On 11/10/25 11:59 AM, Jakub Jelinek wrote:
Hi!
The following patch implements CWG3053 approved in Kona, where it is now
valid not just to #define likely(a) or #define unlikely(a, b, c) but also
to #undef likely or #undef unlikely.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
2025-11-10 Jakub Jelinek <[email protected]>
libcpp/
* directives.cc: Implement CWG3053.
(do_undef): Don't pedwarn or warn about #undef likely or #undef
unlikely.
gcc/testsuite/
* g++.dg/warn/Wkeyword-macro-4.C: Don't diagnose for #undef likely
or #undef unlikely.
* g++.dg/warn/Wkeyword-macro-5.C: Likewise.
* g++.dg/warn/Wkeyword-macro-9.C: Likewise.
* g++.dg/warn/Wkeyword-macro-8.C: Likewise.
* g++.dg/warn/Wkeyword-macro-10.C: Likewise.
--- libcpp/directives.cc.jj 2025-08-15 22:31:17.289081163 +0200
+++ libcpp/directives.cc 2025-11-08 09:36:29.186756709 +0100
@@ -740,9 +740,14 @@ do_undef (cpp_reader *pfile)
&& !CPP_OPTION (pfile, suppress_builtin_macro_warnings)
&& cpp_keyword_p (node))
{
- if (CPP_OPTION (pfile, cpp_pedantic)
- && CPP_OPTION (pfile, cplusplus)
- && CPP_OPTION (pfile, lang) >= CLK_GNUCXX26)
+ if (CPP_OPTION (pfile, cplusplus)
+ && (strcmp ((const char *) NODE_NAME (node), "likely") == 0
+ || strcmp ((const char *) NODE_NAME (node),
+ "unlikely") == 0))
+ /* CWG3053: likely and unlikely can be undefined. */;
+ else 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
--- gcc/testsuite/g++.dg/warn/Wkeyword-macro-4.C.jj 2025-08-07
08:47:14.108784105 +0200
+++ gcc/testsuite/g++.dg/warn/Wkeyword-macro-4.C 2025-11-08
09:39:00.091610696 +0100
@@ -104,9 +104,9 @@
#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 likely
#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 } }
+#undef unlikely
--- gcc/testsuite/g++.dg/warn/Wkeyword-macro-5.C.jj 2025-08-07
08:47:14.108784105 +0200
+++ gcc/testsuite/g++.dg/warn/Wkeyword-macro-5.C 2025-11-08
09:39:34.746117872 +0100
@@ -104,9 +104,9 @@
#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 likely
#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 } }
+#undef unlikely
--- gcc/testsuite/g++.dg/warn/Wkeyword-macro-9.C.jj 2025-08-07
08:47:14.109784091 +0200
+++ gcc/testsuite/g++.dg/warn/Wkeyword-macro-9.C 2025-11-08
09:40:00.382753292 +0100
@@ -17,6 +17,6 @@
#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 } }
+#undef likely
#define unlikely(a, b, c) a + b + c
#define unlikely(a, b, c) a + b + c
--- gcc/testsuite/g++.dg/warn/Wkeyword-macro-8.C.jj 2025-08-07
08:47:14.109784091 +0200
+++ gcc/testsuite/g++.dg/warn/Wkeyword-macro-8.C 2025-11-08
09:39:47.451937184 +0100
@@ -104,9 +104,9 @@
#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 likely
#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 } }
+#undef unlikely
--- gcc/testsuite/g++.dg/warn/Wkeyword-macro-10.C.jj 2025-08-07
08:47:14.109784091 +0200
+++ gcc/testsuite/g++.dg/warn/Wkeyword-macro-10.C 2025-11-08
09:40:14.254556023 +0100
@@ -17,7 +17,7 @@
#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 } }
+#undef likely
#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 } }
+#undef unlikely
Jakub
