[PATCH] libcpp: Use [[likely]] conditionally

Christophe LYON christophe.lyon@foss.st.com
Tue Nov 23 15:26:19 GMT 2021


Hi!

On 23/11/2021 01:26, Jeff Law via Gcc-patches wrote:
>
>
> On 11/22/2021 10:22 AM, Marek Polacek via Gcc-patches wrote:
>> Let's hide [[likely]] behind a macro, to suppress warnings if the
>> compiler doesn't support it.
>>
>> Co-authored-by: Jonathan Wakely <jwakely@redhat.com>
>>
>> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>>
>>     PR preprocessor/103355
>>
>> libcpp/ChangeLog:
>>
>>     * lex.c: Use ATTR_LIKELY instead of [[likely]].
>>     * system.h (ATTR_LIKELY): Define.
> OK
> jeff


This patch breaks the build when the host compiler is gcc-4.8.5, because 
__has_cpp_attribute is not defined.

Is this small patch OK with a proper ChangeLog?


diff --git a/libcpp/system.h b/libcpp/system.h
index f6fc583ab80..b78ab813d2f 100644
--- a/libcpp/system.h
+++ b/libcpp/system.h
@@ -430,6 +430,8 @@ extern void fancy_abort (const char *, int, const 
char *) ATTRIBUTE_NORETURN;
  # else
  #  define ATTR_LIKELY
  # endif
+#else
+# define ATTR_LIKELY
  #endif

  /* Poison identifiers we do not want to use.  */


Thanks,


Christophe





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