Re: [PATCH] c: support attribs starting with '_'

["Martin Liška" <mliska@suse.cz>]

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On 10/5/22 14:01, Jakub Jelinek wrote:
> On Wed, Oct 05, 2022 at 01:49:40PM +0200, Martin Liška wrote:
>> 	PR c/107156
>>
>> gcc/ChangeLog:
>>
>> 	* attribs.h (lookup_attribute_by_prefix): Support attributes
>> 	starting with underscore (like _noreturn, or __Noreturn).
> 
> There are no _noreturn or __Noreturn attributes, there is just
> _Noreturn.
> And, the assert is useful to catch that non-canonicalized attributes
> don't make it into the attribute lists.
> Now that we have the first attribute that starts with an underscore
> in canonicalized form (do we accept ___Noreturn__ attribute too, perhaps
> we shouldn't?), I'd say instead of removing the assert it should verify
> 	gcc_checking_assert (attr_len == 0 || p[0] != '_'
> 			     || (ident_len > 1 && p[1] != '_'));

Works for me, I'm going to install the following patch.

Martin

> ?
>> ---
>>  gcc/attribs.h | 2 --
>>  1 file changed, 2 deletions(-)
>>
>> diff --git a/gcc/attribs.h b/gcc/attribs.h
>> index b2836560fc2..706d35e63d8 100644
>> --- a/gcc/attribs.h
>> +++ b/gcc/attribs.h
>> @@ -274,8 +274,6 @@ lookup_attribute_by_prefix (const char *attr_name, tree list)
>>  	    }
>>  
>>  	  const char *p = IDENTIFIER_POINTER (name);
>> -	  gcc_checking_assert (attr_len == 0 || p[0] != '_');
>> -
>>  	  if (strncmp (attr_name, p, attr_len) == 0)
>>  	    break;
>>  
>> -- 
>> 2.37.3
> 
> 	Jakub
> 

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From b7eb1e7a0e887849470ec96c5f31422b2224c461 Mon Sep 17 00:00:00 2001
From: Martin Liska <mliska@suse.cz>
Date: Wed, 5 Oct 2022 12:34:30 +0200
Subject: [PATCH] c: support the attribute starting with '_'

	PR c/107156

gcc/ChangeLog:

	* attribs.h (lookup_attribute_by_prefix): Support the attribute
	starting with underscore (_Noreturn).
---
 gcc/attribs.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/gcc/attribs.h b/gcc/attribs.h
index b2836560fc2..121b9ebbc39 100644
--- a/gcc/attribs.h
+++ b/gcc/attribs.h
@@ -274,8 +274,8 @@ lookup_attribute_by_prefix (const char *attr_name, tree list)
 	    }
 
 	  const char *p = IDENTIFIER_POINTER (name);
-	  gcc_checking_assert (attr_len == 0 || p[0] != '_');
-
+	  gcc_checking_assert (attr_len == 0 || p[0] != '_'
+			       || (ident_len > 1 && p[1] != '_'));
 	  if (strncmp (attr_name, p, attr_len) == 0)
 	    break;
 
-- 
2.37.3