Re: [patch] PR 81271: gcc/cp/lex.c:116: wrong condition ?

[Jason Merrill <jason@redhat.com>]

On 1/24/24 00:57, Jasmine Tang wrote:
> Change the style from & to && to reflect boolean result with boolean 
> operation (instead of bitwise operation)
> 
> David Binderman 2017-07-01 13:24:44 UTC
> 
> trunk/gcc/cp/lex.c:116]: (style) Boolean result is used in bitwise operation. Clarify expression with parentheses.
> 
> Source code is
> 
>    gcc_checking_assert (!IDENTIFIER_KIND_BIT_2 (id)
>                 & !IDENTIFIER_KIND_BIT_1 (id)
>                 & !IDENTIFIER_KIND_BIT_0 (id));
> 
> Maybe better code
> 
>    gcc_checking_assert (!IDENTIFIER_KIND_BIT_2 (id)
>                 && !IDENTIFIER_KIND_BIT_1 (id)
>                 && !IDENTIFIER_KIND_BIT_0 (id));
> 

Since the _BIT_n macros all produce either 0 or 1, bitwise & has the 
same meaning as &&, except possibly faster because it doesn't involve 
the shortcut semantics of &&.

I notice the warning suggests "Clarify expression with parentheses."  I 
suspect that means along the lines of IDENTIFIER_KEYWORD_P and such in 
cp-tree.h, where the ! expression is parenthesized:

> #define IDENTIFIER_KEYWORD_P(NODE)              \
>   ((!IDENTIFIER_KIND_BIT_2 (NODE))              \
>    & (!IDENTIFIER_KIND_BIT_1 (NODE))            \
>    & IDENTIFIER_KIND_BIT_0 (NODE))

Does doing that quiet the warning?

Jason