[{"id":3673796,"web_url":"http://patchwork.ozlabs.org/comment/3673796/","msgid":"<565a3f92-cb8a-4b88-b689-8bfe4233f2bd@redhat.com>","list_archive_url":null,"date":"2026-04-06T16:36:16","subject":"Re: [PATCH] c++, v3: Implement the annotations_of on parms part of\n P3795R1","submitter":{"id":4337,"url":"http://patchwork.ozlabs.org/api/people/4337/","name":"Jason Merrill","email":"jason@redhat.com"},"content":"On 4/6/26 2:18 AM, Jakub Jelinek wrote:\n> On Fri, Apr 03, 2026 at 04:37:20PM -0400, Jason Merrill wrote:\n>> \"void_node\"\n> \n> Changed.\n> \n>>> +\t tree val = TREE_VALUE (a);\n>>> +\t if (TREE_PURPOSE (val) == NULL_TREE)\n>>> +\t TREE_PURPOSE (val) = void_node;\n>>> +\t else if (TREE_CODE (TREE_PURPOSE (val)) == INTEGER_CST)\n>>\n>> It seems impossible to have INTEGER_CST this early, we can't have tried to\n>> mangle a function we haven't even built yet. And indeed the testcase\n>> doesn't exercise this case. Maybe assert NULL_TREE instead?\n> \n> Assert added instead.\n> \n>>> +\t/* For ^^fnparm or variable_of (parameters_of (^^fn)[N])\n>>> +\t filter out annotations not specified on the function\n>>> +\t definition. */\n>>\n>> Let's also mention that purpose is set in grokfndecl or\n>> reflection_mangle_prefix.\n> \n> Done.\n> \n>> Also \"void_node\".\n> \n> Changed.\n> \n> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?\n\nOK.\n\n> 2026-04-06 Jakub Jelinek \n> \n> \t* decl.cc (grokfndecl): For -freflection mark annotations of\n> \tPARM_DECLs in a function definition.\n> \t* reflect.cc (eval_annotations_of): Allow annotations_of on\n> \tfunction parameters. For r which is a PARM_DECL without REFLECT_PARM,\n> \tfilter out annotations not marked by grokfndecl.\n> \t(reflection_mangle_prefix): Preserve the grokfndecl marking of\n> \tannotations during mangling.\n> \n> \t* g++.dg/reflect/annotations15.C: New test.\n> \n> --- gcc/cp/decl.cc.jj\t2026-03-26 07:59:59.527656320 +0100\n> +++ gcc/cp/decl.cc\t2026-03-26 12:31:36.887319793 +0100\n> @@ -12218,7 +12218,28 @@ grokfndecl (tree ctype,\n> \n> DECL_ARGUMENTS (decl) = parms;\n> for (t = parms; t; t = DECL_CHAIN (t))\n> - DECL_CONTEXT (t) = decl;\n> + {\n> + DECL_CONTEXT (t) = decl;\n> + if (flag_reflection\n> +\t && initialized == SD_INITIALIZED\n> +\t && DECL_ATTRIBUTES (t))\n> +\tfor (tree a = DECL_ATTRIBUTES (t);\n> +\t (a = lookup_attribute (\"internal \", \"annotation \", a));\n> +\t a = TREE_CHAIN (a))\n> +\t {\n> +\t gcc_checking_assert (TREE_CODE (TREE_VALUE (a)) == TREE_LIST);\n> +\t /* Mark TREE_PURPOSE of the value that it is an annotation\n> +\t on an argument of a function definition (rather than\n> +\t annotation from function declaration). For function parameter\n> +\t reflection all annotations are listed, while for variable_of\n> +\t only those marked here. Annotation is marked as coming from\n> +\t function definition's argument if it has TREE_PURPOSE\n> +\t void_node or INTEGER_CST with signed type. */\n> +\t tree val = TREE_VALUE (a);\n> +\t gcc_assert (TREE_PURPOSE (val) == NULL_TREE);\n> +\t TREE_PURPOSE (val) = void_node;\n> +\t }\n> + }\n> \n> /* Propagate volatile out from type to decl. */\n> if (TYPE_VOLATILE (type))\n> --- gcc/cp/reflect.cc.jj\t2026-03-25 20:32:38.262640083 +0100\n> +++ gcc/cp/reflect.cc\t2026-03-26 12:30:48.440143055 +0100\n> @@ -3812,14 +3812,16 @@ eval_annotations_of (location_t loc, con\n> \t|| eval_is_type_alias (r) == boolean_true_node\n> \t|| eval_is_variable (r, kind) == boolean_true_node\n> \t|| eval_is_function (r) == boolean_true_node\n> +\t|| eval_is_function_parameter (r, kind) == boolean_true_node\n> \t|| eval_is_namespace (r) == boolean_true_node\n> \t|| eval_is_enumerator (r) == boolean_true_node\n> \t|| eval_is_base (r, kind) == boolean_true_node\n> \t|| eval_is_nonstatic_data_member (r) == boolean_true_node))\n> return throw_exception (loc, ctx,\n> \t\t\t \"reflection does not represent a type,\"\n> -\t\t\t \" type alias, variable, function, namespace,\"\n> -\t\t\t \" enumerator, direct base class relationship,\"\n> +\t\t\t \" type alias, variable, function, function\"\n> +\t\t\t \" parameter, namespace, enumerator,\"\n> +\t\t\t \" direct base class relationship,\"\n> \t\t\t \" or non-static data member\",\n> \t\t\t fun, non_constant_p, jump_target);\n> \n> @@ -3836,6 +3838,7 @@ eval_annotations_of (location_t loc, con\n> }\n> \n> r = maybe_get_first_fn (r);\n> + bool var_of = false;\n> if (kind == REFLECT_BASE)\n> {\n> gcc_assert (TREE_CODE (r) == TREE_BINFO);\n> @@ -3860,7 +3863,11 @@ eval_annotations_of (location_t loc, con\n> \tr = TYPE_ATTRIBUTES (r);\n> }\n> else if (DECL_P (r))\n> - r = DECL_ATTRIBUTES (r);\n> + {\n> + if (TREE_CODE (r) == PARM_DECL && kind != REFLECT_PARM)\n> +\tvar_of = true;\n> + r = DECL_ATTRIBUTES (r);\n> + }\n> else\n> gcc_unreachable ();\n> vec *elts = nullptr;\n> @@ -3869,6 +3876,16 @@ eval_annotations_of (location_t loc, con\n> {\n> gcc_checking_assert (TREE_CODE (TREE_VALUE (a)) == TREE_LIST);\n> tree val = TREE_VALUE (TREE_VALUE (a));\n> + tree purpose = TREE_PURPOSE (TREE_VALUE (a));\n> + if (var_of\n> +\t && (purpose == NULL_TREE\n> +\t || (TREE_CODE (purpose) == INTEGER_CST\n> +\t\t && !TYPE_UNSIGNED (TREE_TYPE (purpose)))))\n> +\t/* For ^^fnparm or variable_of (parameters_of (^^fn)[N])\n> +\t filter out annotations not specified on the function\n> +\t definition. TREE_PURPOSE is set in grokfndecl and/or in\n> +\t reflection_mangle_prefix. */\n> +\tcontinue;\n> if (type)\n> \t{\n> \t tree at = TREE_TYPE (val);\n> @@ -8749,7 +8765,13 @@ reflection_mangle_prefix (tree refl, cha\n> strcpy (prefix, \"an\");\n> if (TREE_PURPOSE (TREE_VALUE (h)) == NULL_TREE)\n> \tTREE_PURPOSE (TREE_VALUE (h))\n> -\t = build_int_cst (integer_type_node, annotation_idx++);\n> +\t = bitsize_int (annotation_idx++);\n> + /* TREE_PURPOSE void_node or INTEGER_CST with signed type\n> +\t means it is annotation which should appear in\n> +\t variable_of list. */\n> + else if (TREE_PURPOSE (TREE_VALUE (h)) == void_node)\n> +\tTREE_PURPOSE (TREE_VALUE (h))\n> +\t = sbitsize_int (annotation_idx++);\n> return TREE_PURPOSE (TREE_VALUE (h));\n> }\n> if (eval_is_type_alias (h) == boolean_true_node)\n> --- gcc/testsuite/g++.dg/reflect/annotations15.C.jj\t2026-03-26 12:40:48.910963751 +0100\n> +++ gcc/testsuite/g++.dg/reflect/annotations15.C\t2026-03-26 12:40:37.661154305 +0100\n> @@ -0,0 +1,44 @@\n> +// P3795R2 - Miscellaneous Reflection Cleanup\n> +// { dg-do compile { target c++26 } }\n> +// { dg-additional-options \"-freflection\" }\n> +\n> +#include \n> +\n> +void foo ([[=1]] int x);\n> +constexpr auto rf = parameters_of (^^foo)[0];\n> +void foo ([[=2, =3]] int x);\n> +\n> +void\n> +foo ([[=4, =5]] int x)\n> +{\n> + static_assert (annotations_of (^^x).size () == 2);\n> + static_assert ([: constant_of (annotations_of (^^x)[0]) :] == 4);\n> + static_assert ([: constant_of (annotations_of (^^x)[1]) :] == 5);\n> + static_assert (annotations_of (rf).size () == 5);\n> + static_assert ([: constant_of (annotations_of (rf)[0]) :] == 1);\n> + static_assert ([: constant_of (annotations_of (rf)[1]) :] == 2);\n> + static_assert ([: constant_of (annotations_of (rf)[2]) :] == 3);\n> + static_assert ([: constant_of (annotations_of (rf)[3]) :] == 4);\n> + static_assert ([: constant_of (annotations_of (rf)[4]) :] == 5);\n> + static_assert (annotations_of (variable_of (rf)).size () == 2);\n> + static_assert ([: constant_of (annotations_of (variable_of (rf))[0]) :] == 4);\n> + static_assert ([: constant_of (annotations_of (variable_of (rf))[1]) :] == 5);\n> + static_assert (annotations_of (parameters_of (^^foo)[0]).size () == 5);\n> + static_assert ([: constant_of (annotations_of (parameters_of (^^foo)[0])[0]) :] == 1);\n> + static_assert ([: constant_of (annotations_of (parameters_of (^^foo)[0])[1]) :] == 2);\n> + static_assert ([: constant_of (annotations_of (parameters_of (^^foo)[0])[2]) :] == 3);\n> + static_assert ([: constant_of (annotations_of (parameters_of (^^foo)[0])[3]) :] == 4);\n> + static_assert ([: constant_of (annotations_of (parameters_of (^^foo)[0])[4]) :] == 5);\n> + static_assert (annotations_of (^^x)[0] == annotations_of (rf)[3]);\n> + static_assert (annotations_of (^^x)[0] == annotations_of (variable_of (rf))[0]);\n> + static_assert (annotations_of (^^x)[0] == annotations_of (parameters_of (^^foo)[0])[3]);\n> +}\n> +\n> +void foo ([[=6]] int x);\n> +static_assert (annotations_of (parameters_of (^^foo)[0]).size () == 6);\n> +static_assert ([: constant_of (annotations_of (parameters_of (^^foo)[0])[0]) :] == 1);\n> +static_assert ([: constant_of (annotations_of (parameters_of (^^foo)[0])[1]) :] == 2);\n> +static_assert ([: constant_of (annotations_of (parameters_of (^^foo)[0])[2]) :] == 3);\n> +static_assert ([: constant_of (annotations_of (parameters_of (^^foo)[0])[3]) :] == 4);\n> +static_assert ([: constant_of (annotations_of (parameters_of (^^foo)[0])[4]) :] == 5);\n> +static_assert ([: constant_of (annotations_of (parameters_of (^^foo)[0])[5]) :] == 6);\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=FXPUcGho;\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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