linux-kernel - Re: [PATCH] kconfig: fix relational operators for bool and tristate symbols

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Date:   Wed, 6 Dec 2017 12:24:36 -0800
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Nicolas Pitre <nicolas.pitre@...aro.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Michal Marek <michal.lkml@...kovi.net>,
        Jan Beulich <JBeulich@...e.com>
Cc:     Arnd Bergmann <arnd@...db.de>, linux-kbuild@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kconfig: fix relational operators for bool and tristate
 symbols

On 12/06/2017 07:40 AM, Nicolas Pitre wrote:
> 
> Ping.
> 
> On Thu, 16 Nov 2017, Nicolas Pitre wrote:
> 
>> Since commit 31847b67bec0 ("kconfig: allow use of relations other than
>> (in)equality") it is possible to use relational operators in Kconfig
>> statements. However, those operators give unexpected results when
>> applied to bool/tristate values:
>>
>> 	(n < y) = y (correct)
>> 	(m < y) = y (correct)
>> 	(n < m) = n (wrong)
>>
>> This happens because relational operators process bool and tristate
>> symbols as strings and m sorts before n. It makes little sense to do a
>> lexicographical compare on bool and tristate values though.
>>
>> Documentation/kbuild/kconfig-language.txt states that expression can have
>> a value of 'n', 'm' or 'y' (or 0, 1, 2 respectively for calculations).
>> Let's make it so for relational comparisons with bool/tristate
>> expressions as well and document them. If at least one symbol is an
>> actual string then the lexicographical compare works just as before.
>>
>> Signed-off-by: Nicolas Pitre <nico@...aro.org>

Acked-by: Randy Dunlap <rdunlap@...radead.org>
Tested-by: Randy Dunlap <rdunlap@...radead.org>


-- 
~Randy