[{"id":3673802,"web_url":"http://patchwork.ozlabs.org/comment/3673802/","msgid":"","list_archive_url":null,"date":"2026-04-06T16:43:27","subject":"Re: [PATCH] c++/modules: Only mark namespace-scope entities as\n exported [PR124781]","submitter":{"id":4337,"url":"http://patchwork.ozlabs.org/api/people/4337/","name":"Jason Merrill","email":"jason@redhat.com"},"content":"On 4/5/26 9:34 AM, Nathaniel Shead wrote:\n> Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk/15?\n\nOK.\n\n> -- >8 --\n> \n> We call 'set_originating_module' before we call pushdecl, which means\n> that for function-scope entities we might not have set DECL_CONTEXT yet.\n> Usually this doesn't matter, we only look at DECL_MODULE_EXPORT/ATTACH_P\n> on namespace-scope entities to begin with, but in the case in the linked\n> PR it causes issues because declarations in an unevaluated lambda appear\n> to be in an internal context.\n> \n> Fixed by only considering non-null DECL_CONTEXT as being namespace scope\n> within set_originating_module.\n> \n> As a drive-by improvement, ensured that we only talk about unnamed\n> namespaces in the diagnostic within check_module_decl_linkage if we're\n> actually within an anonymous namespace; this should be equivalent but\n> will lead to a slightly clearer diagnostic if a similar bug crops up\n> again later.\n> \n> \tPR c++/124781\n> \n> gcc/cp/ChangeLog:\n> \n> \t* module.cc (set_originating_module): Add a function comment,\n> \tonly set attachment/exporting for entities with non-NULL\n> \tDECL_CONTEXT.\n> \t(check_module_decl_linkage): Use decl_anon_ns_mem_p instead of\n> \tdecl_internal_context_p.\n> \n> gcc/testsuite/ChangeLog:\n> \n> \t* g++.dg/modules/export-7.C: New test.\n> \n> Signed-off-by: Nathaniel Shead \n> ---\n> gcc/cp/module.cc | 10 ++++++++--\n> gcc/testsuite/g++.dg/modules/export-7.C | 10 ++++++++++\n> 2 files changed, 18 insertions(+), 2 deletions(-)\n> create mode 100644 gcc/testsuite/g++.dg/modules/export-7.C\n> \n> diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc\n> index 6958388e454..a8517569a1b 100644\n> --- a/gcc/cp/module.cc\n> +++ b/gcc/cp/module.cc\n> @@ -22076,12 +22076,18 @@ set_defining_module_for_partial_spec (tree decl)\n> vec_safe_push (partial_specializations, decl);\n> }\n> \n> +/* Record that DECL is declared in this TU, and note attachment and\n> + exporting for namespace-scope entities. FRIEND_P is true if\n> + this is a friend declaration. */\n> +\n> void\n> set_originating_module (tree decl, bool friend_p ATTRIBUTE_UNUSED)\n> {\n> set_instantiating_module (decl);\n> \n> - if (!DECL_NAMESPACE_SCOPE_P (decl))\n> + /* DECL_CONTEXT may not be set yet when we're called for\n> + non-namespace-scope entities. */\n> + if (!DECL_CONTEXT (decl) || !DECL_NAMESPACE_SCOPE_P (decl))\n> return;\n> \n> gcc_checking_assert (friend_p || decl == get_originating_module_decl (decl));\n> @@ -22134,7 +22140,7 @@ check_module_decl_linkage (tree decl)\n> \t internal namespace as exporting a declaration with internal\n> \t linkage, as this would also implicitly export the internal\n> \t linkage namespace. */\n> - if (decl_internal_context_p (decl))\n> + if (decl_anon_ns_mem_p (decl))\n> \t{\n> \t error_at (DECL_SOURCE_LOCATION (decl),\n> \t\t \"exporting declaration %qD declared in unnamed namespace\",\n> diff --git a/gcc/testsuite/g++.dg/modules/export-7.C b/gcc/testsuite/g++.dg/modules/export-7.C\n> new file mode 100644\n> index 00000000000..11001390d17\n> --- /dev/null\n> +++ b/gcc/testsuite/g++.dg/modules/export-7.C\n> @@ -0,0 +1,10 @@\n> +// PR c++/124781\n> +// { dg-do compile { target c++20 } }\n> +// { dg-additional-options \"-fmodules\" }\n> +// { dg-module-cmi foo }\n> +\n> +export module foo;\n> +export using xx = decltype([] {\n> + using yy = int;\n> + int abc = 123;\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=FlTTG3jO;\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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