/reflect/dep14.C | 44 ++++++++++++++++++++++++++++\n gcc/testsuite/g++.dg/reflect/dep15.C | 44 ++++++++++++++++++++++++++++\n 3 files changed, 93 insertions(+), 2 deletions(-)\n create mode 100644 gcc/testsuite/g++.dg/reflect/dep14.C\n create mode 100644 gcc/testsuite/g++.dg/reflect/dep15.C\n\n\nbase-commit: 662a21e48e7820c9f8614b4eb4249cc8d1dc443d", "diff": "diff --git a/gcc/cp/lambda.cc b/gcc/cp/lambda.cc\nindex e1ff304ffe8..bf9eda573e1 100644\n--- a/gcc/cp/lambda.cc\n+++ b/gcc/cp/lambda.cc\n@@ -729,8 +729,11 @@ add_capture (tree lambda, tree id, tree orig_init, bool by_reference_p,\n && current_class_type == LAMBDA_EXPR_CLOSURE (lambda))\n {\n if (COMPLETE_TYPE_P (current_class_type))\n-\tinternal_error (\"trying to capture %qD in instantiation of \"\n-\t\t\t\"generic lambda\", id);\n+\t{\n+\t error (\"trying to capture %qD in instantiation of generic lambda\",\n+\t\t id);\n+\t return error_mark_node;\n+\t}\n finish_member_declaration (member);\n }\n \ndiff --git a/gcc/testsuite/g++.dg/reflect/dep14.C b/gcc/testsuite/g++.dg/reflect/dep14.C\nnew file mode 100644\nindex 00000000000..e9464e529b2\n--- /dev/null\n+++ b/gcc/testsuite/g++.dg/reflect/dep14.C\n@@ -0,0 +1,44 @@\n+// PR c++/123783\n+// { dg-do compile { target c++26 } }\n+// { dg-additional-options \"-freflection\" }\n+\n+#include <meta>\n+\n+namespace __impl {\n+ template<auto... vals>\n+ struct replicator_type {\n+ template<typename F>\n+ constexpr void operator>>(F body) const {\n+ (body.template operator()<vals>(), ...);\n+ }\n+ };\n+\n+ template<auto... vals>\n+ replicator_type<vals...> replicator = {};\n+}\n+\n+template<typename R>\n+consteval auto expand(R range) {\n+ std::vector<std::meta::info> args;\n+ for (auto r : range) {\n+ args.push_back(reflect_constant(r));\n+ }\n+ return substitute(^^__impl::replicator, args);\n+}\n+\n+int func(int counter, float factor) {\n+ std::array<void *, parameters_of(^^func).size()> args;\n+\n+ std::size_t i = 0;\n+ [:expand(parameters_of(^^func)):] >> [&]<auto e>\n+ {\n+ args[i++] = &[:e:]; // { dg-error \"use of local variable|trying to capture \\[^\\n\\r]* in instantiation of generic lambda\" }\n+ };\n+ return 0;\n+}\n+\n+int main()\n+{\n+ func(11, 22);\n+ func(33, 44);\n+}\ndiff --git a/gcc/testsuite/g++.dg/reflect/dep15.C b/gcc/testsuite/g++.dg/reflect/dep15.C\nnew file mode 100644\nindex 00000000000..060c9f680ab\n--- /dev/null\n+++ b/gcc/testsuite/g++.dg/reflect/dep15.C\n@@ -0,0 +1,44 @@\n+// PR c++/123783\n+// { dg-do compile { target c++26 } }\n+// { dg-additional-options \"-freflection\" }\n+\n+#include <meta>\n+\n+namespace __impl {\n+ template<auto... vals>\n+ struct replicator_type {\n+ template<typename F>\n+ constexpr void operator>>(F body) const {\n+ (body.template operator()<vals>(), ...);\n+ }\n+ };\n+\n+ template<auto... vals>\n+ replicator_type<vals...> replicator = {};\n+}\n+\n+template<typename R>\n+consteval auto expand(R range) {\n+ std::vector<std::meta::info> args;\n+ for (auto r : range) {\n+ args.push_back(reflect_constant(r));\n+ }\n+ return substitute(^^__impl::replicator, args);\n+}\n+\n+int func(int counter, float factor) {\n+ std::array<void *, parameters_of(^^func).size()> args;\n+\n+ std::size_t i = 0;\n+ [:expand(parameters_of(^^func)):] >> [&i, &counter, &factor, &args]<auto e>\n+ {\n+ args[i++] = &[:e:]; // { dg-error \"use of local variable\" }\n+ };\n+ return 0;\n+}\n+\n+int main()\n+{\n+ func(11, 22);\n+ func(33, 44);\n+}\n", "prefixes": [] }