{"id":2231545,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2231545/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/patch/afO3cl6JJrYYVMVu@tucnak/","project":{"id":17,"url":"http://patchwork.ozlabs.org/api/1.1/projects/17/?format=json","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":"","date":"2026-04-30T20:11:30","name":"c, c++, v2: Introduce -Wconstant-logical-operand warning [PR125081]","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"4f0e76f7491209741270a2efebc9c978f564b836","submitter":{"id":671,"url":"http://patchwork.ozlabs.org/api/1.1/people/671/?format=json","name":"Jakub Jelinek","email":"jakub@redhat.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/gcc/patch/afO3cl6JJrYYVMVu@tucnak/mbox/","series":[{"id":502375,"url":"http://patchwork.ozlabs.org/api/1.1/series/502375/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/list/?series=502375","date":"2026-04-30T20:11:30","name":"c, c++, v2: Introduce -Wconstant-logical-operand warning [PR125081]","version":1,"mbox":"http://patchwork.ozlabs.org/series/502375/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2231545/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2231545/checks/","tags":{},"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=WDCe48Ic;\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=1777579957;\n h=from:from:reply-to:reply-to:subject:subject:date:date:\n message-id:message-id:to:to:cc:cc:mime-version:mime-version:\n content-type:content-type:in-reply-to:in-reply-to: references:references;\n bh=PNn2SUaM1Q7R7zoq4dxjDFQsWMH8K+Ub8rbuTMLv1xQ=;\n b=WDCe48IczP/zuL1r+Sft3/P69vVlIlhoktsuXE0b9wRn2cOz2FUfBer8qq51p1Kqli0TKZ\n 5UV5Nsc+k1I8JvvDBamya6m8u+68abP3G1EsxDDzLXoeEWdB6r+exKAkvan6mXh2AFdzBm\n yMuHBoFrIst+Koh0P9+EQ7u/WEGClWM=","X-MC-Unique":"ZHuCUOCvNi24OSXjHO_bTw-1","X-Mimecast-MFC-AGG-ID":"ZHuCUOCvNi24OSXjHO_bTw_1777579954","Date":"Thu, 30 Apr 2026 22:11:30 +0200","From":"Jakub Jelinek ","To":"\"Joseph S. Myers\" ,\n Marek Polacek , Jason Merrill ","Cc":"gcc-patches@gcc.gnu.org","Subject":"[PATCH] c, c++, v2: Introduce -Wconstant-logical-operand warning\n [PR125081]","Message-ID":"","References":"\n <8d188ded-0e3a-426d-b3ef-6357cc98440f@redhat.com>\n \n <9acfb25a-8cb0-45f1-8059-d959d8e88b2a@redhat.com>","MIME-Version":"1.0","In-Reply-To":"<9acfb25a-8cb0-45f1-8059-d959d8e88b2a@redhat.com>","X-Scanned-By":"MIMEDefang 3.0 on 10.30.177.12","X-Mimecast-Spam-Score":"0","X-Mimecast-MFC-PROC-ID":"z_Yr1S6FfvdyeFATc7JT33dO093oPq79vFe2lB7AiAo_1777579954","X-Mimecast-Originator":"redhat.com","Content-Type":"text/plain; charset=us-ascii","Content-Disposition":"inline","X-BeenThere":"gcc-patches@gcc.gnu.org","X-Mailman-Version":"2.1.30","Precedence":"list","List-Id":"Gcc-patches mailing list ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Reply-To":"Jakub Jelinek ","Errors-To":"gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org"},"content":"On Thu, Apr 30, 2026 at 02:08:46PM -0400, Jason Merrill wrote:\n> > I can certainly implement that. Or just warn also whenever the constant is\n> > 1 with some enum type originally, I don't see why people actually would write\n> > enum { A, B }; if (x && B) unless it is a poor man's pre-C11 replacement of bool (so\n> > say typedef enum BOOL { FALSE, TRUE } BOOL;\n> > and using if (x && TRUE)). Or warn for constant 1 if it has enum type and\n> > the enum type contains more enumerators than just 0/1. One can always get\n> > rid of the warning by using && ENUM != 0 instead of just && ENUM and make\n> > the code even more readable that way.\n> \n> Sounds good.\n\nHere is another version of the patch which implements that.\nThis version would have caught the && ff_genericize case.\n\n2026-04-30 Jakub Jelinek \n\n\tPR c++/125081\ngcc/doc/\n\t* invoke.texi (Wconstant-logical-operand): Document.\ngcc/c-family/\n\t* c.opt (Wconstant-logical-operand): New option.\n\t* c.opt.urls: Regenerate.\ngcc/c/\n\t* c-tree.h (parser_build_binary_op): Add ORIG_ARG1 argument.\n\t* c-typeck.cc (parser_build_binary_op): Likewise. Emit\n\t-Wconstant-logical-operand warnings.\n\t* c-parser.cc (c_parser_binary_expression): Adjust\n\tparser_build_binary_op caller, pass to it the original\n\tstack[sp - 1].expr.value before c_objc_common_truthvalue_conversion.\ngcc/cp/\n\t* typeck.cc (cp_build_binary_op): Emit -Wconstant-logical-operand\n\twarnings.\n\t* c-c++-common/Wconstant-logical-operand-1.c: New test.\n\t* c-c++-common/Wconstant-logical-operand-2.c: New test.\n\n\n\n\tJakub","diff":"--- gcc/doc/invoke.texi.jj\t2026-04-30 10:18:13.834688557 +0200\n+++ gcc/doc/invoke.texi\t2026-04-30 22:07:50.717947812 +0200\n@@ -385,7 +385,7 @@ Objective-C and Objective-C++ Dialects}.\n -Wchar-subscripts\n -Wclobbered -Wcomment\n -Wcompare-distinct-pointer-types\n--Wno-complain-wrong-lang\n+-Wno-complain-wrong-lang -Wconstant-logical-operand\n -Wconversion -Wno-coverage-mismatch -Wno-cpp\n -Wdangling-else -Wdangling-pointer -Wdangling-pointer=@var{n}\n -Wdate-time\n@@ -10647,6 +10647,22 @@ extern int a;\n if (a < 0 && a < 0) @{ @dots{} @}\n @end smallexample\n \n+@opindex Wconstant-logical-operand\n+@opindex Wno-constant-logical-operand\n+@item -Wconstant-logical-operand\n+Warn about another case of suspicious uses of logical operators in\n+expressions, when neither operand of a logical operator is boolean\n+and one of the operands is (or folds into) a constant other than 0 or 1,\n+or enumerator with value 1 if the enumeral type contains enumerators with\n+values other than 0 or 1.\n+In such case the warning will suggest using corresponding bitwise operator.\n+@smallexample\n+extern int a;\n+if (a && 64) @{ @dots{} @}\n+@end smallexample\n+If the warning is a false positive, one can clarify the code by using\n+e.g. @code{a && 64 != 0} instead.\n+\n @opindex Wlogical-not-parentheses\n @opindex Wno-logical-not-parentheses\n @item -Wlogical-not-parentheses\n--- gcc/c-family/c.opt.jj\t2026-04-30 10:18:08.247786966 +0200\n+++ gcc/c-family/c.opt\t2026-04-30 20:14:14.864156018 +0200\n@@ -595,6 +595,10 @@ Wconditionally-supported\n C++ ObjC++ Var(warn_conditionally_supported) Warning\n Warn for conditionally-supported constructs.\n \n+Wconstant-logical-operand\n+C ObjC C++ ObjC++ Var(warn_constant_logical_operand) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)\n+Warn for constant operands of logical operators other than 0 or 1.\n+\n Wconversion\n C ObjC C++ ObjC++ Var(warn_conversion) Warning\n Warn for implicit type conversions that may change a value.\n--- gcc/c-family/c.opt.urls.jj\t2026-04-30 10:18:08.248786948 +0200\n+++ gcc/c-family/c.opt.urls\t2026-04-30 20:14:14.865118139 +0200\n@@ -415,6 +415,9 @@ UrlSuffix(gcc/Warning-Options.html#index\n Wconditionally-supported\n UrlSuffix(gcc/C_002b_002b-Dialect-Options.html#index-Wconditionally-supported)\n \n+Wconstant-logical-operand\n+UrlSuffix(gcc/Warning-Options.html#index-Wconstant-logical-operand)\n+\n Wconversion\n UrlSuffix(gcc/Warning-Options.html#index-Wconversion) LangUrlSuffix_Fortran(gfortran/Error-and-Warning-Options.html#index-Wconversion)\n \n--- gcc/c/c-typeck.cc.jj\t2026-04-30 10:18:08.260786737 +0200\n+++ gcc/c/c-typeck.cc\t2026-04-30 21:18:33.663623866 +0200\n@@ -5112,13 +5112,15 @@ char_type_p (tree type)\n in the input. CODE, a tree_code, specifies the binary operator, and\n ARG1 and ARG2 are the operands. In addition to constructing the\n expression, we check for operands that were written with other binary\n- operators in a way that is likely to confuse the user.\n+ operators in a way that is likely to confuse the user. ORIG_ARG1 is\n+ the original first operand for TRUTH_{AND,OR}IF_EXPR before it is\n+ converted to truth value, otherwise NULL_TREE.\n \n LOCATION is the location of the binary operator. */\n \n struct c_expr\n parser_build_binary_op (location_t location, enum tree_code code,\n-\t\t\tstruct c_expr arg1, struct c_expr arg2)\n+\t\t\tstruct c_expr arg1, struct c_expr arg2, tree orig_arg1)\n {\n struct c_expr result;\n result.m_decimal = 0;\n@@ -5163,6 +5165,55 @@ parser_build_binary_op (location_t locat\n warn_logical_operator (location, code, TREE_TYPE (result.value),\n \t\t\t code1, arg1.value, code2, arg2.value);\n \n+ if (warn_constant_logical_operand\n+ && (code == TRUTH_ANDIF_EXPR || code == TRUTH_ORIF_EXPR)\n+ && (TREE_CODE (type1) == INTEGER_TYPE\n+\t || TREE_CODE (type1) == ENUMERAL_TYPE\n+\t || TREE_CODE (type1) == BITINT_TYPE)\n+ && (TREE_CODE (type2) == INTEGER_TYPE\n+\t || TREE_CODE (type2) == ENUMERAL_TYPE\n+\t || TREE_CODE (type2) == BITINT_TYPE))\n+ {\n+ const char *name = code == TRUTH_ANDIF_EXPR ? \"&&\" : \"||\";\n+ if (orig_arg1 == NULL_TREE)\n+\torig_arg1 = arg1.value;\n+ auto enum_other_than_0_1 = [] (tree type) {\n+\tif (TREE_CODE (type) != ENUMERAL_TYPE)\n+\t return false;\n+\tfor (tree l = TYPE_VALUES (type); l; l = TREE_CHAIN (l))\n+\t {\n+\t tree v = DECL_INITIAL (TREE_VALUE (l));\n+\t if (!integer_zerop (v) && !integer_onep (v))\n+\t return true;\n+\t }\n+\treturn false;\n+ };\n+ if (TREE_CODE (arg2.value) == INTEGER_CST\n+\t && !integer_zerop (arg2.value)\n+\t && (!integer_onep (arg2.value) || enum_other_than_0_1 (type2)))\n+\t{\n+\t gcc_rich_location richloc (location);\n+\t richloc.add_fixit_replace (name + 1);\n+\t auto_diagnostic_group d;\n+\t if (warning_at (location, OPT_Wconstant_logical_operand,\n+\t\t\t \"use of logical %qs with constant operand %qE\",\n+\t\t\t name, arg2.value))\n+\t inform (&richloc, \"use %qs for bitwise operation\", name + 1);\n+\t}\n+ else if (TREE_CODE (orig_arg1) == INTEGER_CST\n+\t && !integer_zerop (orig_arg1)\n+\t && (!integer_onep (orig_arg1) || enum_other_than_0_1 (type1)))\n+\t{\n+\t gcc_rich_location richloc (location);\n+\t richloc.add_fixit_replace (name + 1);\n+\t auto_diagnostic_group d;\n+\t if (warning_at (location, OPT_Wconstant_logical_operand,\n+\t\t\t \"use of logical %qs with constant operand %qE\",\n+\t\t\t name, orig_arg1))\n+\t inform (&richloc, \"use %qs for bitwise operation\", name + 1);\n+\t}\n+ }\n+\n if (warn_tautological_compare)\n {\n tree lhs = arg1.value;\n--- gcc/c/c-parser.cc.jj\t2026-04-30 10:18:13.802689121 +0200\n+++ gcc/c/c-parser.cc\t2026-04-30 20:14:14.869155933 +0200\n@@ -10304,6 +10304,9 @@ c_parser_binary_expression (c_parser *pa\n location_t loc;\n /* The sizeof argument if expr.original_code == {PAREN_,}SIZEOF_EXPR. */\n tree sizeof_arg;\n+ /* The original expr.value before c_objc_common_truthvalue_conversion\n+ for TRUTH_{AND,OR}*_EXPR lhs operands. */\n+ tree orig_expr;\n } stack[NUM_PRECS];\n int sp;\n /* Location of the binary operator. */\n@@ -10399,7 +10402,9 @@ c_parser_binary_expression (c_parser *pa\n stack[sp - 1].expr = parser_build_binary_op (stack[sp].loc,\t \\\n \t\t\t\t\t\t stack[sp].op,\t \\\n \t\t\t\t\t\t stack[sp - 1].expr,\t \\\n-\t\t\t\t\t\t stack[sp].expr);\t \\\n+\t\t\t\t\t\t stack[sp].expr,\t \\\n+\t\t\t\t\t\t stack[sp - 1].orig_expr); \\\n+ stack[sp - 1].orig_expr = NULL_TREE;\t\t\t\t \\\n sp--;\t\t\t\t\t\t\t\t \\\n } while (0)\n gcc_assert (!after || c_dialect_objc ());\n@@ -10407,6 +10412,7 @@ c_parser_binary_expression (c_parser *pa\n stack[0].expr = c_parser_cast_expression (parser, after);\n stack[0].prec = PREC_NONE;\n stack[0].sizeof_arg = c_last_sizeof_arg;\n+ stack[0].orig_expr = NULL_TREE;\n sp = 0;\n while (true)\n {\n@@ -10505,6 +10511,7 @@ c_parser_binary_expression (c_parser *pa\n \t stack[sp].expr\n \t = convert_lvalue_to_rvalue (stack[sp].loc,\n \t\t\t\t\tstack[sp].expr, true, true);\n+\t stack[sp].orig_expr = stack[sp].expr.value;\n \t stack[sp].expr.value = c_objc_common_truthvalue_conversion\n \t (stack[sp].loc, default_conversion (stack[sp].expr.value));\n \t c_inhibit_evaluation_warnings += (stack[sp].expr.value\n@@ -10516,6 +10523,7 @@ c_parser_binary_expression (c_parser *pa\n \t stack[sp].expr\n \t = convert_lvalue_to_rvalue (stack[sp].loc,\n \t\t\t\t\tstack[sp].expr, true, true);\n+\t stack[sp].orig_expr = stack[sp].expr.value;\n \t stack[sp].expr.value = c_objc_common_truthvalue_conversion\n \t (stack[sp].loc, default_conversion (stack[sp].expr.value));\n \t c_inhibit_evaluation_warnings += (stack[sp].expr.value\n@@ -10531,6 +10539,7 @@ c_parser_binary_expression (c_parser *pa\n stack[sp].prec = oprec;\n stack[sp].op = ocode;\n stack[sp].sizeof_arg = c_last_sizeof_arg;\n+ stack[sp].orig_expr = NULL_TREE;\n }\n out:\n while (sp > 0)\n--- gcc/c/c-tree.h.jj\t2026-04-30 10:18:13.803689103 +0200\n+++ gcc/c/c-tree.h\t2026-04-30 20:14:14.870460631 +0200\n@@ -890,7 +890,7 @@ extern struct c_expr parser_build_unary_\n \t\t\t\t\t struct c_expr);\n extern struct c_expr parser_build_binary_op (location_t,\n \t\t\t\t\t enum tree_code, struct c_expr,\n-\t\t\t\t\t struct c_expr);\n+\t\t\t\t\t struct c_expr, tree);\n extern tree build_conditional_expr (location_t, tree, bool, tree, tree,\n \t\t\t\t location_t, tree, tree, location_t);\n extern tree build_compound_expr (location_t, tree, tree);\n--- gcc/cp/typeck.cc.jj\t2026-04-30 10:18:08.342785292 +0200\n+++ gcc/cp/typeck.cc\t2026-04-30 21:18:00.423192892 +0200\n@@ -5953,6 +5953,53 @@ cp_build_binary_op (const op_location_t\n \t return cp_build_binary_op (location, code, op0, op1, complain);\n \t}\n \n+ if (warn_constant_logical_operand\n+\t && (complain & tf_warning)\n+\t && (code0 == INTEGER_TYPE || code0 == ENUMERAL_TYPE)\n+\t && (code1 == INTEGER_TYPE || code1 == ENUMERAL_TYPE))\n+\t{\n+\t tree cop0 = fold_for_warn (op0), cop1 = fold_for_warn (op1);\n+\t const char *name\n+\t = ((code == TRUTH_ANDIF_EXPR || code == TRUTH_AND_EXPR)\n+\t ? \"&&\" : \"||\");\n+\t auto enum_other_than_0_1 = [] (tree type) {\n+\t if (TREE_CODE (type) != ENUMERAL_TYPE)\n+\t return false;\n+\t for (tree l = TYPE_VALUES (type); l; l = TREE_CHAIN (l))\n+\t {\n+\t\ttree v = DECL_INITIAL (TREE_VALUE (l));\n+\t\tif (!integer_zerop (v) && !integer_onep (v))\n+\t\t return true;\n+\t }\n+\t return false;\n+\t };\n+\t if (TREE_CODE (cop1) == INTEGER_CST\n+\t && !integer_zerop (cop1)\n+\t && (!integer_onep (cop1) || enum_other_than_0_1 (orig_type1)))\n+\t {\n+\t gcc_rich_location richloc (location);\n+\t richloc.add_fixit_replace (location.m_operator_loc, name + 1);\n+\t auto_diagnostic_group d;\n+\t if (warning_at (location, OPT_Wconstant_logical_operand,\n+\t\t\t \"use of logical %qs with constant operand %qE\",\n+\t\t\t name, cop1))\n+\t\tinform (&richloc, \"use %qs for bitwise operation\", name + 1);\n+\t }\n+\t else if (TREE_CODE (cop0) == INTEGER_CST\n+\t\t && !integer_zerop (cop0)\n+\t\t && (!integer_onep (cop0)\n+\t\t || enum_other_than_0_1 (orig_type0)))\n+\t {\n+\t gcc_rich_location richloc (location);\n+\t richloc.add_fixit_replace (location.m_operator_loc, name + 1);\n+\t auto_diagnostic_group d;\n+\t if (warning_at (location, OPT_Wconstant_logical_operand,\n+\t\t\t \"use of logical %qs with constant operand %qE\",\n+\t\t\t name, cop0))\n+\t\tinform (&richloc, \"use %qs for bitwise operation\", name + 1);\n+\t }\n+\t}\n+\n result_type = boolean_type_node;\n break;\n \n--- gcc/testsuite/c-c++-common/Wconstant-logical-operand-1.c.jj\t2026-04-30 20:14:14.871996788 +0200\n+++ gcc/testsuite/c-c++-common/Wconstant-logical-operand-1.c\t2026-04-30 21:23:09.467902519 +0200\n@@ -0,0 +1,106 @@\n+/* PR c++/125081 */\n+/* { dg-do compile } */\n+/* { dg-options \"-std=c23\" { target c } } */\n+/* { dg-additional-options \"-Wconstant-logical-operand\" } */\n+\n+void foo (int);\n+enum A { B, C };\n+enum D { E, F, G, H, I };\n+\n+void\n+bar (int x, bool y)\n+{\n+ if (x && 64)\t/* { dg-warning \"use of logical '\\\\\\&\\\\\\&' with constant operand '64'\" } */\n+ foo (1);\t/* { dg-message \"note: use '\\\\\\&' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (128 && x)\t/* { dg-warning \"use of logical '\\\\\\&\\\\\\&' with constant operand '128'\" } */\n+ foo (2);\t/* { dg-message \"note: use '\\\\\\&' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (x && 1)\n+ foo (3);\n+ if (1 && x)\n+ foo (4);\n+ if (x && 0)\n+ foo (5);\n+ if (0 && x)\n+ foo (6);\n+ if (x || 32)\t/* { dg-warning \"use of logical '\\\\\\|\\\\\\|' with constant operand '32'\" } */\n+ foo (7);\t/* { dg-message \"note: use '\\\\\\|' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (256 || x)\t/* { dg-warning \"use of logical '\\\\\\|\\\\\\|' with constant operand '256'\" } */\n+ foo (8);\t/* { dg-message \"note: use '\\\\\\|' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (x || 1)\n+ foo (9);\n+ if (1 || x)\n+ foo (10);\n+ if (x || 0)\n+ foo (11);\n+ if (0 || x)\n+ foo (12);\n+ if (y && 64)\n+ foo (13);\n+ if (128 && y)\n+ foo (14);\n+ if (y || 32)\n+ foo (15);\n+ if (256 || y)\n+ foo (16);\n+ if (x && B)\n+ foo (17);\n+ if (B && x)\n+ foo (18);\n+ if (x && C)\n+ foo (19);\n+ if (C && x)\n+ foo (20);\n+ if (x && E)\n+ foo (21);\n+ if (E && x)\n+ foo (22);\n+ if (x && F)\t/* { dg-warning \"use of logical '\\\\\\&\\\\\\&' with constant operand '\\[1F]'\" } */\n+ foo (23);\t/* { dg-message \"note: use '\\\\\\&' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (F && x)\t/* { dg-warning \"use of logical '\\\\\\&\\\\\\&' with constant operand '\\[1F]'\" } */\n+ foo (24);\t/* { dg-message \"note: use '\\\\\\&' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (x && G)\t/* { dg-warning \"use of logical '\\\\\\&\\\\\\&' with constant operand '\\[2G]'\" } */\n+ foo (25);\t/* { dg-message \"note: use '\\\\\\&' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (G && x)\t/* { dg-warning \"use of logical '\\\\\\&\\\\\\&' with constant operand '\\[2G]'\" } */\n+ foo (26);\t/* { dg-message \"note: use '\\\\\\&' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (x || B)\n+ foo (27);\n+ if (B || x)\n+ foo (28);\n+ if (x || C)\n+ foo (29);\n+ if (C || x)\n+ foo (30);\n+ if (x || E)\n+ foo (31);\n+ if (E || x)\n+ foo (32);\n+ if (x || F)\t/* { dg-warning \"use of logical '\\\\\\|\\\\\\|' with constant operand '\\[1F]'\" } */\n+ foo (33);\t/* { dg-message \"note: use '\\\\\\|' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (F || x)\t/* { dg-warning \"use of logical '\\\\\\|\\\\\\|' with constant operand '\\[1F]'\" } */\n+ foo (34);\t/* { dg-message \"note: use '\\\\\\|' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (x || G)\t/* { dg-warning \"use of logical '\\\\\\|\\\\\\|' with constant operand '\\[2G]'\" } */\n+ foo (35);\t/* { dg-message \"note: use '\\\\\\|' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (G || x)\t/* { dg-warning \"use of logical '\\\\\\|\\\\\\|' with constant operand '\\[2G]'\" } */\n+ foo (36);\t/* { dg-message \"note: use '\\\\\\|' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+}\n+\n+void\n+baz (int x, bool y)\n+{\n+ if (x && 63 + 1)\t/* { dg-warning \"use of logical '\\\\\\&\\\\\\&' with constant operand '64'\" } */\n+ foo (1);\t\t/* { dg-message \"note: use '\\\\\\&' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (127 + 1 && x)\t/* { dg-warning \"use of logical '\\\\\\&\\\\\\&' with constant operand '128'\" } */\n+ foo (2);\t\t/* { dg-message \"note: use '\\\\\\&' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (x || 31 + 1)\t/* { dg-warning \"use of logical '\\\\\\|\\\\\\|' with constant operand '32'\" } */\n+ foo (7);\t\t/* { dg-message \"note: use '\\\\\\|' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (255 + 1 || x)\t/* { dg-warning \"use of logical '\\\\\\|\\\\\\|' with constant operand '256'\" } */\n+ foo (8);\t\t/* { dg-message \"note: use '\\\\\\|' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (y && 63 + 1)\n+ foo (13);\n+ if (127 + 1 && y)\n+ foo (14);\n+ if (y || 31 + 1)\n+ foo (15);\n+ if (255 + 1 || y)\n+ foo (16);\n+}\n--- gcc/testsuite/c-c++-common/Wconstant-logical-operand-2.c.jj\t2026-04-30 20:14:14.872108767 +0200\n+++ gcc/testsuite/c-c++-common/Wconstant-logical-operand-2.c\t2026-04-30 22:05:37.782226847 +0200\n@@ -0,0 +1,110 @@\n+/* PR c++/125081 */\n+/* { dg-do compile } */\n+/* { dg-options \"-std=c23\" { target c } } */\n+/* { dg-additional-options \"-Wall\" } */\n+\n+void foo (int);\n+enum A { B, C };\n+enum D { E, F, G, H, I };\n+\n+void\n+bar (int x, bool y)\n+{\n+ if (x && 64)\t/* { dg-warning \"use of logical '\\\\\\&\\\\\\&' with constant operand '64'\" } */\n+ foo (1);\t/* { dg-message \"note: use '\\\\\\&' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (128 && x)\t/* { dg-warning \"use of logical '\\\\\\&\\\\\\&' with constant operand '128'\" } */\n+ foo (2);\t/* { dg-message \"note: use '\\\\\\&' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (x && 1)\n+ foo (3);\n+ if (1 && x)\n+ foo (4);\n+ if (x && 0)\n+ foo (5);\n+ if (0 && x)\n+ foo (6);\n+ if (x || 32)\t/* { dg-warning \"use of logical '\\\\\\|\\\\\\|' with constant operand '32'\" } */\n+ foo (7);\t/* { dg-message \"note: use '\\\\\\|' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (256 || x)\t/* { dg-warning \"use of logical '\\\\\\|\\\\\\|' with constant operand '256'\" } */\n+ foo (8);\t/* { dg-message \"note: use '\\\\\\|' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (x || 1)\n+ foo (9);\n+ if (1 || x)\n+ foo (10);\n+ if (x || 0)\n+ foo (11);\n+ if (0 || x)\n+ foo (12);\n+ if (y && 64)\n+ foo (13);\n+ if (128 && y)\n+ foo (14);\n+ if (y || 32)\n+ foo (15);\n+ if (256 || y)\n+ foo (16);\n+ if (x && B)\n+ foo (17);\n+ if (B && x)\n+ foo (18);\n+ if (x && C)\n+ foo (19);\n+ if (C && x)\n+ foo (20);\n+ if (x && E)\n+ foo (21);\n+ if (E && x)\n+ foo (22);\n+ if (x && F)\t/* { dg-warning \"use of logical '\\\\\\&\\\\\\&' with constant operand '\\[1F]'\" } */\n+ foo (23);\t/* { dg-message \"note: use '\\\\\\&' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (F && x)\t/* { dg-warning \"use of logical '\\\\\\&\\\\\\&' with constant operand '\\[1F]'\" } */\n+ foo (24);\t/* { dg-message \"note: use '\\\\\\&' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (x && G)\t/* { dg-warning \"use of logical '\\\\\\&\\\\\\&' with constant operand '\\[2G]'\" } */\n+ foo (25);\t/* { dg-message \"note: use '\\\\\\&' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+\t\t/* { dg-warning \"enum constant in boolean context\" \"\" { target c++ } .-2 } */\n+ if (G && x)\t/* { dg-warning \"use of logical '\\\\\\&\\\\\\&' with constant operand '\\[2G]'\" } */\n+ foo (26);\t/* { dg-message \"note: use '\\\\\\&' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+\t\t/* { dg-warning \"enum constant in boolean context\" \"\" { target c++ } .-2 } */\n+ if (x || B)\n+ foo (27);\n+ if (B || x)\n+ foo (28);\n+ if (x || C)\n+ foo (29);\n+ if (C || x)\n+ foo (30);\n+ if (x || E)\n+ foo (31);\n+ if (E || x)\n+ foo (32);\n+ if (x || F)\t/* { dg-warning \"use of logical '\\\\\\|\\\\\\|' with constant operand '\\[1F]'\" } */\n+ foo (33);\t/* { dg-message \"note: use '\\\\\\|' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (F || x)\t/* { dg-warning \"use of logical '\\\\\\|\\\\\\|' with constant operand '\\[1F]'\" } */\n+ foo (34);\t/* { dg-message \"note: use '\\\\\\|' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (x || G)\t/* { dg-warning \"use of logical '\\\\\\|\\\\\\|' with constant operand '\\[2G]'\" } */\n+ foo (35);\t/* { dg-message \"note: use '\\\\\\|' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+\t\t/* { dg-warning \"enum constant in boolean context\" \"\" { target c++ } .-2 } */\n+ if (G || x)\t/* { dg-warning \"use of logical '\\\\\\|\\\\\\|' with constant operand '\\[2G]'\" } */\n+ foo (36);\t/* { dg-message \"note: use '\\\\\\|' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+\t\t/* { dg-warning \"enum constant in boolean context\" \"\" { target c++ } .-2 } */\n+}\n+\n+void\n+baz (int x, bool y)\n+{\n+ if (x && 63 + 1)\t/* { dg-warning \"use of logical '\\\\\\&\\\\\\&' with constant operand '64'\" } */\n+ foo (1);\t\t/* { dg-message \"note: use '\\\\\\&' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (127 + 1 && x)\t/* { dg-warning \"use of logical '\\\\\\&\\\\\\&' with constant operand '128'\" } */\n+ foo (2);\t\t/* { dg-message \"note: use '\\\\\\&' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (x || 31 + 1)\t/* { dg-warning \"use of logical '\\\\\\|\\\\\\|' with constant operand '32'\" } */\n+ foo (7);\t\t/* { dg-message \"note: use '\\\\\\|' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (255 + 1 || x)\t/* { dg-warning \"use of logical '\\\\\\|\\\\\\|' with constant operand '256'\" } */\n+ foo (8);\t\t/* { dg-message \"note: use '\\\\\\|' for bitwise operation\" \"\" { target *-*-* } .-1 } */\n+ if (y && 63 + 1)\n+ foo (13);\n+ if (127 + 1 && y)\n+ foo (14);\n+ if (y || 31 + 1)\n+ foo (15);\n+ if (255 + 1 || y)\n+ foo (16);\n+}\n","prefixes":[]}