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GET /api/1.1/patches/2232325/?format=api
{ "id": 2232325, "url": "http://patchwork.ozlabs.org/api/1.1/patches/2232325/?format=api", "web_url": "http://patchwork.ozlabs.org/project/gcc/patch/20260504113050.155608-2-josef.melcr@suse.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": "<20260504113050.155608-2-josef.melcr@suse.com>", "date": "2026-05-04T11:30:51", "name": "[v3] Add callback_only attribute", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "a250e496811437d6bbfc40a880759593bd6c1fca", "submitter": { "id": 92126, "url": "http://patchwork.ozlabs.org/api/1.1/people/92126/?format=api", "name": "Josef Melcr", "email": "josef.melcr@suse.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/gcc/patch/20260504113050.155608-2-josef.melcr@suse.com/mbox/", "series": [ { "id": 502648, "url": "http://patchwork.ozlabs.org/api/1.1/series/502648/?format=api", "web_url": "http://patchwork.ozlabs.org/project/gcc/list/?series=502648", "date": "2026-05-04T11:30:51", "name": "[v3] Add callback_only attribute", "version": 3, "mbox": "http://patchwork.ozlabs.org/series/502648/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2232325/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2232325/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 (2048-bit key;\n unprotected) header.d=suse.com header.i=@suse.com header.a=rsa-sha256\n header.s=google header.b=MiljsYJg;\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 (2048-bit key,\n unprotected) header.d=suse.com header.i=@suse.com header.a=rsa-sha256\n header.s=google header.b=MiljsYJg", "sourceware.org; dmarc=pass (p=quarantine dis=none)\n header.from=suse.com", "sourceware.org; spf=pass smtp.mailfrom=suse.com", "server2.sourceware.org;\n arc=none smtp.remote-ip=2a00:1450:4864:20::329" ], "Received": [ "from vm01.sourceware.org (vm01.sourceware.org\n [IPv6:2620:52:6:3111::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 4g8KHj28YBz1yJ9\n\tfor <incoming@patchwork.ozlabs.org>; Mon, 04 May 2026 21:32:15 +1000 (AEST)", "from vm01.sourceware.org (localhost [127.0.0.1])\n\tby sourceware.org (Postfix) with ESMTP id DD2044BAD173\n\tfor <incoming@patchwork.ozlabs.org>; Mon, 4 May 2026 11:32:13 +0000 (GMT)", "from mail-wm1-x329.google.com (mail-wm1-x329.google.com\n [IPv6:2a00:1450:4864:20::329])\n by sourceware.org (Postfix) with ESMTPS id 813814BABF23\n for <gcc-patches@gcc.gnu.org>; Mon, 4 May 2026 11:31:42 +0000 (GMT)", "by mail-wm1-x329.google.com with SMTP id\n 5b1f17b1804b1-4896c22fcbaso28730605e9.0\n for <gcc-patches@gcc.gnu.org>; Mon, 04 May 2026 04:31:42 -0700 (PDT)", "from tumbleweed.suse.cz (nat2.prg.suse.com. 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It also fixes some missing bounds checks\nin the attribute handler. The attribute is not recognized outside of\nthe gnu namespace, I did this so that there is no accidental mixup with\nthe LLVM callback attribute, which has different syntax. I am not great\nat user-facing documentation, I hope the docs are clear about the\nattribute's usage. Suggestions are of course welcome.\n\nOK for master?\n\nBest regards,\nJosef\n\ngcc/ChangeLog:\n\n\t* attr-callback.cc (callback_edge_callee_has_attr): Specify gnu\n\tnamespace in attribute lookup.\n\t(callback_fetch_attr_by_edge): Likewise.\n\t(handle_callback_attribute): Fix bugs in bounds checks, add gnu\n\tnamespace to attribute lookup.\n\t* attr-callback.h (CALLBACK_ATTR_IDENT): Change identifier to\n\t'callback_only'.\n\t* builtin-attrs.def (ATTR_CALLBACK): Likewise.\n\t* cgraph.cc (cgraph_edge::redirect_call_stmt_to_callee): Specify\n\tgnu namespace in attribute lookup.\n\t(cgraph_node::verify_node): Likewise.\n\t* doc/extend.texi: Add gnu::callback_only attribute\n\tdocumentation.\n\t* ipa-cp.cc (purge_useless_callback_edges): Specify gnu\n\tnamespace in attribute lookup.\n\t* ipa-prop.cc (ipa_compute_jump_functions_for_edge): Likewise.\n\t* tree-core.h: Change ECF_CB_* comment from 'callback' to\n\t'callback_only'.\n\ngcc/c-family/ChangeLog:\n\n\t* c-attribs.cc: Define the 'callback_only' attribute in gnu\n\tnamespace only.\n\t* c-common.h: Add extern decl for the callback attribute table.\n\ngcc/c/ChangeLog:\n\n\t* c-objc-common.h: Add the callback attribute table to allow it\n\tto be registered.\n\ngcc/cp/ChangeLog:\n\n\t* cp-objcp-common.h: Likewise.\n\ngcc/testsuite/ChangeLog:\n\n\t* gcc.dg/attr-callback.c: New test.\n\t* gcc.dg/ipa/ipcp-cb2.c: New test.\n\nSigned-off-by: Josef Melcr <josef.melcr@suse.com>\n---\n gcc/attr-callback.cc | 20 ++---\n gcc/attr-callback.h | 2 +-\n gcc/builtin-attrs.def | 2 +-\n gcc/c-family/c-attribs.cc | 13 +++-\n gcc/c-family/c-common.h | 1 +\n gcc/c/c-objc-common.h | 3 +-\n gcc/cgraph.cc | 12 +--\n gcc/cp/cp-objcp-common.h | 1 +\n gcc/doc/extend.texi | 39 ++++++++++\n gcc/ipa-cp.cc | 2 +-\n gcc/ipa-prop.cc | 4 +-\n gcc/testsuite/gcc.dg/attr-callback.c | 107 +++++++++++++++++++++++++++\n gcc/testsuite/gcc.dg/ipa/ipcp-cb2.c | 60 +++++++++++++++\n gcc/tree-core.h | 2 +-\n 14 files changed, 245 insertions(+), 23 deletions(-)\n create mode 100755 gcc/testsuite/gcc.dg/attr-callback.c\n create mode 100644 gcc/testsuite/gcc.dg/ipa/ipcp-cb2.c", "diff": "diff --git a/gcc/attr-callback.cc b/gcc/attr-callback.cc\nindex c654d74164d..041e2463592 100644\n--- a/gcc/attr-callback.cc\n+++ b/gcc/attr-callback.cc\n@@ -87,7 +87,7 @@ callback_special_case_attr (tree decl)\n bool\n callback_edge_callee_has_attr (cgraph_edge *e)\n {\n- return lookup_attribute (CALLBACK_ATTR_IDENT,\n+ return lookup_attribute (\"gnu\", CALLBACK_ATTR_IDENT,\n \t\t\t DECL_ATTRIBUTES (e->callee->decl))\n \t || callback_is_special_cased (e->callee->decl, e->call_stmt);\n }\n@@ -113,12 +113,12 @@ callback_fetch_attr_by_edge (cgraph_edge *e, cgraph_edge *carrying)\n if (callback_is_special_cased (carrying->callee->decl, e->call_stmt))\n return callback_special_case_attr (carrying->callee->decl);\n \n- tree cb_attr = lookup_attribute (CALLBACK_ATTR_IDENT,\n+ tree cb_attr = lookup_attribute (\"gnu\", CALLBACK_ATTR_IDENT,\n \t\t\t\t DECL_ATTRIBUTES (carrying->callee->decl));\n gcc_checking_assert (cb_attr);\n tree res = NULL_TREE;\n- for (; cb_attr;\n- cb_attr = lookup_attribute (CALLBACK_ATTR_IDENT, TREE_CHAIN (cb_attr)))\n+ for (; cb_attr; cb_attr = lookup_attribute (\"gnu\", CALLBACK_ATTR_IDENT,\n+\t\t\t\t\t TREE_CHAIN (cb_attr)))\n {\n unsigned id = callback_get_fn_index (cb_attr);\n if (id == e->callback_id)\n@@ -229,10 +229,11 @@ handle_callback_attribute (tree *node, tree name, tree args,\n return NULL_TREE;\n }\n --callback_fn_idx;\n- if (callback_fn_idx >= decl_nargs)\n+ if (callback_fn_idx < 0 || callback_fn_idx >= decl_nargs)\n {\n error_at (DECL_SOURCE_LOCATION (decl),\n-\t\t\"callback function position out of range\");\n+\t\t\"callback function index %d is out of range\",\n+\t\tcallback_fn_idx + 1);\n *no_add_attrs = true;\n return NULL_TREE;\n }\n@@ -305,7 +306,7 @@ handle_callback_attribute (tree *node, tree name, tree args,\n arg_idx -= 1;\n /* Report an error if the position is out of bounds,\n \t but we can still check the rest of the arguments. */\n- if (arg_idx >= decl_nargs)\n+ if (arg_idx < 0 || arg_idx >= decl_nargs)\n \t{\n \t error_at (DECL_SOURCE_LOCATION (decl),\n \t\t \"callback argument index %d is out of range\", arg_idx + 1);\n@@ -331,8 +332,9 @@ handle_callback_attribute (tree *node, tree name, tree args,\n \n /* Check that the decl does not already have a callback attribute describing\n the same argument. */\n- it = lookup_attribute (CALLBACK_ATTR_IDENT, DECL_ATTRIBUTES (decl));\n- for (; it; it = lookup_attribute (CALLBACK_ATTR_IDENT, TREE_CHAIN (it)))\n+ it = lookup_attribute (\"gnu\", CALLBACK_ATTR_IDENT, DECL_ATTRIBUTES (decl));\n+ for (; it;\n+ it = lookup_attribute (\"gnu\", CALLBACK_ATTR_IDENT, TREE_CHAIN (it)))\n if (callback_get_fn_index (it) == callback_fn_idx)\n {\n \terror_at (DECL_SOURCE_LOCATION (decl),\ndiff --git a/gcc/attr-callback.h b/gcc/attr-callback.h\nindex b2c1c3c09c5..e51c4c6c571 100644\n--- a/gcc/attr-callback.h\n+++ b/gcc/attr-callback.h\n@@ -28,7 +28,7 @@ enum callback_position\n CB_UNKNOWN_POS = 0\n };\n \n-#define CALLBACK_ATTR_IDENT \" callback\"\n+#define CALLBACK_ATTR_IDENT \"callback_only\"\n \n /* Returns a callback attribute with callback index FN_IDX, and ARG_COUNT\n arguments specified by VA_ARGS. */\ndiff --git a/gcc/builtin-attrs.def b/gcc/builtin-attrs.def\nindex be80184b1a1..a395f454be1 100644\n--- a/gcc/builtin-attrs.def\n+++ b/gcc/builtin-attrs.def\n@@ -130,7 +130,7 @@ DEF_ATTR_IDENT (ATTR_TM_TMPURE, \"transaction_pure\")\n DEF_ATTR_IDENT (ATTR_RETURNS_TWICE, \"returns_twice\")\n DEF_ATTR_IDENT (ATTR_RETURNS_NONNULL, \"returns_nonnull\")\n DEF_ATTR_IDENT (ATTR_WARN_UNUSED_RESULT, \"warn_unused_result\")\n-DEF_ATTR_IDENT (ATTR_CALLBACK, \" callback\")\n+DEF_ATTR_IDENT (ATTR_CALLBACK, \"callback_only\")\n \n DEF_ATTR_TREE_LIST (ATTR_NOVOPS_LIST, ATTR_NOVOPS, ATTR_NULL, ATTR_NULL)\n \ndiff --git a/gcc/c-family/c-attribs.cc b/gcc/c-family/c-attribs.cc\nindex d437c55285e..598acc70d9f 100644\n--- a/gcc/c-family/c-attribs.cc\n+++ b/gcc/c-family/c-attribs.cc\n@@ -485,8 +485,6 @@ const struct attribute_spec c_common_gnu_attributes[] =\n \t\t\t handle_tm_attribute, NULL },\n { \"transaction_may_cancel_outer\", 0, 0, false, true, false, false,\n \t\t\t handle_tm_attribute, NULL },\n- { CALLBACK_ATTR_IDENT, 1, -1, true, false, false, false,\n-\t\t\t handle_callback_attribute, NULL },\n /* ??? These two attributes didn't make the transition from the\n Intel language document to the multi-vendor language document. */\n { \"transaction_pure\", 0, 0, false, true, false, false,\n@@ -707,6 +705,17 @@ const struct scoped_attribute_specs c_common_format_attribute_table =\n \"gnu\", { c_common_format_attributes }\n };\n \n+/* Attribute table for the callback attribute to be used by the C frontends.\n+ We don't want to expose the attribute outside of the GNU namespace, so it\n+ has to be separated out. */\n+const struct attribute_spec c_common_callback_attribute[] = {\n+ { CALLBACK_ATTR_IDENT, 1, -1, true, false, false, false,\n+ handle_callback_attribute, NULL },\n+};\n+\n+const struct scoped_attribute_specs c_common_callback_attribute_table\n+ = { \"gnu\", { c_common_callback_attribute } };\n+\n /* Returns TRUE iff the attribute indicated by ATTR_ID takes a plain\n identifier as an argument, so the front end shouldn't look it up. */\n \ndiff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h\nindex a4cd6786109..bcd23f098d0 100644\n--- a/gcc/c-family/c-common.h\n+++ b/gcc/c-family/c-common.h\n@@ -832,6 +832,7 @@ extern struct visibility_flags visibility_options;\n extern const struct scoped_attribute_specs c_common_gnu_attribute_table;\n extern const struct scoped_attribute_specs c_common_clang_attribute_table;\n extern const struct scoped_attribute_specs c_common_format_attribute_table;\n+extern const struct scoped_attribute_specs c_common_callback_attribute_table;\n \n /* Pointer to function to lazily generate the VAR_DECL for __FUNCTION__ etc.\n ID is the identifier to use, NAME is the string.\ndiff --git a/gcc/c/c-objc-common.h b/gcc/c/c-objc-common.h\nindex e103646b67e..11f08a2f0ca 100644\n--- a/gcc/c/c-objc-common.h\n+++ b/gcc/c/c-objc-common.h\n@@ -82,7 +82,8 @@ static const scoped_attribute_specs *const c_objc_attribute_table[] =\n &std_attribute_table,\n &c_common_gnu_attribute_table,\n &c_common_clang_attribute_table,\n- &c_common_format_attribute_table\n+ &c_common_format_attribute_table,\n+ &c_common_callback_attribute_table\n };\n \n #undef LANG_HOOKS_ATTRIBUTE_TABLE\ndiff --git a/gcc/cgraph.cc b/gcc/cgraph.cc\nindex 353e8b498aa..85a717bf865 100644\n--- a/gcc/cgraph.cc\n+++ b/gcc/cgraph.cc\n@@ -1843,7 +1843,7 @@ cgraph_edge::redirect_call_stmt_to_callee (cgraph_edge *e,\n {\n cgraph_edge *carrying = e->get_callback_carrying_edge ();\n if (!callback_is_special_cased (carrying->callee->decl, e->call_stmt)\n-\t && !lookup_attribute (CALLBACK_ATTR_IDENT,\n+\t && !lookup_attribute (\"gnu\", CALLBACK_ATTR_IDENT,\n \t\t\t\tDECL_ATTRIBUTES (carrying->callee->decl)))\n \t/* Callback attribute is removed if the dispatching function changes\n \t signature, as the indices wouldn't be correct anymore. These edges\n@@ -4419,11 +4419,13 @@ cgraph_node::verify_node (void)\n \t {\n \t int ncallbacks = 0;\n \t int nfound_edges = 0;\n-\t for (tree cb = lookup_attribute (CALLBACK_ATTR_IDENT, DECL_ATTRIBUTES (\n-\t\t\t\t\t\t\t e->callee->decl));\n-\t\t cb; cb = lookup_attribute (CALLBACK_ATTR_IDENT, TREE_CHAIN (cb)),\n-\t\t\tncallbacks++)\n+\t for (tree cb\n+\t\t = lookup_attribute (\"gnu\", CALLBACK_ATTR_IDENT,\n+\t\t\t\t DECL_ATTRIBUTES (e->callee->decl));\n+\t\t cb; cb = lookup_attribute (\"gnu\", CALLBACK_ATTR_IDENT,\n+\t\t\t\t\t TREE_CHAIN (cb)), ncallbacks++)\n \t\t;\n+\n \t for (cgraph_edge *cbe = callees; cbe; cbe = cbe->next_callee)\n \t\t{\n \t\t if (cbe->callback && cbe->call_stmt == e->call_stmt\ndiff --git a/gcc/cp/cp-objcp-common.h b/gcc/cp/cp-objcp-common.h\nindex ed29e65e4f3..4a4c6de1aea 100644\n--- a/gcc/cp/cp-objcp-common.h\n+++ b/gcc/cp/cp-objcp-common.h\n@@ -131,6 +131,7 @@ static const scoped_attribute_specs *const cp_objcp_attribute_table[] =\n &c_common_gnu_attribute_table,\n &c_common_clang_attribute_table,\n &c_common_format_attribute_table,\n+ &c_common_callback_attribute_table,\n &internal_attribute_table\n };\n \ndiff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi\nindex 8dd0b3137bc..b6505e3914a 100644\n--- a/gcc/doc/extend.texi\n+++ b/gcc/doc/extend.texi\n@@ -2357,6 +2357,45 @@ Note that the BTF format currently only has a representation for type\n tags associated with pointer types. Type tags on non-pointer types\n may be silently skipped when generating BTF.\n \n+@atindex @code{callback_only}\n+@cindex functions with callbacks\n+@item callback_only\n+The @code{callback_only} attribute specifies that the annotated function may\n+call the specified callback function. The first parameter identifies the index\n+of the callback function, the rest of the arguments specify the indices of the\n+arguments of the indirect call. All indices start from 1. If the function takes\n+the implicit @code{this} pointer, it is referred to by the index 1, with the\n+rest of the arguments starting at index 2. The index 0 marks an argument not\n+present in the arguments of the annotated function, an argument which is\n+modified before calling the callback function. The annotated function must pass\n+the specified arguments in the specified order to the callback function, which\n+must be callable with the number, order and type of the arguments. The\n+specified pointer to the callback may not escape the translation unit of the\n+annotated function and it may not be captured. The annotated function is\n+required to pass the arguments through, it may not change or dereference them.\n+The arguments also may not escape. The attribute may be used multiple times per\n+function, though only one @code{callback_only} attribute may be used per\n+function parameter.\n+\n+The attribute exposes the potentially hidden callsite in the annotated\n+function, enabling interprocedural optimizations which may not be possible\n+without the attribute. It is most useful for annotating functions from\n+dynamically linked libraries, as their bodies are not available during\n+compilation.\n+\n+This attribute is similar to the clang @code{callback} attribute but it is not\n+compatible with it. The clang implementation allows identifiers as arguments,\n+marks an unknown argument with -1 and the @code{this} pointer with the index 0.\n+\n+An example usage:\n+\n+@smallexample\n+[[gnu::callback_only(1, 3, 2)]]\n+void foo(void (*bar)(int*, double*), double* y, int* x);\n+@end smallexample\n+\n+means that there is a call @code{bar (x, y)} inside @code{foo}.\n+\n @atindex @code{cleanup}\n @cindex cleanup functions\n @item cleanup (@var{cleanup_function})\ndiff --git a/gcc/ipa-cp.cc b/gcc/ipa-cp.cc\nindex 337fca71013..763ec9db8ae 100644\n--- a/gcc/ipa-cp.cc\n+++ b/gcc/ipa-cp.cc\n@@ -6505,7 +6505,7 @@ purge_useless_callback_edges ()\n \t if (dump_file)\n \t\tfprintf (dump_file, \"\\tExamining callbacks of edge %s -> %s:\\n\",\n \t\t\t e->caller->dump_name (), e->callee->dump_name ());\n-\t if (!lookup_attribute (CALLBACK_ATTR_IDENT,\n+\t if (!lookup_attribute (\"gnu\", CALLBACK_ATTR_IDENT,\n \t\t\t\t DECL_ATTRIBUTES (e->callee->decl))\n \t\t && !callback_is_special_cased (e->callee->decl, e->call_stmt))\n \t\t{\ndiff --git a/gcc/ipa-prop.cc b/gcc/ipa-prop.cc\nindex cb89934ee38..f34ca56dd4f 100644\n--- a/gcc/ipa-prop.cc\n+++ b/gcc/ipa-prop.cc\n@@ -2608,11 +2608,11 @@ ipa_compute_jump_functions_for_edge (struct ipa_func_body_info *fbi,\n \t\t /* Argument is a pointer to a function. Look for a callback\n \t\t attribute describing this argument. */\n \t\t tree callback_attr\n-\t\t = lookup_attribute (CALLBACK_ATTR_IDENT,\n+\t\t = lookup_attribute (\"gnu\", CALLBACK_ATTR_IDENT,\n \t\t\t\t\tDECL_ATTRIBUTES (cs->callee->decl));\n \t\t for (; callback_attr;\n \t\t callback_attr\n-\t\t = lookup_attribute (CALLBACK_ATTR_IDENT,\n+\t\t = lookup_attribute (\"gnu\", CALLBACK_ATTR_IDENT,\n \t\t\t\t\t TREE_CHAIN (callback_attr)))\n \t\t if (callback_get_fn_index (callback_attr) == n)\n \t\t break;\ndiff --git a/gcc/testsuite/gcc.dg/attr-callback.c b/gcc/testsuite/gcc.dg/attr-callback.c\nnew file mode 100755\nindex 00000000000..a45ad8464cd\n--- /dev/null\n+++ b/gcc/testsuite/gcc.dg/attr-callback.c\n@@ -0,0 +1,107 @@\n+/* Test callback attribute error checking. */\n+\n+/* { dg-do compile } */\n+/* { dg-options \"-std=gnu17 -Wattributes\" } */\n+\n+[[gnu::callback_only(1, 2)]]\n+void\n+correct_1(void (*)(int*), int*);\n+\n+[[gnu::callback_only(1, 2, 3)]]\n+void\n+correct_2(void (*)(int*, double*), int*, double*);\n+\n+[[gnu::callback_only(1, 2, 3), gnu::callback_only(4, 5)]]\n+void\n+correct_3(void (*)(int*, double*), int*, double*, int (*)(void*), void*);\n+\n+[[gnu::callback_only(1, 0)]]\n+void\n+unknown_1(void (*)(int*));\n+\n+[[gnu::callback_only(1, 2, 0)]]\n+void\n+unknown_2(void (*)(int*, double*), int*, double*, char*);\n+\n+[[gnu::callback_only(1, 0, 3, 3)]]\n+void\n+too_many(void (*)(int*, double*), int*, double*); /* { dg-error \"argument number mismatch, 2 expected, got 3\" }*/\n+\n+[[gnu::callback_only(1, 2)]]\n+void\n+too_few_1(void (*)(int*, double*), int*, double*); /* { dg-error \"argument number mismatch, 2 expected, got 1\" }*/\n+\n+[[gnu::callback_only(1)]]\n+void\n+too_few_2(void (*)(int*, double*), int*, double*); /* { dg-error \"argument number mismatch, 2 expected, got 0\" }*/\n+\n+[[gnu::callback_only(3, 1)]]\n+void\n+promotion(char*, float, int (*)(int*));\n+\n+[[gnu::callback_only(2, 3)]]\n+void\n+downcast(char*, void* (*)(float*), double*);\n+\n+[[gnu::callback_only(1, 2, 5)]]\n+void\n+out_of_range_1(char (*)(float*, double*), float*, double*, int*); /* { dg-error \"callback argument index 5 is out of range\" } */\n+\n+[[gnu::callback_only(1, -2, 3)]]\n+void\n+out_of_range_2(char (*)(float*, double*), float*, double*, int*); /* { dg-error \"callback argument index -2 is out of range\" } */\n+\n+[[gnu::callback_only(-1, 2, 3)]]\n+void\n+out_of_range_3(char (*)(float*, double*), float*, double*, int*); /* { dg-error \"callback function index -1 is out of range\" } */\n+\n+[[gnu::callback_only(67, 2, 3)]]\n+void\n+out_of_range_4(char (*)(float*, double*), float*, double*, int*); /* { dg-error \"callback function index 67 is out of range\" } */\n+\n+[[gnu::callback_only(0, 2, 3)]]\n+void\n+unknown_fn(char (*)(float*, double*), float*, double*, int*); /* { dg-error \"callback function position cannot be marked as unknown\" } */\n+\n+[[gnu::callback_only(1, 2)]]\n+void\n+not_a_fn(int, int); /* { dg-error \"argument no. 1 is not an address of a function\" } */\n+\n+struct S\n+{\n+ int x;\n+};\n+\n+[[gnu::callback_only(1, 2)]]\n+void\n+incompatible_types_1(void (*)(struct S*), struct S); /* { dg-error \"argument type at index 2 is not compatible with callback argument type at index 1\" } */\n+\n+[[gnu::callback_only(1, 3, 2)]]\n+void\n+incompatible_types_2(void (*)(struct S*, int*), int*, double); /* { dg-error \"argument type at index 3 is not compatible with callback argument type at index 1\" } */\n+\n+[[gnu::callback_only(1, \"2\")]]\n+void\n+wrong_arg_type_1(void (*)(void*), void*); /* { dg-error \"argument no. 1 is not an integer constant\" } */\n+\n+[[gnu::callback_only(\"not a number\", 2, 2)]]\n+void\n+wrong_arg_type_2(void (*)(void*, void*), void*); /* { dg-error \"argument specifying callback function position is not an integer constant\" } */\n+\n+[[gnu::callback_only(1, 2), gnu::callback_only(1, 3)]]\n+void\n+multiple_single_fn(void (*)(int*), int*, int*); /* { dg-error \"function declaration has multiple callback attributes describing argument no. 1\" } */\n+\n+/* Check that the attribute won't resolve outside of our namespace. */\n+\n+[[callback_only(1, 2)]] /* { dg-warning \"ignored\" } */\n+void\n+ignore_1(void (*)(int*), int*);\n+\n+[[callback(1, 2)]] /* { dg-warning \"ignored\" } */\n+void\n+ignore_2(void (*)(int*), int*);\n+\n+[[gnu::callback(1, 2)]]\n+void\n+ignore_3(void (*)(int*), int*); /* { dg-warning \"ignored\" } */\ndiff --git a/gcc/testsuite/gcc.dg/ipa/ipcp-cb2.c b/gcc/testsuite/gcc.dg/ipa/ipcp-cb2.c\nnew file mode 100644\nindex 00000000000..201d41d48f3\n--- /dev/null\n+++ b/gcc/testsuite/gcc.dg/ipa/ipcp-cb2.c\n@@ -0,0 +1,60 @@\n+/* Test that we can handle multiple callback attributes and use them to\n+ propagate into callbacks. 'cb1' body borrowed from a ipa-cp test to get the\n+ pass to work. */\n+\n+/* { dg-do compile } */\n+/* { dg-options \"-O3 -fdump-ipa-cp\" } */\n+\n+struct S\n+{\n+ int a, b, c;\n+};\n+\n+extern void *blah (int, void *);\n+\n+[[gnu::callback_only (1, 2), gnu::callback_only (3, 4, 5)]] extern void\n+call (void (*fn1) (struct S *), struct S *a,\n+ void (*fn2) (struct S *, struct S *), struct S *b, struct S *c);\n+\n+void\n+cb1 (struct S *p)\n+{\n+ int i, c = p->c;\n+ int b = p->b;\n+ void *v = (void *) p;\n+\n+ for (i = 0; i < c; i++)\n+ v = blah (b + i, v);\n+}\n+\n+void\n+cb2 (struct S *a, struct S *b)\n+{\n+ cb1 (a);\n+ cb1 (b);\n+}\n+\n+void\n+test (int a, int b, int c)\n+{\n+ struct S s;\n+ s.a = a;\n+ s.b = b;\n+ s.c = c;\n+ struct S ss;\n+ ss.a = s.c;\n+ ss.b = s.b;\n+ ss.c = s.a;\n+ call (cb1, &s, cb2, &s, &ss);\n+}\n+\n+int\n+main ()\n+{\n+ test (1, 64, 32);\n+ return 0;\n+}\n+\n+/* { dg-final { scan-ipa-dump \"Creating a specialized node of cb1\" \"cp\" } } */\n+/* { dg-final { scan-ipa-dump \"Creating a specialized node of cb2\" \"cp\" } } */\n+/* { dg-final { scan-ipa-dump-times \"Aggregate replacements: \" 2 \"cp\" } } */\ndiff --git a/gcc/tree-core.h b/gcc/tree-core.h\nindex 07e9318f5e8..0169c0d4c67 100644\n--- a/gcc/tree-core.h\n+++ b/gcc/tree-core.h\n@@ -102,7 +102,7 @@ struct die_struct;\n meant to be used for the construction of builtin functions. They were only\n added because Fortran uses them for attributes of builtins. */\n \n-/* callback(1, 2) */\n+/* callback_only(1, 2) */\n #define ECF_CB_1_2\t\t (1 << 17)\n \n /* Call argument flags. */\n", "prefixes": [ "v3" ] }