On Thu, Jul 31, 2025 at 10:20:23PM +0200, Jakub Jelinek wrote:
> The following patch introduces a -Wkeyword-macro warning that clang has
> since 2014 to implement part of C++26 P2843R3 Preprocessing is never undefined
> paper.
Here is a tiny change to the patch, added an inline function to check for
what nodes were registered for -Wkeyword-macro purposes and use that instead
of repeating the same tests in 3 spots.
The rest is unchanged.
2025-08-01 Jakub Jelinek <ja...@redhat.com>
PR preprocessor/120778
gcc/
* doc/invoke.texi (Wkeyword-macro): Document.
gcc/c-family/
* c.opt (Wkeyword-macro): New option.
* c.opt.urls: Regenerate.
* c-common.h (cxx_dialect): Comment formatting fix.
* c-opts.cc (c_common_post_options): Default to
-Wkeyword-macro for C++26 if pedantic.
gcc/c/
* c-decl.cc (c_init_decl_processing): Mark cpp nodes corresponding
to keywords as NODE_WARN if warn_keyword_macro.
gcc/cp/
* lex.cc (cxx_init): Mark cpp nodes corresponding
to keywords, identifiers with special meaning and standard
attribute identifiers as NODE_WARN if warn_keyword_macro.
gcc/testsuite/
* gcc.dg/Wkeyword-macro-1.c: New test.
* gcc.dg/Wkeyword-macro-2.c: New test.
* gcc.dg/Wkeyword-macro-3.c: New test.
* gcc.dg/Wkeyword-macro-4.c: New test.
* gcc.dg/Wkeyword-macro-5.c: New test.
* gcc.dg/Wkeyword-macro-6.c: New test.
* gcc.dg/Wkeyword-macro-7.c: New test.
* gcc.dg/Wkeyword-macro-8.c: New test.
* gcc.dg/Wkeyword-macro-9.c: New test.
* g++.dg/warn/Wkeyword-macro-1.C: New test.
* g++.dg/warn/Wkeyword-macro-2.C: New test.
* g++.dg/warn/Wkeyword-macro-3.C: New test.
* g++.dg/warn/Wkeyword-macro-4.C: New test.
* g++.dg/warn/Wkeyword-macro-5.C: New test.
* g++.dg/warn/Wkeyword-macro-6.C: New test.
* g++.dg/warn/Wkeyword-macro-7.C: New test.
* g++.dg/warn/Wkeyword-macro-8.C: New test.
* g++.dg/warn/Wkeyword-macro-9.C: New test.
* g++.dg/warn/Wkeyword-macro-10.C: New test.
* g++.dg/opt/pr82577.C: Don't #define register to nothing for
C++17 and later. Instead define reg macro to nothing for C++17
and later or to register and use it instead of register.
* g++.dg/modules/atom-preamble-3.C: Add -Wno-keyword-macro to
dg-additional-options.
* g++.dg/template/sfinae17.C (static_assert): Rename macro to ...
(my_static_assert): ... this.
(main): Use my_static_assert instead of static_assert.
libcpp/
* include/cpplib.h (struct cpp_options): Add cpp_warn_keyword_macro.
(enum cpp_warning_reason): Add CPP_W_KEYWORD_MACRO enumerator.
(cpp_keyword_p): New inline function.
* directives.cc (do_undef): Support -Wkeyword-macro diagnostics.
* macro.cc (warn_of_redefinition): Ignore NODE_WARN flag on nodes
registered for -Wkeyword-macro.
(_cpp_create_definition): Support -Wkeyword-macro diagnostics.
Formatting fixes.
--- gcc/doc/invoke.texi.jj 2025-07-30 13:40:57.360534474 +0200
+++ gcc/doc/invoke.texi 2025-07-31 17:56:30.931003369 +0200
@@ -388,6 +388,7 @@ Objective-C and Objective-C++ Dialects}.
-Winit-self -Winline -Wno-int-conversion -Wint-in-bool-context
-Wno-int-to-pointer-cast -Wno-invalid-memory-model
-Winvalid-pch -Winvalid-utf8 -Wno-unicode -Wjump-misses-init
+-Wkeyword-macro
-Wlarger-than=@var{byte-size} -Wleading-whitespace=@var{kind}
-Wlogical-not-parentheses -Wlogical-op
-Wlong-long -Wno-lto-type-mismatch -Wmain -Wmaybe-uninitialized
@@ -10398,6 +10399,14 @@ Do not warn if certain built-in macros a
warnings for redefinition of @code{__TIMESTAMP__}, @code{__TIME__},
@code{__DATE__}, @code{__FILE__}, and @code{__BASE_FILE__}.
+@opindex Wkeyword-macro
+@opindex Wno-keyword-macro
+@item -Wkeyword-macro
+Warn if a keyword is defined as a macro or undefined.
+For C++ identifiers with special meaning or standard attribute identifiers
+are diagnosed as well. This warning is enabled by default for C++26
+if @code{-Wpedantic} and emits a pedwarn in that case.
+
@opindex Wfree-labels
@opindex Wno-free-labels
@item -Wfree-labels @r{(C and Objective-C only)}
--- gcc/c-family/c.opt.jj 2025-07-31 10:40:31.808618336 +0200
+++ gcc/c-family/c.opt 2025-07-31 13:36:18.542412606 +0200
@@ -964,6 +964,10 @@ Enum(warn_leading_whitespace_kind) Strin
EnumValue
Enum(warn_leading_whitespace_kind) String(blanks) Value(3)
+Wkeyword-macro
+C ObjC C++ ObjC++ CPP(cpp_warn_keyword_macro) CppReason(CPP_W_KEYWORD_MACRO)
Var(warn_keyword_macro) Init(0) Warning
+Warn about defining or undefining macros with identifiers equal to keywords
(or for C++ conditional keywords or standard attribute names).
+
Wleading-whitespace=
C ObjC C++ ObjC++ CPP(cpp_warn_leading_whitespace)
CppReason(CPP_W_LEADING_WHITESPACE) Enum(warn_leading_whitespace_kind) Joined
RejectNegative Var(warn_leading_whitespace) Init(0) Warning
Warn about leading whitespace style issues on lines except when in raw string
literals.
--- gcc/c-family/c.opt.urls.jj 2025-07-11 19:01:25.412538022 +0200
+++ gcc/c-family/c.opt.urls 2025-07-31 17:57:23.100322691 +0200
@@ -508,6 +508,9 @@ UrlSuffix(gcc/Warning-Options.html#index
Wjump-misses-init
UrlSuffix(gcc/Warning-Options.html#index-Wjump-misses-init)
+Wkeyword-macro
+UrlSuffix(gcc/Warning-Options.html#index-Wkeyword-macro)
+
Wleading-whitespace=
UrlSuffix(gcc/Warning-Options.html#index-Wleading-whitespace_003d)
--- gcc/c-family/c-common.h.jj 2025-07-31 10:40:31.789618585 +0200
+++ gcc/c-family/c-common.h 2025-07-31 13:36:18.586412029 +0200
@@ -747,7 +747,7 @@ enum cxx_dialect {
cxx26
};
-/* The C++ dialect being used. C++98 is the default. */
+/* The C++ dialect being used. C++17 is the default. */
extern enum cxx_dialect cxx_dialect;
/* Maximum template instantiation depth. This limit is rather
--- gcc/c-family/c-opts.cc.jj 2025-07-31 10:40:31.790618572 +0200
+++ gcc/c-family/c-opts.cc 2025-07-31 13:36:18.567412279 +0200
@@ -959,6 +959,15 @@ c_common_post_options (const char **pfil
if (warn_enum_compare == -1)
warn_enum_compare = c_dialect_cxx () ? 1 : 0;
+ /* For C++26 default to -Wkeyword-macro if -Wpedantic. */
+ if (cxx_dialect >= cxx26 && pedantic)
+ {
+ SET_OPTION_IF_UNSET (&global_options, &global_options_set,
+ warn_keyword_macro, 1);
+ if (warn_keyword_macro)
+ cpp_opts->cpp_warn_keyword_macro = warn_keyword_macro;
+ }
+
/* -Wpacked-bitfield-compat is on by default for the C languages. The
warning is issued in stor-layout.cc which is not part of the front-end so
we need to selectively turn it on here. */
--- gcc/c/c-decl.cc.jj 2025-07-27 23:31:09.153014353 +0200
+++ gcc/c/c-decl.cc 2025-07-31 14:36:55.400715867 +0200
@@ -4825,6 +4825,30 @@ c_init_decl_processing (void)
make_fname_decl = c_make_fname_decl;
start_fname_decls ();
+
+ if (warn_keyword_macro)
+ {
+ for (unsigned int i = 0; i < num_c_common_reswords; ++i)
+ /* For C register keywords which don't start with underscore
+ or start with just single underscore. Furthermore, most of ObjC
+ keywords are context sensitive, don't complain about those
+ either. */
+ if (c_common_reswords[i].word[0] == '_'
+ && c_common_reswords[i].word[1] == '_')
+ continue;
+ else if (c_common_reswords[i].disable
+ & (D_TRANSMEM | D_OBJC | D_CXX_OBJC))
+ continue;
+ else
+ {
+ tree id = get_identifier (c_common_reswords[i].word);
+ if (C_IS_RESERVED_WORD (id)
+ && C_RID_CODE (id) != RID_CXX_COMPAT_WARN)
+ cpp_lookup (parse_in,
+ (const unsigned char *) IDENTIFIER_POINTER (id),
+ IDENTIFIER_LENGTH (id))->flags |= NODE_WARN;
+ }
+ }
}
/* Create the VAR_DECL at LOC for __FUNCTION__ etc. ID is the name to
--- gcc/cp/lex.cc.jj 2025-07-31 10:40:31.823618138 +0200
+++ gcc/cp/lex.cc 2025-07-31 14:07:27.994888827 +0200
@@ -368,6 +368,67 @@ cxx_init (void)
cxx_init_decl_processing ();
+ if (warn_keyword_macro)
+ {
+ for (unsigned int i = 0; i < num_c_common_reswords; ++i)
+ /* For C++ none of the keywords in [lex.key] starts with underscore,
+ don't register anything like that. Furthermore, most of ObjC
+ keywords are context sensitive, don't complain about those
+ either. */
+ if (c_common_reswords[i].word[0] == '_')
+ continue;
+ else if (c_common_reswords[i].disable & (D_TRANSMEM | D_OBJC))
+ continue;
+ else
+ {
+ tree id = get_identifier (c_common_reswords[i].word);
+ if (IDENTIFIER_KEYWORD_P (id)
+ /* Don't register keywords with spaces. */
+ && IDENTIFIER_POINTER (id)[IDENTIFIER_LENGTH (id) - 1] != ' ')
+ cpp_lookup (parse_in,
+ (const unsigned char *) IDENTIFIER_POINTER (id),
+ IDENTIFIER_LENGTH (id))->flags |= NODE_WARN;
+ }
+ auto warn_on = [] (const char *name) {
+ cpp_lookup (parse_in, (const unsigned char *) name,
+ strlen (name))->flags |= NODE_WARN;
+ };
+ if (cxx_dialect >= cxx11)
+ {
+ warn_on ("final");
+ warn_on ("override");
+ warn_on ("noreturn");
+ if (cxx_dialect < cxx26)
+ warn_on ("carries_dependency");
+ }
+ if (cxx_dialect >= cxx14)
+ warn_on ("deprecated");
+ if (cxx_dialect >= cxx17)
+ {
+ warn_on ("fallthrough");
+ warn_on ("maybe_unused");
+ warn_on ("nodiscard");
+ }
+ if (cxx_dialect >= cxx20)
+ {
+ warn_on ("likely");
+ warn_on ("unlikely");
+ warn_on ("no_unique_address");
+ }
+ if (flag_modules)
+ {
+ warn_on ("import");
+ warn_on ("module");
+ }
+ if (cxx_dialect >= cxx23)
+ warn_on ("assume");
+ if (cxx_dialect >= cxx26)
+ {
+ warn_on ("replaceable_if_eligible");
+ warn_on ("trivially_relocatable_if_eligible");
+ }
+ }
+
if (c_common_init () == false)
{
input_location = saved_loc;
--- gcc/testsuite/gcc.dg/Wkeyword-macro-1.c.jj 2025-07-31 17:22:09.194003451
+0200
+++ gcc/testsuite/gcc.dg/Wkeyword-macro-1.c 2025-07-31 17:21:59.267135053
+0200
@@ -0,0 +1,62 @@
+// { dg-do preprocess }
+// { dg-options "-Wkeyword-macro -std=c23" }
+
+#define _Alignas 1 // { dg-warning "keyword '_Alignas'
defined as macro" }
+#define _Alignof 1 // { dg-warning "keyword '_Alignof'
defined as macro" }
+#define _Atomic 1 // { dg-warning "keyword '_Atomic'
defined as macro" }
+#define _BitInt 1 // { dg-warning "keyword '_BitInt'
defined as macro" }
+#define _Bool 1 // { dg-warning "keyword
'_Bool' defined as macro" }
+#define _Complex 1 // { dg-warning "keyword '_Complex'
defined as macro" }
+#define _Decimal128 1 // { dg-warning "keyword '_Decimal128'
defined as macro" }
+#define _Decimal32 1 // { dg-warning "keyword '_Decimal32'
defined as macro" }
+#define _Decimal64 1 // { dg-warning "keyword '_Decimal64'
defined as macro" }
+#define _Generic 1 // { dg-warning "keyword '_Generic'
defined as macro" }
+#define _Imaginary 1 // { dg-warning "keyword '_Imaginary'
defined as macro" }
+#define _Noreturn 1 // { dg-warning "keyword '_Noreturn'
defined as macro" }
+#define _Static_assert 1 // { dg-warning "keyword
'_Static_assert' defined as macro" }
+#define _Thread_local 1 // { dg-warning "keyword
'_Thread_local' defined as macro" }
+#define alignas 1 // { dg-warning "keyword 'alignas'
defined as macro" }
+#define alignof 1 // { dg-warning "keyword 'alignof'
defined as macro" }
+#define auto 1 // { dg-warning "keyword 'auto' defined
as macro" }
+#define bool 1 // { dg-warning "keyword 'bool' defined
as macro" }
+#define break 1 // { dg-warning "keyword
'break' defined as macro" }
+#define case 1 // { dg-warning "keyword 'case' defined
as macro" }
+#define char 1 // { dg-warning "keyword 'char' defined
as macro" }
+#define const 1 // { dg-warning "keyword
'const' defined as macro" }
+#define constexpr 1 // { dg-warning "keyword 'constexpr'
defined as macro" }
+#define continue 1 // { dg-warning "keyword 'continue'
defined as macro" }
+#define default 1 // { dg-warning "keyword 'default'
defined as macro" }
+#define do 1 // { dg-warning "keyword 'do' defined
as macro" }
+#define double 1 // { dg-warning "keyword 'double'
defined as macro" }
+#define else 1 // { dg-warning "keyword 'else' defined
as macro" }
+#define enum 1 // { dg-warning "keyword 'enum' defined
as macro" }
+#define extern 1 // { dg-warning "keyword 'extern'
defined as macro" }
+#define false 1 // { dg-warning "keyword
'false' defined as macro" }
+#define float 1 // { dg-warning "keyword
'float' defined as macro" }
+#define for 1 // { dg-warning "keyword 'for' defined
as macro" }
+#define goto 1 // { dg-warning "keyword 'goto' defined
as macro" }
+#define if 1 // { dg-warning "keyword 'if' defined
as macro" }
+#define inline 1 // { dg-warning "keyword 'inline'
defined as macro" }
+#define int 1 // { dg-warning "keyword 'int' defined
as macro" }
+#define long 1 // { dg-warning "keyword 'long' defined
as macro" }
+#define nullptr 1 // { dg-warning "keyword 'nullptr'
defined as macro" }
+#define register 1 // { dg-warning "keyword 'register'
defined as macro" }
+#define restrict 1 // { dg-warning "keyword 'restrict'
defined as macro" }
+#define return 1 // { dg-warning "keyword 'return'
defined as macro" }
+#define short 1 // { dg-warning "keyword
'short' defined as macro" }
+#define signed 1 // { dg-warning "keyword 'signed'
defined as macro" }
+#define sizeof 1 // { dg-warning "keyword 'sizeof'
defined as macro" }
+#define static 1 // { dg-warning "keyword 'static'
defined as macro" }
+#define static_assert 1 // { dg-warning "keyword
'static_assert' defined as macro" }
+#define struct 1 // { dg-warning "keyword 'struct'
defined as macro" }
+#define switch 1 // { dg-warning "keyword 'switch'
defined as macro" }
+#define thread_local 1 // { dg-warning "keyword 'thread_local'
defined as macro" }
+#define true 1 // { dg-warning "keyword 'true' defined
as macro" }
+#define typedef 1 // { dg-warning "keyword 'typedef'
defined as macro" }
+#define typeof 1 // { dg-warning "keyword 'typeof'
defined as macro" }
+#define typeof_unqual 1 // { dg-warning "keyword
'typeof_unqual' defined as macro" }
+#define union 1 // { dg-warning "keyword
'union' defined as macro" }
+#define unsigned 1 // { dg-warning "keyword 'unsigned'
defined as macro" }
+#define void 1 // { dg-warning "keyword 'void' defined
as macro" }
+#define volatile 1 // { dg-warning "keyword 'volatile'
defined as macro" }
+#define while 1 // { dg-warning "keyword
'while' defined as macro" }
--- gcc/testsuite/gcc.dg/Wkeyword-macro-2.c.jj 2025-07-31 17:18:48.530663590
+0200
+++ gcc/testsuite/gcc.dg/Wkeyword-macro-2.c 2025-07-31 17:23:07.496230556
+0200
@@ -0,0 +1,4 @@
+// { dg-do preprocess }
+// { dg-options "-std=c23" }
+
+#include "Wkeyword-macro-1.c"
--- gcc/testsuite/gcc.dg/Wkeyword-macro-3.c.jj 2025-07-31 17:29:29.780178046
+0200
+++ gcc/testsuite/gcc.dg/Wkeyword-macro-3.c 2025-07-31 17:30:36.555305193
+0200
@@ -0,0 +1,62 @@
+// { dg-do preprocess }
+// { dg-options "-Wkeyword-macro -std=c23" }
+
+#undef _Alignas // { dg-warning "undefining keyword
'_Alignas'" }
+#undef _Alignof // { dg-warning "undefining keyword
'_Alignof'" }
+#undef _Atomic // { dg-warning "undefining keyword '_Atomic'" }
+#undef _BitInt // { dg-warning "undefining keyword '_BitInt'" }
+#undef _Bool // { dg-warning "undefining keyword '_Bool'" }
+#undef _Complex // { dg-warning "undefining keyword
'_Complex'" }
+#undef _Decimal128 // { dg-warning "undefining keyword
'_Decimal128'" }
+#undef _Decimal32 // { dg-warning "undefining keyword
'_Decimal32'" }
+#undef _Decimal64 // { dg-warning "undefining keyword
'_Decimal64'" }
+#undef _Generic // { dg-warning "undefining keyword
'_Generic'" }
+#undef _Imaginary // { dg-warning "undefining keyword
'_Imaginary'" }
+#undef _Noreturn // { dg-warning "undefining keyword
'_Noreturn'" }
+#undef _Static_assert // { dg-warning "undefining keyword
'_Static_assert'" }
+#undef _Thread_local // { dg-warning "undefining keyword
'_Thread_local'" }
+#undef alignas // { dg-warning "undefining keyword 'alignas'" }
+#undef alignof // { dg-warning "undefining keyword 'alignof'" }
+#undef auto // { dg-warning "undefining keyword 'auto'" }
+#undef bool // { dg-warning "undefining keyword 'bool'" }
+#undef break // { dg-warning "undefining keyword 'break'" }
+#undef case // { dg-warning "undefining keyword 'case'" }
+#undef char // { dg-warning "undefining keyword 'char'" }
+#undef const // { dg-warning "undefining keyword 'const'" }
+#undef constexpr // { dg-warning "undefining keyword
'constexpr'" }
+#undef continue // { dg-warning "undefining keyword
'continue'" }
+#undef default // { dg-warning "undefining keyword 'default'" }
+#undef do // { dg-warning "undefining keyword 'do'" }
+#undef double // { dg-warning "undefining keyword 'double'" }
+#undef else // { dg-warning "undefining keyword 'else'" }
+#undef enum // { dg-warning "undefining keyword 'enum'" }
+#undef extern // { dg-warning "undefining keyword 'extern'" }
+#undef false // { dg-warning "undefining keyword 'false'" }
+#undef float // { dg-warning "undefining keyword 'float'" }
+#undef for // { dg-warning "undefining keyword 'for'" }
+#undef goto // { dg-warning "undefining keyword 'goto'" }
+#undef if // { dg-warning "undefining keyword 'if'" }
+#undef inline // { dg-warning "undefining keyword 'inline'" }
+#undef int // { dg-warning "undefining keyword 'int'" }
+#undef long // { dg-warning "undefining keyword 'long'" }
+#undef nullptr // { dg-warning "undefining keyword 'nullptr'" }
+#undef register // { dg-warning "undefining keyword
'register'" }
+#undef restrict // { dg-warning "undefining keyword
'restrict'" }
+#undef return // { dg-warning "undefining keyword 'return'" }
+#undef short // { dg-warning "undefining keyword 'short'" }
+#undef signed // { dg-warning "undefining keyword 'signed'" }
+#undef sizeof // { dg-warning "undefining keyword 'sizeof'" }
+#undef static // { dg-warning "undefining keyword 'static'" }
+#undef static_assert // { dg-warning "undefining keyword
'static_assert'" }
+#undef struct // { dg-warning "undefining keyword 'struct'" }
+#undef switch // { dg-warning "undefining keyword 'switch'" }
+#undef thread_local // { dg-warning "undefining keyword
'thread_local'" }
+#undef true // { dg-warning "undefining keyword 'true'" }
+#undef typedef // { dg-warning "undefining keyword 'typedef'" }
+#undef typeof // { dg-warning "undefining keyword 'typeof'" }
+#undef typeof_unqual // { dg-warning "undefining keyword
'typeof_unqual'" }
+#undef union // { dg-warning "undefining keyword 'union'" }
+#undef unsigned // { dg-warning "undefining keyword
'unsigned'" }
+#undef void // { dg-warning "undefining keyword 'void'" }
+#undef volatile // { dg-warning "undefining keyword
'volatile'" }
+#undef while // { dg-warning "undefining keyword 'while'" }
--- gcc/testsuite/gcc.dg/Wkeyword-macro-4.c.jj 2025-07-31 17:30:50.323125225
+0200
+++ gcc/testsuite/gcc.dg/Wkeyword-macro-4.c 2025-07-31 17:30:55.733054508
+0200
@@ -0,0 +1,4 @@
+// { dg-do preprocess }
+// { dg-options "-std=c23" }
+
+#include "Wkeyword-macro-3.c"
--- gcc/testsuite/gcc.dg/Wkeyword-macro-5.c.jj 2025-07-31 17:28:08.155245012
+0200
+++ gcc/testsuite/gcc.dg/Wkeyword-macro-5.c 2025-07-31 17:29:00.685558360
+0200
@@ -0,0 +1,47 @@
+// { dg-do preprocess }
+// { dg-options "-Wkeyword-macro -std=c17" }
+
+#define _Alignas 1 // { dg-warning "keyword '_Alignas'
defined as macro" }
+#define _Alignof 1 // { dg-warning "keyword '_Alignof'
defined as macro" }
+#define _Atomic 1 // { dg-warning "keyword '_Atomic'
defined as macro" }
+#define _Bool 1 // { dg-warning "keyword
'_Bool' defined as macro" }
+#define _Complex 1 // { dg-warning "keyword '_Complex'
defined as macro" }
+#define _Generic 1 // { dg-warning "keyword '_Generic'
defined as macro" }
+#define _Imaginary 1 // { dg-warning "keyword '_Imaginary'
defined as macro" }
+#define _Noreturn 1 // { dg-warning "keyword '_Noreturn'
defined as macro" }
+#define _Static_assert 1 // { dg-warning "keyword
'_Static_assert' defined as macro" }
+#define _Thread_local 1 // { dg-warning "keyword
'_Thread_local' defined as macro" }
+#define auto 1 // { dg-warning "keyword 'auto' defined
as macro" }
+#define break 1 // { dg-warning "keyword
'break' defined as macro" }
+#define case 1 // { dg-warning "keyword 'case' defined
as macro" }
+#define char 1 // { dg-warning "keyword 'char' defined
as macro" }
+#define const 1 // { dg-warning "keyword
'const' defined as macro" }
+#define continue 1 // { dg-warning "keyword 'continue'
defined as macro" }
+#define default 1 // { dg-warning "keyword 'default'
defined as macro" }
+#define do 1 // { dg-warning "keyword 'do' defined
as macro" }
+#define double 1 // { dg-warning "keyword 'double'
defined as macro" }
+#define else 1 // { dg-warning "keyword 'else' defined
as macro" }
+#define enum 1 // { dg-warning "keyword 'enum' defined
as macro" }
+#define extern 1 // { dg-warning "keyword 'extern'
defined as macro" }
+#define float 1 // { dg-warning "keyword
'float' defined as macro" }
+#define for 1 // { dg-warning "keyword 'for' defined
as macro" }
+#define goto 1 // { dg-warning "keyword 'goto' defined
as macro" }
+#define if 1 // { dg-warning "keyword 'if' defined
as macro" }
+#define inline 1 // { dg-warning "keyword 'inline'
defined as macro" }
+#define int 1 // { dg-warning "keyword 'int' defined
as macro" }
+#define long 1 // { dg-warning "keyword 'long' defined
as macro" }
+#define register 1 // { dg-warning "keyword 'register'
defined as macro" }
+#define restrict 1 // { dg-warning "keyword 'restrict'
defined as macro" }
+#define return 1 // { dg-warning "keyword 'return'
defined as macro" }
+#define short 1 // { dg-warning "keyword
'short' defined as macro" }
+#define signed 1 // { dg-warning "keyword 'signed'
defined as macro" }
+#define sizeof 1 // { dg-warning "keyword 'sizeof'
defined as macro" }
+#define static 1 // { dg-warning "keyword 'static'
defined as macro" }
+#define struct 1 // { dg-warning "keyword 'struct'
defined as macro" }
+#define switch 1 // { dg-warning "keyword 'switch'
defined as macro" }
+#define typedef 1 // { dg-warning "keyword 'typedef'
defined as macro" }
+#define union 1 // { dg-warning "keyword
'union' defined as macro" }
+#define unsigned 1 // { dg-warning "keyword 'unsigned'
defined as macro" }
+#define void 1 // { dg-warning "keyword 'void' defined
as macro" }
+#define volatile 1 // { dg-warning "keyword 'volatile'
defined as macro" }
+#define while 1 // { dg-warning "keyword
'while' defined as macro" }
--- gcc/testsuite/gcc.dg/Wkeyword-macro-6.c.jj 2025-07-31 17:29:12.493404013
+0200
+++ gcc/testsuite/gcc.dg/Wkeyword-macro-6.c 2025-07-31 17:29:18.546324890
+0200
@@ -0,0 +1,4 @@
+// { dg-do preprocess }
+// { dg-options "-std=c17" }
+
+#include "Wkeyword-macro-5.c"
--- gcc/testsuite/gcc.dg/Wkeyword-macro-7.c.jj 2025-07-31 17:31:06.208917571
+0200
+++ gcc/testsuite/gcc.dg/Wkeyword-macro-7.c 2025-07-31 17:32:00.181212070
+0200
@@ -0,0 +1,47 @@
+// { dg-do preprocess }
+// { dg-options "-Wkeyword-macro -std=c17" }
+
+#undef _Alignas // { dg-warning "undefining keyword
'_Alignas'" }
+#undef _Alignof // { dg-warning "undefining keyword
'_Alignof'" }
+#undef _Atomic // { dg-warning "undefining keyword '_Atomic'" }
+#undef _Bool // { dg-warning "undefining keyword '_Bool'" }
+#undef _Complex // { dg-warning "undefining keyword
'_Complex'" }
+#undef _Generic // { dg-warning "undefining keyword
'_Generic'" }
+#undef _Imaginary // { dg-warning "undefining keyword
'_Imaginary'" }
+#undef _Noreturn // { dg-warning "undefining keyword
'_Noreturn'" }
+#undef _Static_assert // { dg-warning "undefining keyword
'_Static_assert'" }
+#undef _Thread_local // { dg-warning "undefining keyword
'_Thread_local'" }
+#undef auto // { dg-warning "undefining keyword 'auto'" }
+#undef break // { dg-warning "undefining keyword 'break'" }
+#undef case // { dg-warning "undefining keyword 'case'" }
+#undef char // { dg-warning "undefining keyword 'char'" }
+#undef const // { dg-warning "undefining keyword 'const'" }
+#undef continue // { dg-warning "undefining keyword
'continue'" }
+#undef default // { dg-warning "undefining keyword 'default'" }
+#undef do // { dg-warning "undefining keyword 'do'" }
+#undef double // { dg-warning "undefining keyword 'double'" }
+#undef else // { dg-warning "undefining keyword 'else'" }
+#undef enum // { dg-warning "undefining keyword 'enum'" }
+#undef extern // { dg-warning "undefining keyword 'extern'" }
+#undef float // { dg-warning "undefining keyword 'float'" }
+#undef for // { dg-warning "undefining keyword 'for'" }
+#undef goto // { dg-warning "undefining keyword 'goto'" }
+#undef if // { dg-warning "undefining keyword 'if'" }
+#undef inline // { dg-warning "undefining keyword 'inline'" }
+#undef int // { dg-warning "undefining keyword 'int'" }
+#undef long // { dg-warning "undefining keyword 'long'" }
+#undef register // { dg-warning "undefining keyword
'register'" }
+#undef restrict // { dg-warning "undefining keyword
'restrict'" }
+#undef return // { dg-warning "undefining keyword 'return'" }
+#undef short // { dg-warning "undefining keyword 'short'" }
+#undef signed // { dg-warning "undefining keyword 'signed'" }
+#undef sizeof // { dg-warning "undefining keyword 'sizeof'" }
+#undef static // { dg-warning "undefining keyword 'static'" }
+#undef struct // { dg-warning "undefining keyword 'struct'" }
+#undef switch // { dg-warning "undefining keyword 'switch'" }
+#undef typedef // { dg-warning "undefining keyword 'typedef'" }
+#undef union // { dg-warning "undefining keyword 'union'" }
+#undef unsigned // { dg-warning "undefining keyword
'unsigned'" }
+#undef void // { dg-warning "undefining keyword 'void'" }
+#undef volatile // { dg-warning "undefining keyword
'volatile'" }
+#undef while // { dg-warning "undefining keyword 'while'" }
--- gcc/testsuite/gcc.dg/Wkeyword-macro-8.c.jj 2025-07-31 17:39:30.100330917
+0200
+++ gcc/testsuite/gcc.dg/Wkeyword-macro-8.c 2025-07-31 17:39:35.178264540
+0200
@@ -0,0 +1,4 @@
+// { dg-do preprocess }
+// { dg-options "-std=c17" }
+
+#include "Wkeyword-macro-7.c"
--- gcc/testsuite/gcc.dg/Wkeyword-macro-9.c.jj 2025-07-31 17:40:09.893810755
+0200
+++ gcc/testsuite/gcc.dg/Wkeyword-macro-9.c 2025-07-31 17:41:46.891542847
+0200
@@ -0,0 +1,15 @@
+// { dg-do preprocess }
+// { dg-options "-Wkeyword-macro" }
+
+#undef for // { dg-warning "undefining keyword
'for'" }
+#define for for // { dg-warning "keyword 'for'
defined as macro" }
+#undef for // { dg-warning "undefining keyword
'for'" }
+#define while do // { dg-warning "keyword 'while'
defined as macro" }
+#define while do // { dg-warning "keyword 'while'
defined as macro" }
+#define while for // { dg-warning "keyword 'while'
defined as macro" }
+ // { dg-warning "'while' redefined" ""
{ target *-*-* } .-1 }
+#undef while // { dg-warning "undefining keyword
'while'" }
+#define while while // { dg-warning "keyword 'while'
defined as macro" }
+#define inline // { dg-warning "keyword 'inline'
defined as macro" }
+#undef inline // { dg-warning "undefining keyword
'inline'" }
+#define inline __inline__ __attribute__((__always_inline__)) // { dg-warning
"keyword 'inline' defined as macro" }
--- gcc/testsuite/g++.dg/warn/Wkeyword-macro-1.C.jj 2025-07-31
14:02:12.783022267 +0200
+++ gcc/testsuite/g++.dg/warn/Wkeyword-macro-1.C 2025-07-31
17:24:11.762378602 +0200
@@ -0,0 +1,112 @@
+// C++26 P2843R3 - Preprocessing is never undefined
+// [cpp.replace.general]/9
+// { dg-do preprocess }
+// { dg-options "-pedantic-errors" }
+// { dg-additional-options "-fmodules" { target c++20 } }
+
+// [lex.key]
+#define alignas 1 // { dg-error "keyword 'alignas'
defined as macro" "" { target c++26 } }
+#define alignof 1 // { dg-error "keyword 'alignof'
defined as macro" "" { target c++26 } }
+#define asm 1 // { dg-error "keyword 'asm' defined as
macro" "" { target c++26 } }
+#define auto 1 // { dg-error "keyword 'auto' defined
as macro" "" { target c++26 } }
+#define bool 1 // { dg-error "keyword 'bool' defined
as macro" "" { target c++26 } }
+#define break 1 // { dg-error "keyword 'break'
defined as macro" "" { target c++26 } }
+#define case 1 // { dg-error "keyword 'case' defined
as macro" "" { target c++26 } }
+#define catch 1 // { dg-error "keyword 'catch'
defined as macro" "" { target c++26 } }
+#define char 1 // { dg-error "keyword 'char' defined
as macro" "" { target c++26 } }
+#define char16_t 1 // { dg-error "keyword 'char16_t'
defined as macro" "" { target c++26 } }
+#define char32_t 1 // { dg-error "keyword 'char32_t'
defined as macro" "" { target c++26 } }
+#define char8_t 1 // { dg-error "keyword 'char8_t'
defined as macro" "" { target c++26 } }
+#define class 1 // { dg-error "keyword 'class'
defined as macro" "" { target c++26 } }
+#define co_await 1 // { dg-error "keyword 'co_await'
defined as macro" "" { target c++26 } }
+#define concept 1 // { dg-error "keyword 'concept'
defined as macro" "" { target c++26 } }
+#define const 1 // { dg-error "keyword 'const'
defined as macro" "" { target c++26 } }
+#define const_cast 1 // { dg-error "keyword 'const_cast'
defined as macro" "" { target c++26 } }
+#define consteval 1 // { dg-error "keyword 'consteval'
defined as macro" "" { target c++26 } }
+#define constexpr 1 // { dg-error "keyword 'constexpr'
defined as macro" "" { target c++26 } }
+#define constinit 1 // { dg-error "keyword 'constinit'
defined as macro" "" { target c++26 } }
+#define continue 1 // { dg-error "keyword 'continue'
defined as macro" "" { target c++26 } }
+#define contract_assert 1
+#define co_return 1 // { dg-error "keyword 'co_return'
defined as macro" "" { target c++26 } }
+#define co_yield 1 // { dg-error "keyword 'co_yield'
defined as macro" "" { target c++26 } }
+#define decltype 1 // { dg-error "keyword 'decltype'
defined as macro" "" { target c++26 } }
+#define default 1 // { dg-error "keyword 'default'
defined as macro" "" { target c++26 } }
+#define delete 1 // { dg-error "keyword 'delete' defined
as macro" "" { target c++26 } }
+#define do 1 // { dg-error "keyword 'do' defined as
macro" "" { target c++26 } }
+#define double 1 // { dg-error "keyword 'double' defined
as macro" "" { target c++26 } }
+#define dynamic_cast 1 // { dg-error "keyword 'dynamic_cast'
defined as macro" "" { target c++26 } }
+#define else 1 // { dg-error "keyword 'else' defined
as macro" "" { target c++26 } }
+#define enum 1 // { dg-error "keyword 'enum' defined
as macro" "" { target c++26 } }
+#define explicit 1 // { dg-error "keyword 'explicit'
defined as macro" "" { target c++26 } }
+#define export 1 // { dg-error "keyword 'export' defined
as macro" "" { target c++26 } }
+#define extern 1 // { dg-error "keyword 'extern' defined
as macro" "" { target c++26 } }
+#define false 1 // { dg-error "keyword 'false'
defined as macro" "" { target c++26 } }
+#define float 1 // { dg-error "keyword 'float'
defined as macro" "" { target c++26 } }
+#define for 1 // { dg-error "keyword 'for' defined as
macro" "" { target c++26 } }
+#define friend 1 // { dg-error "keyword 'friend' defined
as macro" "" { target c++26 } }
+#define goto 1 // { dg-error "keyword 'goto' defined
as macro" "" { target c++26 } }
+#define if 1 // { dg-error "keyword 'if' defined as
macro" "" { target c++26 } }
+#define inline 1 // { dg-error "keyword 'inline' defined
as macro" "" { target c++26 } }
+#define int 1 // { dg-error "keyword 'int' defined as
macro" "" { target c++26 } }
+#define long 1 // { dg-error "keyword 'long' defined
as macro" "" { target c++26 } }
+#define mutable 1 // { dg-error "keyword 'mutable'
defined as macro" "" { target c++26 } }
+#define namespace 1 // { dg-error "keyword 'namespace'
defined as macro" "" { target c++26 } }
+#define new 1 // { dg-error "keyword 'new' defined as
macro" "" { target c++26 } }
+#define noexcept 1 // { dg-error "keyword 'noexcept'
defined as macro" "" { target c++26 } }
+#define nullptr 1 // { dg-error "keyword 'nullptr'
defined as macro" "" { target c++26 } }
+#define operator 1 // { dg-error "keyword 'operator'
defined as macro" "" { target c++26 } }
+#define private 1 // { dg-error "keyword 'private'
defined as macro" "" { target c++26 } }
+#define protected 1 // { dg-error "keyword 'protected'
defined as macro" "" { target c++26 } }
+#define public 1 // { dg-error "keyword 'public' defined
as macro" "" { target c++26 } }
+#define register 1 // { dg-error "keyword 'register'
defined as macro" "" { target c++26 } }
+#define reinterpret_cast 1 // { dg-error "keyword
'reinterpret_cast' defined as macro" "" { target c++26 } }
+#define requires 1 // { dg-error "keyword 'requires'
defined as macro" "" { target c++26 } }
+#define return 1 // { dg-error "keyword 'return' defined
as macro" "" { target c++26 } }
+#define short 1 // { dg-error "keyword 'short'
defined as macro" "" { target c++26 } }
+#define signed 1 // { dg-error "keyword 'signed' defined
as macro" "" { target c++26 } }
+#define sizeof 1 // { dg-error "keyword 'sizeof' defined
as macro" "" { target c++26 } }
+#define static 1 // { dg-error "keyword 'static' defined
as macro" "" { target c++26 } }
+#define static_assert 1 // { dg-error "keyword
'static_assert' defined as macro" "" { target c++26 } }
+#define static_cast 1 // { dg-error "keyword 'static_cast'
defined as macro" "" { target c++26 } }
+#define struct 1 // { dg-error "keyword 'struct' defined
as macro" "" { target c++26 } }
+#define switch 1 // { dg-error "keyword 'switch' defined
as macro" "" { target c++26 } }
+#define template 1 // { dg-error "keyword 'template'
defined as macro" "" { target c++26 } }
+#define this 1 // { dg-error "keyword 'this' defined
as macro" "" { target c++26 } }
+#define thread_local 1 // { dg-error "keyword 'thread_local'
defined as macro" "" { target c++26 } }
+#define throw 1 // { dg-error "keyword 'throw'
defined as macro" "" { target c++26 } }
+#define true 1 // { dg-error "keyword 'true' defined
as macro" "" { target c++26 } }
+#define try 1 // { dg-error "keyword 'try' defined as
macro" "" { target c++26 } }
+#define typedef 1 // { dg-error "keyword 'typedef'
defined as macro" "" { target c++26 } }
+#define typeid 1 // { dg-error "keyword 'typeid' defined
as macro" "" { target c++26 } }
+#define typename 1 // { dg-error "keyword 'typename'
defined as macro" "" { target c++26 } }
+#define union 1 // { dg-error "keyword 'union'
defined as macro" "" { target c++26 } }
+#define unsigned 1 // { dg-error "keyword 'unsigned'
defined as macro" "" { target c++26 } }
+#define using 1 // { dg-error "keyword 'using'
defined as macro" "" { target c++26 } }
+#define virtual 1 // { dg-error "keyword 'virtual'
defined as macro" "" { target c++26 } }
+#define void 1 // { dg-error "keyword 'void' defined
as macro" "" { target c++26 } }
+#define volatile 1 // { dg-error "keyword 'volatile'
defined as macro" "" { target c++26 } }
+#define wchar_t 1 // { dg-error "keyword 'wchar_t'
defined as macro" "" { target c++26 } }
+#define while 1 // { dg-error "keyword 'while'
defined as macro" "" { target c++26 } }
+
+// [lex.name]
+#define final 1 // { dg-error "keyword 'final'
defined as macro" "" { target c++26 } }
+#define import 1 // { dg-error "keyword 'import' defined
as macro" "" { target c++26 } }
+#define module 1 // { dg-error "keyword 'module' defined
as macro" "" { target c++26 } }
+#define override 1 // { dg-error "keyword 'override'
defined as macro" "" { target c++26 } }
+#define post 1
+#define pre 1
+#define replaceable_if_eligible 1 // { dg-error "keyword
'replaceable_if_eligible' defined as macro" "" { target c++26 } }
+#define trivially_relocatable_if_eligible 1 // { dg-error "keyword
'trivially_relocatable_if_eligible' defined as macro" "" { target c++26 } }
+
+// [dcl.attr]
+#define assume 1 // { dg-error "keyword 'assume' defined
as macro" "" { target c++26 } }
+#define carries_dependency 1
+#define deprecated 1 // { dg-error "keyword 'deprecated'
defined as macro" "" { target c++26 } }
+#define fallthrough 1 // { dg-error "keyword 'fallthrough'
defined as macro" "" { target c++26 } }
+#define indeterminate 1
+#define likely 1 // { dg-error "keyword 'likely' defined
as macro" "" { target c++26 } }
+#define maybe_unused 1 // { dg-error "keyword 'maybe_unused'
defined as macro" "" { target c++26 } }
+#define nodiscard 1 // { dg-error "keyword 'nodiscard'
defined as macro" "" { target c++26 } }
+#define noreturn 1 // { dg-error "keyword 'noreturn'
defined as macro" "" { target c++26 } }
+#define no_unique_address 1 // { dg-error "keyword
'no_unique_address' defined as macro" "" { target c++26 } }
+#define unlikely 1 // { dg-error "keyword 'unlikely'
defined as macro" "" { target c++26 } }
--- gcc/testsuite/g++.dg/warn/Wkeyword-macro-2.C.jj 2025-07-31
14:33:35.670334012 +0200
+++ gcc/testsuite/g++.dg/warn/Wkeyword-macro-2.C 2025-07-31
17:24:23.820218747 +0200
@@ -0,0 +1,112 @@
+// C++26 P2843R3 - Preprocessing is never undefined
+// [cpp.replace.general]/9
+// { dg-do preprocess }
+// { dg-options "-pedantic" }
+// { dg-additional-options "-fmodules" { target c++20 } }
+
+// [lex.key]
+#define alignas 1 // { dg-warning "keyword 'alignas'
defined as macro" "" { target c++26 } }
+#define alignof 1 // { dg-warning "keyword 'alignof'
defined as macro" "" { target c++26 } }
+#define asm 1 // { dg-warning "keyword 'asm' defined
as macro" "" { target c++26 } }
+#define auto 1 // { dg-warning "keyword 'auto' defined
as macro" "" { target c++26 } }
+#define bool 1 // { dg-warning "keyword 'bool' defined
as macro" "" { target c++26 } }
+#define break 1 // { dg-warning "keyword
'break' defined as macro" "" { target c++26 } }
+#define case 1 // { dg-warning "keyword 'case' defined
as macro" "" { target c++26 } }
+#define catch 1 // { dg-warning "keyword
'catch' defined as macro" "" { target c++26 } }
+#define char 1 // { dg-warning "keyword 'char' defined
as macro" "" { target c++26 } }
+#define char16_t 1 // { dg-warning "keyword 'char16_t'
defined as macro" "" { target c++26 } }
+#define char32_t 1 // { dg-warning "keyword 'char32_t'
defined as macro" "" { target c++26 } }
+#define char8_t 1 // { dg-warning "keyword 'char8_t'
defined as macro" "" { target c++26 } }
+#define class 1 // { dg-warning "keyword
'class' defined as macro" "" { target c++26 } }
+#define co_await 1 // { dg-warning "keyword 'co_await'
defined as macro" "" { target c++26 } }
+#define concept 1 // { dg-warning "keyword 'concept'
defined as macro" "" { target c++26 } }
+#define const 1 // { dg-warning "keyword
'const' defined as macro" "" { target c++26 } }
+#define const_cast 1 // { dg-warning "keyword 'const_cast'
defined as macro" "" { target c++26 } }
+#define consteval 1 // { dg-warning "keyword 'consteval'
defined as macro" "" { target c++26 } }
+#define constexpr 1 // { dg-warning "keyword 'constexpr'
defined as macro" "" { target c++26 } }
+#define constinit 1 // { dg-warning "keyword 'constinit'
defined as macro" "" { target c++26 } }
+#define continue 1 // { dg-warning "keyword 'continue'
defined as macro" "" { target c++26 } }
+#define contract_assert 1
+#define co_return 1 // { dg-warning "keyword 'co_return'
defined as macro" "" { target c++26 } }
+#define co_yield 1 // { dg-warning "keyword 'co_yield'
defined as macro" "" { target c++26 } }
+#define decltype 1 // { dg-warning "keyword 'decltype'
defined as macro" "" { target c++26 } }
+#define default 1 // { dg-warning "keyword 'default'
defined as macro" "" { target c++26 } }
+#define delete 1 // { dg-warning "keyword 'delete'
defined as macro" "" { target c++26 } }
+#define do 1 // { dg-warning "keyword 'do' defined
as macro" "" { target c++26 } }
+#define double 1 // { dg-warning "keyword 'double'
defined as macro" "" { target c++26 } }
+#define dynamic_cast 1 // { dg-warning "keyword 'dynamic_cast'
defined as macro" "" { target c++26 } }
+#define else 1 // { dg-warning "keyword 'else' defined
as macro" "" { target c++26 } }
+#define enum 1 // { dg-warning "keyword 'enum' defined
as macro" "" { target c++26 } }
+#define explicit 1 // { dg-warning "keyword 'explicit'
defined as macro" "" { target c++26 } }
+#define export 1 // { dg-warning "keyword 'export'
defined as macro" "" { target c++26 } }
+#define extern 1 // { dg-warning "keyword 'extern'
defined as macro" "" { target c++26 } }
+#define false 1 // { dg-warning "keyword
'false' defined as macro" "" { target c++26 } }
+#define float 1 // { dg-warning "keyword
'float' defined as macro" "" { target c++26 } }
+#define for 1 // { dg-warning "keyword 'for' defined
as macro" "" { target c++26 } }
+#define friend 1 // { dg-warning "keyword 'friend'
defined as macro" "" { target c++26 } }
+#define goto 1 // { dg-warning "keyword 'goto' defined
as macro" "" { target c++26 } }
+#define if 1 // { dg-warning "keyword 'if' defined
as macro" "" { target c++26 } }
+#define inline 1 // { dg-warning "keyword 'inline'
defined as macro" "" { target c++26 } }
+#define int 1 // { dg-warning "keyword 'int' defined
as macro" "" { target c++26 } }
+#define long 1 // { dg-warning "keyword 'long' defined
as macro" "" { target c++26 } }
+#define mutable 1 // { dg-warning "keyword 'mutable'
defined as macro" "" { target c++26 } }
+#define namespace 1 // { dg-warning "keyword 'namespace'
defined as macro" "" { target c++26 } }
+#define new 1 // { dg-warning "keyword 'new' defined
as macro" "" { target c++26 } }
+#define noexcept 1 // { dg-warning "keyword 'noexcept'
defined as macro" "" { target c++26 } }
+#define nullptr 1 // { dg-warning "keyword 'nullptr'
defined as macro" "" { target c++26 } }
+#define operator 1 // { dg-warning "keyword 'operator'
defined as macro" "" { target c++26 } }
+#define private 1 // { dg-warning "keyword 'private'
defined as macro" "" { target c++26 } }
+#define protected 1 // { dg-warning "keyword 'protected'
defined as macro" "" { target c++26 } }
+#define public 1 // { dg-warning "keyword 'public'
defined as macro" "" { target c++26 } }
+#define register 1 // { dg-warning "keyword 'register'
defined as macro" "" { target c++26 } }
+#define reinterpret_cast 1 // { dg-warning "keyword
'reinterpret_cast' defined as macro" "" { target c++26 } }
+#define requires 1 // { dg-warning "keyword 'requires'
defined as macro" "" { target c++26 } }
+#define return 1 // { dg-warning "keyword 'return'
defined as macro" "" { target c++26 } }
+#define short 1 // { dg-warning "keyword
'short' defined as macro" "" { target c++26 } }
+#define signed 1 // { dg-warning "keyword 'signed'
defined as macro" "" { target c++26 } }
+#define sizeof 1 // { dg-warning "keyword 'sizeof'
defined as macro" "" { target c++26 } }
+#define static 1 // { dg-warning "keyword 'static'
defined as macro" "" { target c++26 } }
+#define static_assert 1 // { dg-warning "keyword
'static_assert' defined as macro" "" { target c++26 } }
+#define static_cast 1 // { dg-warning "keyword 'static_cast'
defined as macro" "" { target c++26 } }
+#define struct 1 // { dg-warning "keyword 'struct'
defined as macro" "" { target c++26 } }
+#define switch 1 // { dg-warning "keyword 'switch'
defined as macro" "" { target c++26 } }
+#define template 1 // { dg-warning "keyword 'template'
defined as macro" "" { target c++26 } }
+#define this 1 // { dg-warning "keyword 'this' defined
as macro" "" { target c++26 } }
+#define thread_local 1 // { dg-warning "keyword 'thread_local'
defined as macro" "" { target c++26 } }
+#define throw 1 // { dg-warning "keyword
'throw' defined as macro" "" { target c++26 } }
+#define true 1 // { dg-warning "keyword 'true' defined
as macro" "" { target c++26 } }
+#define try 1 // { dg-warning "keyword 'try' defined
as macro" "" { target c++26 } }
+#define typedef 1 // { dg-warning "keyword 'typedef'
defined as macro" "" { target c++26 } }
+#define typeid 1 // { dg-warning "keyword 'typeid'
defined as macro" "" { target c++26 } }
+#define typename 1 // { dg-warning "keyword 'typename'
defined as macro" "" { target c++26 } }
+#define union 1 // { dg-warning "keyword
'union' defined as macro" "" { target c++26 } }
+#define unsigned 1 // { dg-warning "keyword 'unsigned'
defined as macro" "" { target c++26 } }
+#define using 1 // { dg-warning "keyword
'using' defined as macro" "" { target c++26 } }
+#define virtual 1 // { dg-warning "keyword 'virtual'
defined as macro" "" { target c++26 } }
+#define void 1 // { dg-warning "keyword 'void' defined
as macro" "" { target c++26 } }
+#define volatile 1 // { dg-warning "keyword 'volatile'
defined as macro" "" { target c++26 } }
+#define wchar_t 1 // { dg-warning "keyword 'wchar_t'
defined as macro" "" { target c++26 } }
+#define while 1 // { dg-warning "keyword
'while' defined as macro" "" { target c++26 } }
+
+// [lex.name]
+#define final 1 // { dg-warning "keyword
'final' defined as macro" "" { target c++26 } }
+#define import 1 // { dg-warning "keyword 'import'
defined as macro" "" { target c++26 } }
+#define module 1 // { dg-warning "keyword 'module'
defined as macro" "" { target c++26 } }
+#define override 1 // { dg-warning "keyword 'override'
defined as macro" "" { target c++26 } }
+#define post 1
+#define pre 1
+#define replaceable_if_eligible 1 // { dg-warning "keyword
'replaceable_if_eligible' defined as macro" "" { target c++26 } }
+#define trivially_relocatable_if_eligible 1 // { dg-warning "keyword
'trivially_relocatable_if_eligible' defined as macro" "" { target c++26 } }
+
+// [dcl.attr]
+#define assume 1 // { dg-warning "keyword 'assume'
defined as macro" "" { target c++26 } }
+#define carries_dependency 1
+#define deprecated 1 // { dg-warning "keyword 'deprecated'
defined as macro" "" { target c++26 } }
+#define fallthrough 1 // { dg-warning "keyword 'fallthrough'
defined as macro" "" { target c++26 } }
+#define indeterminate 1
+#define likely 1 // { dg-warning "keyword 'likely'
defined as macro" "" { target c++26 } }
+#define maybe_unused 1 // { dg-warning "keyword 'maybe_unused'
defined as macro" "" { target c++26 } }
+#define nodiscard 1 // { dg-warning "keyword 'nodiscard'
defined as macro" "" { target c++26 } }
+#define noreturn 1 // { dg-warning "keyword 'noreturn'
defined as macro" "" { target c++26 } }
+#define no_unique_address 1 // { dg-warning "keyword
'no_unique_address' defined as macro" "" { target c++26 } }
+#define unlikely 1 // { dg-warning "keyword 'unlikely'
defined as macro" "" { target c++26 } }
--- gcc/testsuite/g++.dg/warn/Wkeyword-macro-3.C.jj 2025-07-31
14:34:16.956792719 +0200
+++ gcc/testsuite/g++.dg/warn/Wkeyword-macro-3.C 2025-07-31
14:34:34.904557416 +0200
@@ -0,0 +1,7 @@
+// C++26 P2843R3 - Preprocessing is never undefined
+// [cpp.replace.general]/9
+// { dg-do preprocess }
+// { dg-options "" }
+// { dg-additional-options "-fmodules" { target c++20 } }
+
+#include "Wkeyword-macro-1.C"
--- gcc/testsuite/g++.dg/warn/Wkeyword-macro-4.C.jj 2025-07-31
14:41:36.592031205 +0200
+++ gcc/testsuite/g++.dg/warn/Wkeyword-macro-4.C 2025-07-31
17:24:35.599062600 +0200
@@ -0,0 +1,112 @@
+// C++26 P2843R3 - Preprocessing is never undefined
+// [cpp.replace.general]/9
+// { dg-do preprocess }
+// { dg-options "-pedantic-errors" }
+// { dg-additional-options "-fmodules" { target c++20 } }
+
+// [lex.key]
+#undef alignas // { dg-error "undefining
keyword 'alignas'" "" { target c++26 } }
+#undef alignof // { dg-error "undefining
keyword 'alignof'" "" { target c++26 } }
+#undef asm // { dg-error "undefining keyword
'asm'" "" { target c++26 } }
+#undef auto // { dg-error "undefining keyword
'auto'" "" { target c++26 } }
+#undef bool // { dg-error "undefining keyword
'bool'" "" { target c++26 } }
+#undef break // { dg-error "undefining keyword
'break'" "" { target c++26 } }
+#undef case // { dg-error "undefining keyword
'case'" "" { target c++26 } }
+#undef catch // { dg-error "undefining keyword
'catch'" "" { target c++26 } }
+#undef char // { dg-error "undefining keyword
'char'" "" { target c++26 } }
+#undef char16_t // { dg-error "undefining keyword
'char16_t'" "" { target c++26 } }
+#undef char32_t // { dg-error "undefining keyword
'char32_t'" "" { target c++26 } }
+#undef char8_t // { dg-error "undefining
keyword 'char8_t'" "" { target c++26 } }
+#undef class // { dg-error "undefining keyword
'class'" "" { target c++26 } }
+#undef co_await // { dg-error "undefining keyword
'co_await'" "" { target c++26 } }
+#undef concept // { dg-error "undefining
keyword 'concept'" "" { target c++26 } }
+#undef const // { dg-error "undefining keyword
'const'" "" { target c++26 } }
+#undef const_cast // { dg-error "undefining keyword
'const_cast'" "" { target c++26 } }
+#undef consteval // { dg-error "undefining keyword
'consteval'" "" { target c++26 } }
+#undef constexpr // { dg-error "undefining keyword
'constexpr'" "" { target c++26 } }
+#undef constinit // { dg-error "undefining keyword
'constinit'" "" { target c++26 } }
+#undef continue // { dg-error "undefining keyword
'continue'" "" { target c++26 } }
+#undef contract_assert
+#undef co_return // { dg-error "undefining keyword
'co_return'" "" { target c++26 } }
+#undef co_yield // { dg-error "undefining keyword
'co_yield'" "" { target c++26 } }
+#undef decltype // { dg-error "undefining keyword
'decltype'" "" { target c++26 } }
+#undef default // { dg-error "undefining
keyword 'default'" "" { target c++26 } }
+#undef delete // { dg-error "undefining keyword
'delete'" "" { target c++26 } }
+#undef do // { dg-error "undefining keyword 'do'"
"" { target c++26 } }
+#undef double // { dg-error "undefining keyword
'double'" "" { target c++26 } }
+#undef dynamic_cast // { dg-error "undefining keyword
'dynamic_cast'" "" { target c++26 } }
+#undef else // { dg-error "undefining keyword
'else'" "" { target c++26 } }
+#undef enum // { dg-error "undefining keyword
'enum'" "" { target c++26 } }
+#undef explicit // { dg-error "undefining keyword
'explicit'" "" { target c++26 } }
+#undef export // { dg-error "undefining keyword
'export'" "" { target c++26 } }
+#undef extern // { dg-error "undefining keyword
'extern'" "" { target c++26 } }
+#undef false // { dg-error "undefining keyword
'false'" "" { target c++26 } }
+#undef float // { dg-error "undefining keyword
'float'" "" { target c++26 } }
+#undef for // { dg-error "undefining keyword
'for'" "" { target c++26 } }
+#undef friend // { dg-error "undefining keyword
'friend'" "" { target c++26 } }
+#undef goto // { dg-error "undefining keyword
'goto'" "" { target c++26 } }
+#undef if // { dg-error "undefining keyword 'if'"
"" { target c++26 } }
+#undef inline // { dg-error "undefining keyword
'inline'" "" { target c++26 } }
+#undef int // { dg-error "undefining keyword
'int'" "" { target c++26 } }
+#undef long // { dg-error "undefining keyword
'long'" "" { target c++26 } }
+#undef mutable // { dg-error "undefining
keyword 'mutable'" "" { target c++26 } }
+#undef namespace // { dg-error "undefining keyword
'namespace'" "" { target c++26 } }
+#undef new // { dg-error "undefining keyword
'new'" "" { target c++26 } }
+#undef noexcept // { dg-error "undefining keyword
'noexcept'" "" { target c++26 } }
+#undef nullptr // { dg-error "undefining
keyword 'nullptr'" "" { target c++26 } }
+#undef operator // { dg-error "undefining keyword
'operator'" "" { target c++26 } }
+#undef private // { dg-error "undefining
keyword 'private'" "" { target c++26 } }
+#undef protected // { dg-error "undefining keyword
'protected'" "" { target c++26 } }
+#undef public // { dg-error "undefining keyword
'public'" "" { target c++26 } }
+#undef register // { dg-error "undefining keyword
'register'" "" { target c++26 } }
+#undef reinterpret_cast // { dg-error "undefining keyword
'reinterpret_cast'" "" { target c++26 } }
+#undef requires // { dg-error "undefining keyword
'requires'" "" { target c++26 } }
+#undef return // { dg-error "undefining keyword
'return'" "" { target c++26 } }
+#undef short // { dg-error "undefining keyword
'short'" "" { target c++26 } }
+#undef signed // { dg-error "undefining keyword
'signed'" "" { target c++26 } }
+#undef sizeof // { dg-error "undefining keyword
'sizeof'" "" { target c++26 } }
+#undef static // { dg-error "undefining keyword
'static'" "" { target c++26 } }
+#undef static_assert // { dg-error "undefining keyword
'static_assert'" "" { target c++26 } }
+#undef static_cast // { dg-error "undefining keyword
'static_cast'" "" { target c++26 } }
+#undef struct // { dg-error "undefining keyword
'struct'" "" { target c++26 } }
+#undef switch // { dg-error "undefining keyword
'switch'" "" { target c++26 } }
+#undef template // { dg-error "undefining keyword
'template'" "" { target c++26 } }
+#undef this // { dg-error "undefining keyword
'this'" "" { target c++26 } }
+#undef thread_local // { dg-error "undefining keyword
'thread_local'" "" { target c++26 } }
+#undef throw // { dg-error "undefining keyword
'throw'" "" { target c++26 } }
+#undef true // { dg-error "undefining keyword
'true'" "" { target c++26 } }
+#undef try // { dg-error "undefining keyword
'try'" "" { target c++26 } }
+#undef typedef // { dg-error "undefining
keyword 'typedef'" "" { target c++26 } }
+#undef typeid // { dg-error "undefining keyword
'typeid'" "" { target c++26 } }
+#undef typename // { dg-error "undefining keyword
'typename'" "" { target c++26 } }
+#undef union // { dg-error "undefining keyword
'union'" "" { target c++26 } }
+#undef unsigned // { dg-error "undefining keyword
'unsigned'" "" { target c++26 } }
+#undef using // { dg-error "undefining keyword
'using'" "" { target c++26 } }
+#undef virtual // { dg-error "undefining
keyword 'virtual'" "" { target c++26 } }
+#undef void // { dg-error "undefining keyword
'void'" "" { target c++26 } }
+#undef volatile // { dg-error "undefining keyword
'volatile'" "" { target c++26 } }
+#undef wchar_t // { dg-error "undefining
keyword 'wchar_t'" "" { target c++26 } }
+#undef while // { dg-error "undefining keyword
'while'" "" { target c++26 } }
+
+// [lex.name]
+#undef final // { dg-error "undefining keyword
'final'" "" { target c++26 } }
+#undef import // { dg-error "undefining keyword
'import'" "" { target c++26 } }
+#undef module // { dg-error "undefining keyword
'module'" "" { target c++26 } }
+#undef override // { dg-error "undefining keyword
'override'" "" { target c++26 } }
+#undef post
+#undef pre
+#undef replaceable_if_eligible // { dg-error "undefining keyword
'replaceable_if_eligible'" "" { target c++26 } }
+#undef trivially_relocatable_if_eligible // { dg-error "undefining
keyword 'trivially_relocatable_if_eligible'" "" { target c++26 } }
+
+// [dcl.attr]
+#undef assume // { dg-error "undefining keyword
'assume'" "" { target c++26 } }
+#undef carries_dependency
+#undef deprecated // { dg-error "undefining keyword
'deprecated'" "" { target c++26 } }
+#undef fallthrough // { dg-error "undefining keyword
'fallthrough'" "" { target c++26 } }
+#undef indeterminate
+#undef likely // { dg-error "undefining keyword
'likely'" "" { target c++26 } }
+#undef maybe_unused // { dg-error "undefining keyword
'maybe_unused'" "" { target c++26 } }
+#undef nodiscard // { dg-error "undefining keyword
'nodiscard'" "" { target c++26 } }
+#undef noreturn // { dg-error "undefining
keyword 'noreturn'" "" { target c++26 } }
+#undef no_unique_address // { dg-error "undefining keyword
'no_unique_address'" "" { target c++26 } }
+#undef unlikely // { dg-error "undefining
keyword 'unlikely'" "" { target c++26 } }
--- gcc/testsuite/g++.dg/warn/Wkeyword-macro-5.C.jj 2025-07-31
14:47:10.012662132 +0200
+++ gcc/testsuite/g++.dg/warn/Wkeyword-macro-5.C 2025-07-31
17:24:45.244934733 +0200
@@ -0,0 +1,112 @@
+// C++26 P2843R3 - Preprocessing is never undefined
+// [cpp.replace.general]/9
+// { dg-do preprocess }
+// { dg-options "-pedantic" }
+// { dg-additional-options "-fmodules" { target c++20 } }
+
+// [lex.key]
+#undef alignas // { dg-warning "undefining
keyword 'alignas'" "" { target c++26 } }
+#undef alignof // { dg-warning "undefining
keyword 'alignof'" "" { target c++26 } }
+#undef asm // { dg-warning "undefining keyword
'asm'" "" { target c++26 } }
+#undef auto // { dg-warning "undefining keyword
'auto'" "" { target c++26 } }
+#undef bool // { dg-warning "undefining keyword
'bool'" "" { target c++26 } }
+#undef break // { dg-warning "undefining keyword
'break'" "" { target c++26 } }
+#undef case // { dg-warning "undefining keyword
'case'" "" { target c++26 } }
+#undef catch // { dg-warning "undefining keyword
'catch'" "" { target c++26 } }
+#undef char // { dg-warning "undefining keyword
'char'" "" { target c++26 } }
+#undef char16_t // { dg-warning "undefining keyword
'char16_t'" "" { target c++26 } }
+#undef char32_t // { dg-warning "undefining keyword
'char32_t'" "" { target c++26 } }
+#undef char8_t // { dg-warning "undefining
keyword 'char8_t'" "" { target c++26 } }
+#undef class // { dg-warning "undefining keyword
'class'" "" { target c++26 } }
+#undef co_await // { dg-warning "undefining keyword
'co_await'" "" { target c++26 } }
+#undef concept // { dg-warning "undefining
keyword 'concept'" "" { target c++26 } }
+#undef const // { dg-warning "undefining keyword
'const'" "" { target c++26 } }
+#undef const_cast // { dg-warning "undefining keyword
'const_cast'" "" { target c++26 } }
+#undef consteval // { dg-warning "undefining keyword
'consteval'" "" { target c++26 } }
+#undef constexpr // { dg-warning "undefining keyword
'constexpr'" "" { target c++26 } }
+#undef constinit // { dg-warning "undefining keyword
'constinit'" "" { target c++26 } }
+#undef continue // { dg-warning "undefining keyword
'continue'" "" { target c++26 } }
+#undef contract_assert
+#undef co_return // { dg-warning "undefining keyword
'co_return'" "" { target c++26 } }
+#undef co_yield // { dg-warning "undefining keyword
'co_yield'" "" { target c++26 } }
+#undef decltype // { dg-warning "undefining keyword
'decltype'" "" { target c++26 } }
+#undef default // { dg-warning "undefining
keyword 'default'" "" { target c++26 } }
+#undef delete // { dg-warning "undefining keyword
'delete'" "" { target c++26 } }
+#undef do // { dg-warning "undefining keyword
'do'" "" { target c++26 } }
+#undef double // { dg-warning "undefining keyword
'double'" "" { target c++26 } }
+#undef dynamic_cast // { dg-warning "undefining keyword
'dynamic_cast'" "" { target c++26 } }
+#undef else // { dg-warning "undefining keyword
'else'" "" { target c++26 } }
+#undef enum // { dg-warning "undefining keyword
'enum'" "" { target c++26 } }
+#undef explicit // { dg-warning "undefining keyword
'explicit'" "" { target c++26 } }
+#undef export // { dg-warning "undefining keyword
'export'" "" { target c++26 } }
+#undef extern // { dg-warning "undefining keyword
'extern'" "" { target c++26 } }
+#undef false // { dg-warning "undefining keyword
'false'" "" { target c++26 } }
+#undef float // { dg-warning "undefining keyword
'float'" "" { target c++26 } }
+#undef for // { dg-warning "undefining keyword
'for'" "" { target c++26 } }
+#undef friend // { dg-warning "undefining keyword
'friend'" "" { target c++26 } }
+#undef goto // { dg-warning "undefining keyword
'goto'" "" { target c++26 } }
+#undef if // { dg-warning "undefining keyword
'if'" "" { target c++26 } }
+#undef inline // { dg-warning "undefining keyword
'inline'" "" { target c++26 } }
+#undef int // { dg-warning "undefining keyword
'int'" "" { target c++26 } }
+#undef long // { dg-warning "undefining keyword
'long'" "" { target c++26 } }
+#undef mutable // { dg-warning "undefining
keyword 'mutable'" "" { target c++26 } }
+#undef namespace // { dg-warning "undefining keyword
'namespace'" "" { target c++26 } }
+#undef new // { dg-warning "undefining keyword
'new'" "" { target c++26 } }
+#undef noexcept // { dg-warning "undefining keyword
'noexcept'" "" { target c++26 } }
+#undef nullptr // { dg-warning "undefining
keyword 'nullptr'" "" { target c++26 } }
+#undef operator // { dg-warning "undefining keyword
'operator'" "" { target c++26 } }
+#undef private // { dg-warning "undefining
keyword 'private'" "" { target c++26 } }
+#undef protected // { dg-warning "undefining keyword
'protected'" "" { target c++26 } }
+#undef public // { dg-warning "undefining keyword
'public'" "" { target c++26 } }
+#undef register // { dg-warning "undefining keyword
'register'" "" { target c++26 } }
+#undef reinterpret_cast // { dg-warning "undefining keyword
'reinterpret_cast'" "" { target c++26 } }
+#undef requires // { dg-warning "undefining keyword
'requires'" "" { target c++26 } }
+#undef return // { dg-warning "undefining keyword
'return'" "" { target c++26 } }
+#undef short // { dg-warning "undefining keyword
'short'" "" { target c++26 } }
+#undef signed // { dg-warning "undefining keyword
'signed'" "" { target c++26 } }
+#undef sizeof // { dg-warning "undefining keyword
'sizeof'" "" { target c++26 } }
+#undef static // { dg-warning "undefining keyword
'static'" "" { target c++26 } }
+#undef static_assert // { dg-warning "undefining keyword
'static_assert'" "" { target c++26 } }
+#undef static_cast // { dg-warning "undefining keyword
'static_cast'" "" { target c++26 } }
+#undef struct // { dg-warning "undefining keyword
'struct'" "" { target c++26 } }
+#undef switch // { dg-warning "undefining keyword
'switch'" "" { target c++26 } }
+#undef template // { dg-warning "undefining keyword
'template'" "" { target c++26 } }
+#undef this // { dg-warning "undefining keyword
'this'" "" { target c++26 } }
+#undef thread_local // { dg-warning "undefining keyword
'thread_local'" "" { target c++26 } }
+#undef throw // { dg-warning "undefining keyword
'throw'" "" { target c++26 } }
+#undef true // { dg-warning "undefining keyword
'true'" "" { target c++26 } }
+#undef try // { dg-warning "undefining keyword
'try'" "" { target c++26 } }
+#undef typedef // { dg-warning "undefining
keyword 'typedef'" "" { target c++26 } }
+#undef typeid // { dg-warning "undefining keyword
'typeid'" "" { target c++26 } }
+#undef typename // { dg-warning "undefining keyword
'typename'" "" { target c++26 } }
+#undef union // { dg-warning "undefining keyword
'union'" "" { target c++26 } }
+#undef unsigned // { dg-warning "undefining keyword
'unsigned'" "" { target c++26 } }
+#undef using // { dg-warning "undefining keyword
'using'" "" { target c++26 } }
+#undef virtual // { dg-warning "undefining
keyword 'virtual'" "" { target c++26 } }
+#undef void // { dg-warning "undefining keyword
'void'" "" { target c++26 } }
+#undef volatile // { dg-warning "undefining keyword
'volatile'" "" { target c++26 } }
+#undef wchar_t // { dg-warning "undefining
keyword 'wchar_t'" "" { target c++26 } }
+#undef while // { dg-warning "undefining keyword
'while'" "" { target c++26 } }
+
+// [lex.name]
+#undef final // { dg-warning "undefining keyword
'final'" "" { target c++26 } }
+#undef import // { dg-warning "undefining keyword
'import'" "" { target c++26 } }
+#undef module // { dg-warning "undefining keyword
'module'" "" { target c++26 } }
+#undef override // { dg-warning "undefining keyword
'override'" "" { target c++26 } }
+#undef post
+#undef pre
+#undef replaceable_if_eligible // { dg-warning "undefining keyword
'replaceable_if_eligible'" "" { target c++26 } }
+#undef trivially_relocatable_if_eligible // { dg-warning "undefining
keyword 'trivially_relocatable_if_eligible'" "" { target c++26 } }
+
+// [dcl.attr]
+#undef assume // { dg-warning "undefining keyword
'assume'" "" { target c++26 } }
+#undef carries_dependency
+#undef deprecated // { dg-warning "undefining keyword
'deprecated'" "" { target c++26 } }
+#undef fallthrough // { dg-warning "undefining keyword
'fallthrough'" "" { target c++26 } }
+#undef indeterminate
+#undef likely // { dg-warning "undefining keyword
'likely'" "" { target c++26 } }
+#undef maybe_unused // { dg-warning "undefining keyword
'maybe_unused'" "" { target c++26 } }
+#undef nodiscard // { dg-warning "undefining keyword
'nodiscard'" "" { target c++26 } }
+#undef noreturn // { dg-warning "undefining
keyword 'noreturn'" "" { target c++26 } }
+#undef no_unique_address // { dg-warning "undefining keyword
'no_unique_address'" "" { target c++26 } }
+#undef unlikely // { dg-warning "undefining
keyword 'unlikely'" "" { target c++26 } }
--- gcc/testsuite/g++.dg/warn/Wkeyword-macro-6.C.jj 2025-07-31
14:47:42.294239120 +0200
+++ gcc/testsuite/g++.dg/warn/Wkeyword-macro-6.C 2025-07-31
14:48:03.381962790 +0200
@@ -0,0 +1,7 @@
+// C++26 P2843R3 - Preprocessing is never undefined
+// [cpp.replace.general]/9
+// { dg-do preprocess }
+// { dg-options "" }
+// { dg-additional-options "-fmodules" { target c++20 } }
+
+#include "Wkeyword-macro-4.C"
--- gcc/testsuite/g++.dg/warn/Wkeyword-macro-7.C.jj 2025-07-31
14:50:49.554785299 +0200
+++ gcc/testsuite/g++.dg/warn/Wkeyword-macro-7.C 2025-07-31
17:25:24.001420949 +0200
@@ -0,0 +1,112 @@
+// C++26 P2843R3 - Preprocessing is never undefined
+// [cpp.replace.general]/9
+// { dg-do preprocess }
+// { dg-options "-Wkeyword-macro" }
+// { dg-additional-options "-fmodules" { target c++20 } }
+
+// [lex.key]
+#define alignas 1 // { dg-warning "keyword 'alignas'
defined as macro" "" { target c++11 } }
+#define alignof 1 // { dg-warning "keyword 'alignof'
defined as macro" "" { target c++11 } }
+#define asm 1 // { dg-warning "keyword 'asm' defined
as macro" }
+#define auto 1 // { dg-warning "keyword 'auto' defined
as macro" }
+#define bool 1 // { dg-warning "keyword 'bool' defined
as macro" }
+#define break 1 // { dg-warning "keyword
'break' defined as macro" }
+#define case 1 // { dg-warning "keyword 'case' defined
as macro" }
+#define catch 1 // { dg-warning "keyword
'catch' defined as macro" }
+#define char 1 // { dg-warning "keyword 'char' defined
as macro" }
+#define char16_t 1 // { dg-warning "keyword 'char16_t'
defined as macro" "" { target c++11 } }
+#define char32_t 1 // { dg-warning "keyword 'char32_t'
defined as macro" "" { target c++11 } }
+#define char8_t 1 // { dg-warning "keyword 'char8_t'
defined as macro" "" { target c++20 } }
+#define class 1 // { dg-warning "keyword
'class' defined as macro" }
+#define co_await 1 // { dg-warning "keyword 'co_await'
defined as macro" "" { target c++20 } }
+#define concept 1 // { dg-warning "keyword 'concept'
defined as macro" "" { target c++20 } }
+#define const 1 // { dg-warning "keyword
'const' defined as macro" }
+#define const_cast 1 // { dg-warning "keyword 'const_cast'
defined as macro" }
+#define consteval 1 // { dg-warning "keyword 'consteval'
defined as macro" "" { target c++20 } }
+#define constexpr 1 // { dg-warning "keyword 'constexpr'
defined as macro" "" { target c++11 } }
+#define constinit 1 // { dg-warning "keyword 'constinit'
defined as macro" "" { target c++20 } }
+#define continue 1 // { dg-warning "keyword 'continue'
defined as macro" }
+#define contract_assert 1
+#define co_return 1 // { dg-warning "keyword 'co_return'
defined as macro" "" { target c++20 } }
+#define co_yield 1 // { dg-warning "keyword 'co_yield'
defined as macro" "" { target c++20 } }
+#define decltype 1 // { dg-warning "keyword 'decltype'
defined as macro" "" { target c++11 } }
+#define default 1 // { dg-warning "keyword 'default'
defined as macro" }
+#define delete 1 // { dg-warning "keyword 'delete'
defined as macro" }
+#define do 1 // { dg-warning "keyword 'do' defined
as macro" }
+#define double 1 // { dg-warning "keyword 'double'
defined as macro" }
+#define dynamic_cast 1 // { dg-warning "keyword 'dynamic_cast'
defined as macro" }
+#define else 1 // { dg-warning "keyword 'else' defined
as macro" }
+#define enum 1 // { dg-warning "keyword 'enum' defined
as macro" }
+#define explicit 1 // { dg-warning "keyword 'explicit'
defined as macro" }
+#define export 1 // { dg-warning "keyword 'export'
defined as macro" }
+#define extern 1 // { dg-warning "keyword 'extern'
defined as macro" }
+#define false 1 // { dg-warning "keyword
'false' defined as macro" }
+#define float 1 // { dg-warning "keyword
'float' defined as macro" }
+#define for 1 // { dg-warning "keyword 'for' defined
as macro" }
+#define friend 1 // { dg-warning "keyword 'friend'
defined as macro" }
+#define goto 1 // { dg-warning "keyword 'goto' defined
as macro" }
+#define if 1 // { dg-warning "keyword 'if' defined
as macro" }
+#define inline 1 // { dg-warning "keyword 'inline'
defined as macro" }
+#define int 1 // { dg-warning "keyword 'int' defined
as macro" }
+#define long 1 // { dg-warning "keyword 'long' defined
as macro" }
+#define mutable 1 // { dg-warning "keyword 'mutable'
defined as macro" }
+#define namespace 1 // { dg-warning "keyword 'namespace'
defined as macro" }
+#define new 1 // { dg-warning "keyword 'new' defined
as macro" }
+#define noexcept 1 // { dg-warning "keyword 'noexcept'
defined as macro" "" { target c++11 } }
+#define nullptr 1 // { dg-warning "keyword 'nullptr'
defined as macro" "" { target c++11 } }
+#define operator 1 // { dg-warning "keyword 'operator'
defined as macro" }
+#define private 1 // { dg-warning "keyword 'private'
defined as macro" }
+#define protected 1 // { dg-warning "keyword 'protected'
defined as macro" }
+#define public 1 // { dg-warning "keyword 'public'
defined as macro" }
+#define register 1 // { dg-warning "keyword 'register'
defined as macro" }
+#define reinterpret_cast 1 // { dg-warning "keyword
'reinterpret_cast' defined as macro" }
+#define requires 1 // { dg-warning "keyword 'requires'
defined as macro" "" { target c++20 } }
+#define return 1 // { dg-warning "keyword 'return'
defined as macro" }
+#define short 1 // { dg-warning "keyword
'short' defined as macro" }
+#define signed 1 // { dg-warning "keyword 'signed'
defined as macro" }
+#define sizeof 1 // { dg-warning "keyword 'sizeof'
defined as macro" }
+#define static 1 // { dg-warning "keyword 'static'
defined as macro" }
+#define static_assert 1 // { dg-warning "keyword
'static_assert' defined as macro" "" { target c++11 } }
+#define static_cast 1 // { dg-warning "keyword 'static_cast'
defined as macro" }
+#define struct 1 // { dg-warning "keyword 'struct'
defined as macro" }
+#define switch 1 // { dg-warning "keyword 'switch'
defined as macro" }
+#define template 1 // { dg-warning "keyword 'template'
defined as macro" }
+#define this 1 // { dg-warning "keyword 'this' defined
as macro" }
+#define thread_local 1 // { dg-warning "keyword 'thread_local'
defined as macro" "" { target c++11 } }
+#define throw 1 // { dg-warning "keyword
'throw' defined as macro" }
+#define true 1 // { dg-warning "keyword 'true' defined
as macro" }
+#define try 1 // { dg-warning "keyword 'try' defined
as macro" }
+#define typedef 1 // { dg-warning "keyword 'typedef'
defined as macro" }
+#define typeid 1 // { dg-warning "keyword 'typeid'
defined as macro" }
+#define typename 1 // { dg-warning "keyword 'typename'
defined as macro" }
+#define union 1 // { dg-warning "keyword
'union' defined as macro" }
+#define unsigned 1 // { dg-warning "keyword 'unsigned'
defined as macro" }
+#define using 1 // { dg-warning "keyword
'using' defined as macro" }
+#define virtual 1 // { dg-warning "keyword 'virtual'
defined as macro" }
+#define void 1 // { dg-warning "keyword 'void' defined
as macro" }
+#define volatile 1 // { dg-warning "keyword 'volatile'
defined as macro" }
+#define wchar_t 1 // { dg-warning "keyword 'wchar_t'
defined as macro" }
+#define while 1 // { dg-warning "keyword
'while' defined as macro" }
+
+// [lex.name]
+#define final 1 // { dg-warning "keyword
'final' defined as macro" "" { target c++11 } }
+#define import 1 // { dg-warning "keyword 'import'
defined as macro" "" { target c++20 } }
+#define module 1 // { dg-warning "keyword 'module'
defined as macro" "" { target c++20 } }
+#define override 1 // { dg-warning "keyword 'override'
defined as macro" "" { target c++11 } }
+#define post 1
+#define pre 1
+#define replaceable_if_eligible 1 // { dg-warning "keyword
'replaceable_if_eligible' defined as macro" "" { target c++26 } }
+#define trivially_relocatable_if_eligible 1 // { dg-warning "keyword
'trivially_relocatable_if_eligible' defined as macro" "" { target c++26 } }
+
+// [dcl.attr]
+#define assume 1 // { dg-warning "keyword 'assume'
defined as macro" "" { target c++23 } }
+#define carries_dependency 1 // { dg-warning "keyword
'carries_dependency' defined as macro" "" { target { c++11 && c++23_down } } }
+#define deprecated 1 // { dg-warning "keyword 'deprecated'
defined as macro" "" { target c++14 } }
+#define fallthrough 1 // { dg-warning "keyword 'fallthrough'
defined as macro" "" { target c++17 } }
+#define indeterminate 1
+#define likely 1 // { dg-warning "keyword 'likely'
defined as macro" "" { target c++20 } }
+#define maybe_unused 1 // { dg-warning "keyword 'maybe_unused'
defined as macro" "" { target c++17 } }
+#define nodiscard 1 // { dg-warning "keyword 'nodiscard'
defined as macro" "" { target c++17 } }
+#define noreturn 1 // { dg-warning "keyword 'noreturn'
defined as macro" "" { target c++11 } }
+#define no_unique_address 1 // { dg-warning "keyword
'no_unique_address' defined as macro" "" { target c++20 } }
+#define unlikely 1 // { dg-warning "keyword 'unlikely'
defined as macro" "" { target c++20 } }
--- gcc/testsuite/g++.dg/warn/Wkeyword-macro-8.C.jj 2025-07-31
15:38:36.320161860 +0200
+++ gcc/testsuite/g++.dg/warn/Wkeyword-macro-8.C 2025-07-31
17:26:03.357899209 +0200
@@ -0,0 +1,112 @@
+// C++26 P2843R3 - Preprocessing is never undefined
+// [cpp.replace.general]/9
+// { dg-do preprocess }
+// { dg-options "-Wkeyword-macro" }
+// { dg-additional-options "-fmodules" { target c++20 } }
+
+// [lex.key]
+#undef alignas // { dg-warning "undefining keyword
'alignas'" "" { target c++11 } }
+#undef alignof // { dg-warning "undefining keyword
'alignof'" "" { target c++11 } }
+#undef asm // { dg-warning "undefining keyword
'asm'" }
+#undef auto // { dg-warning "undefining keyword
'auto'" }
+#undef bool // { dg-warning "undefining keyword
'bool'" }
+#undef break // { dg-warning "undefining keyword
'break'" }
+#undef case // { dg-warning "undefining keyword
'case'" }
+#undef catch // { dg-warning "undefining keyword
'catch'" }
+#undef char // { dg-warning "undefining keyword
'char'" }
+#undef char16_t // { dg-warning "undefining
keyword 'char16_t'" "" { target c++11 } }
+#undef char32_t // { dg-warning "undefining
keyword 'char32_t'" "" { target c++11 } }
+#undef char8_t // { dg-warning "undefining keyword
'char8_t'" "" { target c++20 } }
+#undef class // { dg-warning "undefining keyword
'class'" }
+#undef co_await // { dg-warning "undefining
keyword 'co_await'" "" { target c++20 } }
+#undef concept // { dg-warning "undefining keyword
'concept'" "" { target c++20 } }
+#undef const // { dg-warning "undefining keyword
'const'" }
+#undef const_cast // { dg-warning "undefining keyword
'const_cast'" }
+#undef consteval // { dg-warning "undefining keyword
'consteval'" "" { target c++20 } }
+#undef constexpr // { dg-warning "undefining keyword
'constexpr'" "" { target c++11 } }
+#undef constinit // { dg-warning "undefining keyword
'constinit'" "" { target c++20 } }
+#undef continue // { dg-warning "undefining
keyword 'continue'" }
+#undef contract_assert
+#undef co_return // { dg-warning "undefining keyword
'co_return'" "" { target c++20 } }
+#undef co_yield // { dg-warning "undefining
keyword 'co_yield'" "" { target c++20 } }
+#undef decltype // { dg-warning "undefining
keyword 'decltype'" "" { target c++11 } }
+#undef default // { dg-warning "undefining keyword
'default'" }
+#undef delete // { dg-warning "undefining keyword
'delete'" }
+#undef do // { dg-warning "undefining keyword
'do'" }
+#undef double // { dg-warning "undefining keyword
'double'" }
+#undef dynamic_cast // { dg-warning "undefining keyword
'dynamic_cast'" }
+#undef else // { dg-warning "undefining keyword
'else'" }
+#undef enum // { dg-warning "undefining keyword
'enum'" }
+#undef explicit // { dg-warning "undefining
keyword 'explicit'" }
+#undef export // { dg-warning "undefining keyword
'export'" }
+#undef extern // { dg-warning "undefining keyword
'extern'" }
+#undef false // { dg-warning "undefining keyword
'false'" }
+#undef float // { dg-warning "undefining keyword
'float'" }
+#undef for // { dg-warning "undefining keyword
'for'" }
+#undef friend // { dg-warning "undefining keyword
'friend'" }
+#undef goto // { dg-warning "undefining keyword
'goto'" }
+#undef if // { dg-warning "undefining keyword
'if'" }
+#undef inline // { dg-warning "undefining keyword
'inline'" }
+#undef int // { dg-warning "undefining keyword
'int'" }
+#undef long // { dg-warning "undefining keyword
'long'" }
+#undef mutable // { dg-warning "undefining keyword
'mutable'" }
+#undef namespace // { dg-warning "undefining keyword
'namespace'" }
+#undef new // { dg-warning "undefining keyword
'new'" }
+#undef noexcept // { dg-warning "undefining
keyword 'noexcept'" "" { target c++11 } }
+#undef nullptr // { dg-warning "undefining keyword
'nullptr'" "" { target c++11 } }
+#undef operator // { dg-warning "undefining
keyword 'operator'" }
+#undef private // { dg-warning "undefining keyword
'private'" }
+#undef protected // { dg-warning "undefining keyword
'protected'" }
+#undef public // { dg-warning "undefining keyword
'public'" }
+#undef register // { dg-warning "undefining
keyword 'register'" }
+#undef reinterpret_cast // { dg-warning "undefining
keyword 'reinterpret_cast'" }
+#undef requires // { dg-warning "undefining
keyword 'requires'" "" { target c++20 } }
+#undef return // { dg-warning "undefining keyword
'return'" }
+#undef short // { dg-warning "undefining keyword
'short'" }
+#undef signed // { dg-warning "undefining keyword
'signed'" }
+#undef sizeof // { dg-warning "undefining keyword
'sizeof'" }
+#undef static // { dg-warning "undefining keyword
'static'" }
+#undef static_assert // { dg-warning "undefining keyword
'static_assert'" "" { target c++11 } }
+#undef static_cast // { dg-warning "undefining keyword
'static_cast'" }
+#undef struct // { dg-warning "undefining keyword
'struct'" }
+#undef switch // { dg-warning "undefining keyword
'switch'" }
+#undef template // { dg-warning "undefining
keyword 'template'" }
+#undef this // { dg-warning "undefining keyword
'this'" }
+#undef thread_local // { dg-warning "undefining keyword
'thread_local'" "" { target c++11 } }
+#undef throw // { dg-warning "undefining keyword
'throw'" }
+#undef true // { dg-warning "undefining keyword
'true'" }
+#undef try // { dg-warning "undefining keyword
'try'" }
+#undef typedef // { dg-warning "undefining keyword
'typedef'" }
+#undef typeid // { dg-warning "undefining keyword
'typeid'" }
+#undef typename // { dg-warning "undefining
keyword 'typename'" }
+#undef union // { dg-warning "undefining keyword
'union'" }
+#undef unsigned // { dg-warning "undefining
keyword 'unsigned'" }
+#undef using // { dg-warning "undefining keyword
'using'" }
+#undef virtual // { dg-warning "undefining keyword
'virtual'" }
+#undef void // { dg-warning "undefining keyword
'void'" }
+#undef volatile // { dg-warning "undefining
keyword 'volatile'" }
+#undef wchar_t // { dg-warning "undefining keyword
'wchar_t'" }
+#undef while // { dg-warning "undefining keyword
'while'" }
+
+// [lex.name]
+#undef final // { dg-warning "undefining keyword
'final'" "" { target c++11 } }
+#undef import // { dg-warning "undefining keyword
'import'" "" { target c++20 } }
+#undef module // { dg-warning "undefining keyword
'module'" "" { target c++20 } }
+#undef override // { dg-warning "undefining
keyword 'override'" "" { target c++11 } }
+#undef post
+#undef pre
+#undef replaceable_if_eligible // { dg-warning "undefining keyword
'replaceable_if_eligible'" "" { target c++26 } }
+#undef trivially_relocatable_if_eligible // { dg-warning "undefining
keyword 'trivially_relocatable_if_eligible'" "" { target c++26 } }
+
+// [dcl.attr]
+#undef assume // { dg-warning "undefining keyword
'assume'" "" { target c++23 } }
+#undef carries_dependency // { dg-warning "undefining keyword
'carries_dependency'" "" { target { c++11 && c++23_down } } }
+#undef deprecated // { dg-warning "undefining keyword
'deprecated'" "" { target c++14 } }
+#undef fallthrough // { dg-warning "undefining keyword
'fallthrough'" "" { target c++17 } }
+#undef indeterminate
+#undef likely // { dg-warning "undefining keyword
'likely'" "" { target c++20 } }
+#undef maybe_unused // { dg-warning "undefining keyword
'maybe_unused'" "" { target c++17 } }
+#undef nodiscard // { dg-warning "undefining keyword
'nodiscard'" "" { target c++17 } }
+#undef noreturn // { dg-warning "undefining
keyword 'noreturn'" "" { target c++11 } }
+#undef no_unique_address // { dg-warning "undefining keyword
'no_unique_address'" "" { target c++20 } }
+#undef unlikely // { dg-warning "undefining
keyword 'unlikely'" "" { target c++20 } }
--- gcc/testsuite/g++.dg/warn/Wkeyword-macro-9.C.jj 2025-07-31
15:43:11.978543665 +0200
+++ gcc/testsuite/g++.dg/warn/Wkeyword-macro-9.C 2025-07-31
17:39:50.651062289 +0200
@@ -0,0 +1,22 @@
+// C++26 P2843R3 - Preprocessing is never undefined
+// [cpp.replace.general]/9
+// { dg-do preprocess }
+// { dg-options "-pedantic-errors" }
+
+#undef for // { dg-error "undefining keyword
'for'" "" { target c++26 } }
+#define for for // { dg-error "keyword 'for'
defined as macro" "" { target c++26 } }
+#undef for // { dg-error "undefining keyword
'for'" "" { target c++26 } }
+#define while do // { dg-error "keyword 'while' defined
as macro" "" { target c++26 } }
+#define while do // { dg-error "keyword 'while' defined
as macro" "" { target c++26 } }
+#define while for // { dg-error "keyword 'while' defined
as macro" "" { target c++26 } }
+ // { dg-error "'while' redefined" "" {
target *-*-* } .-1 }
+#undef while // { dg-error "undefining keyword
'while'" "" { target c++26 } }
+#define while while // { dg-error "keyword 'while' defined
as macro" "" { target c++26 } }
+#define private public // { dg-error "keyword 'private'
defined as macro" "" { target c++26 } }
+#define inline // { dg-error "keyword 'inline' defined
as macro" "" { target c++26 } }
+#undef inline // { dg-error "undefining keyword
'inline'" "" { target c++26 } }
+#define inline __inline__ __attribute__((__always_inline__)) // { dg-error
"keyword 'inline' defined as macro" "" { target c++26 } }
+#define likely(a) a
+#undef likely // { dg-error "undefining keyword
'likely'" "" { target c++26 } }
+#define unlikely(a, b, c) a + b + c
+#define unlikely(a, b, c) a + b + c
--- gcc/testsuite/g++.dg/warn/Wkeyword-macro-10.C.jj 2025-07-31
15:56:31.629051731 +0200
+++ gcc/testsuite/g++.dg/warn/Wkeyword-macro-10.C 2025-07-31
17:39:57.260975886 +0200
@@ -0,0 +1,23 @@
+// C++26 P2843R3 - Preprocessing is never undefined
+// [cpp.replace.general]/9
+// { dg-do preprocess }
+// { dg-options "-Wkeyword-macro" }
+
+#undef for // { dg-warning "undefining keyword
'for'" }
+#define for for // { dg-warning "keyword 'for'
defined as macro" }
+#undef for // { dg-warning "undefining keyword
'for'" }
+#define while do // { dg-warning "keyword 'while'
defined as macro" }
+#define while do // { dg-warning "keyword 'while'
defined as macro" }
+#define while for // { dg-warning "keyword 'while'
defined as macro" }
+ // { dg-warning "'while' redefined" ""
{ target *-*-* } .-1 }
+#undef while // { dg-warning "undefining keyword
'while'" }
+#define while while // { dg-warning "keyword 'while'
defined as macro" }
+#define private public // { dg-warning "keyword 'private'
defined as macro" }
+#define inline // { dg-warning "keyword 'inline'
defined as macro" }
+#undef inline // { dg-warning "undefining keyword
'inline'" }
+#define inline __inline__ __attribute__((__always_inline__)) // { dg-warning
"keyword 'inline' defined as macro" }
+#define likely(a) a
+#undef likely // { dg-warning "undefining keyword
'likely'" "" { target c++20 } }
+#define unlikely(a, b, c) a + b + c
+#define unlikely(a, b, c) a + b + c
+#undef unlikely // { dg-warning "undefining
keyword 'unlikely'" "" { target c++20 } }
--- gcc/testsuite/g++.dg/opt/pr82577.C.jj 2020-01-14 20:02:46.894608171
+0100
+++ gcc/testsuite/g++.dg/opt/pr82577.C 2025-07-31 21:45:44.750773652 +0200
@@ -3,7 +3,9 @@
#if __cplusplus > 201500L
// register is no longer a keyword in C++17.
-#define register
+#define reg
+#else
+#define reg register
#endif
class a {
@@ -14,8 +16,8 @@ struct c {
int d;
a e;
} f;
-void fn1(register c *g) {
- register int *h;
+void fn1(reg c *g) {
+ reg int *h;
do
(h) = g->e.b() + (g)->d;
while (&f);
--- gcc/testsuite/g++.dg/modules/atom-preamble-3.C.jj 2020-12-22
23:50:17.055972539 +0100
+++ gcc/testsuite/g++.dg/modules/atom-preamble-3.C 2025-07-31
21:47:42.280256294 +0200
@@ -1,4 +1,4 @@
-// { dg-additional-options "-fmodules-ts" }
+// { dg-additional-options "-fmodules-ts -Wno-keyword-macro" }
#define import import
import malcolm; // { dg-error "object-like macro" }
// { dg-error "failed to read" "" { target *-*-* } 0 }
--- gcc/testsuite/g++.dg/template/sfinae17.C.jj 2020-01-14 20:02:46.956607242
+0100
+++ gcc/testsuite/g++.dg/template/sfinae17.C 2025-07-31 21:46:45.039000604
+0200
@@ -1,7 +1,7 @@
// The conversion from D* to B* is ambiguous, but that should not produce
// an error, it should remove the first f overload by SFINAE.
-#define static_assert(TEST,STR) \
+#define my_static_assert(TEST,STR) \
do { int ar[(TEST)?1:-1]; } while (0);
struct B {};
@@ -23,6 +23,6 @@ template <class T>
int main()
{
- static_assert(sizeof f<int>(0) == sizeof(two), "");
- static_assert(sizeof f<B *>(0) == sizeof(two), "");
+ my_static_assert(sizeof f<int>(0) == sizeof(two), "");
+ my_static_assert(sizeof f<B *>(0) == sizeof(two), "");
}
--- libcpp/include/cpplib.h.jj 2025-08-01 08:36:02.967950713 +0200
+++ libcpp/include/cpplib.h 2025-08-01 10:52:12.868732832 +0200
@@ -620,6 +620,9 @@ struct cpp_options
/* True if -finput-charset= option has been used explicitly. */
bool cpp_input_charset_explicit;
+ /* True if -Wkeyword-macro. */
+ bool cpp_warn_keyword_macro;
+
/* -Wleading-whitespace= value. */
unsigned char cpp_warn_leading_whitespace;
@@ -757,7 +760,8 @@ enum cpp_warning_reason {
CPP_W_HEADER_GUARD,
CPP_W_PRAGMA_ONCE_OUTSIDE_HEADER,
CPP_W_LEADING_WHITESPACE,
- CPP_W_TRAILING_WHITESPACE
+ CPP_W_TRAILING_WHITESPACE,
+ CPP_W_KEYWORD_MACRO
};
/* Callback for header lookup for HEADER, which is the name of a
@@ -1250,6 +1254,17 @@ inline bool cpp_fun_like_macro_p (cpp_ha
return cpp_user_macro_p (node) && node->value.macro->fun_like;
}
+/* Return true for nodes marked for -Wkeyword-macro diagnostics. */
+inline bool cpp_keyword_p (cpp_hashnode *node)
+{
+ /* As keywords are marked identifiers which don't start with underscore
+ or start with underscore followed by capital letter (except for
+ _Pragma). */
+ return ((node->flags & NODE_WARN)
+ && (NODE_NAME (node)[0] != '_'
+ || (NODE_NAME (node)[1] != '_' && NODE_NAME (node)[1] != 'P')));
+}
+
extern const unsigned char *cpp_macro_definition (cpp_reader *, cpp_hashnode
*);
extern const unsigned char *cpp_macro_definition (cpp_reader *, cpp_hashnode *,
const cpp_macro *);
--- libcpp/directives.cc.jj 2025-08-01 08:36:02.929951218 +0200
+++ libcpp/directives.cc 2025-08-01 10:54:50.025660496 +0200
@@ -734,13 +734,30 @@ do_undef (cpp_reader *pfile)
if (pfile->cb.undef)
pfile->cb.undef (pfile, pfile->directive_line, node);
+ /* Handle -Wkeyword-macro registered identifiers. */
+ bool diagnosed = false;
+ if (CPP_OPTION (pfile, cpp_warn_keyword_macro) && cpp_keyword_p (node))
+ {
+ if (CPP_OPTION (pfile, cpp_pedantic)
+ && CPP_OPTION (pfile, cplusplus)
+ && CPP_OPTION (pfile, lang) >= CLK_GNUCXX26)
+ cpp_pedwarning (pfile, CPP_W_KEYWORD_MACRO,
+ "undefining keyword %qs", NODE_NAME (node));
+ else
+ cpp_warning (pfile, CPP_W_KEYWORD_MACRO,
+ "undefining keyword %qs", NODE_NAME (node));
+ diagnosed = true;
+ }
/* 6.10.3.5 paragraph 2: [#undef] is ignored if the specified
identifier is not currently defined as a macro name. */
if (cpp_macro_p (node))
{
if (node->flags & NODE_WARN)
- cpp_error (pfile, CPP_DL_WARNING,
- "undefining %qs", NODE_NAME (node));
+ {
+ if (!diagnosed)
+ cpp_error (pfile, CPP_DL_WARNING,
+ "undefining %qs", NODE_NAME (node));
+ }
else if (cpp_builtin_macro_p (node)
&& CPP_OPTION (pfile, warn_builtin_macro_redefined))
cpp_warning (pfile, CPP_W_BUILTIN_MACRO_REDEFINED,
--- libcpp/macro.cc.jj 2025-08-01 08:36:02.990950406 +0200
+++ libcpp/macro.cc 2025-08-01 10:54:25.112989006 +0200
@@ -3408,7 +3408,11 @@ warn_of_redefinition (cpp_reader *pfile,
{
/* Some redefinitions need to be warned about regardless. */
if (node->flags & NODE_WARN)
- return true;
+ {
+ /* Ignore NODE_WARN on -Wkeyword-macro registered identifiers though. */
+ if (!CPP_OPTION (pfile, cpp_warn_keyword_macro) || !cpp_keyword_p (node))
+ return true;
+ }
/* Suppress warnings for builtins that lack the NODE_WARN flag,
unless Wbuiltin-macro-redefined. */
@@ -3946,6 +3950,25 @@ _cpp_create_definition (cpp_reader *pfil
if (name_loc)
macro->line = name_loc;
+ /* Handle -Wkeyword-macro registered identifiers. */
+ if (CPP_OPTION (pfile, cpp_warn_keyword_macro) && cpp_keyword_p (node))
+ {
+ if (macro->fun_like
+ && CPP_OPTION (pfile, cplusplus)
+ && (strcmp ((const char *) NODE_NAME (node), "likely") == 0
+ || strcmp ((const char *) NODE_NAME (node), "unlikely") == 0))
+ /* likely and unlikely can be defined as function-like macros. */;
+ else if (CPP_OPTION (pfile, cpp_pedantic)
+ && CPP_OPTION (pfile, cplusplus)
+ && CPP_OPTION (pfile, lang) >= CLK_GNUCXX26)
+ cpp_pedwarning_with_line (pfile, CPP_W_KEYWORD_MACRO, macro->line, 0,
+ "keyword %qs defined as macro",
+ NODE_NAME (node));
+ else
+ cpp_warning_with_line (pfile, CPP_W_KEYWORD_MACRO, macro->line, 0,
+ "keyword %qs defined as macro",
+ NODE_NAME (node));
+ }
if (cpp_macro_p (node))
{
if (CPP_OPTION (pfile, warn_unused_macros))
@@ -3954,12 +3977,12 @@ _cpp_create_definition (cpp_reader *pfil
if (warn_of_redefinition (pfile, node, macro))
{
const enum cpp_warning_reason reason
- = (cpp_builtin_macro_p (node) && !(node->flags & NODE_WARN))
- ? CPP_W_BUILTIN_MACRO_REDEFINED : CPP_W_NONE;
+ = (cpp_builtin_macro_p (node) && !(node->flags & NODE_WARN)
+ ? CPP_W_BUILTIN_MACRO_REDEFINED : CPP_W_NONE);
bool warned
- = cpp_pedwarning_with_line (pfile, reason, macro->line, 0,
- "%qs redefined", NODE_NAME (node));
+ = cpp_pedwarning_with_line (pfile, reason, macro->line, 0,
+ "%qs redefined", NODE_NAME (node));
if (warned && cpp_user_macro_p (node))
cpp_error_with_line (pfile, CPP_DL_NOTE, node->value.macro->line,
Jakub
