linux-kernel - Re: Kconfig: '+config' valid syntax?

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Message-ID: <CAEMqcmoTHxOGRdRFMrY=kkG4HzD7vNUHVwZCsGDabGUOxhsvOQ@mail.gmail.com>
Date:	Fri, 3 Jul 2015 12:46:24 +0200
From:	Ulf Magnusson <ulfalizer.lkml@...il.com>
To:	Andreas Ruprecht <andreas.ruprecht@....de>
Cc:	Paul Bolle <pebolle@...cali.nl>,
	Valentin Rothberg <valentinrothberg@...il.com>,
	rafael.j.wysocki@...el.com, linux-kbuild@...r.kernel.org,
	Kernel Mailing List <linux-kernel@...r.kernel.org>,
	hengelein Stefan <stefan.hengelein@....de>,
	linux@...inikbrodowski.net
Subject: Re: Kconfig: '+config' valid syntax?

On Fri, Jul 3, 2015 at 11:29 AM, Andreas Ruprecht
<andreas.ruprecht@....de> wrote:
> On 07/03/2015 10:59, Paul Bolle wrote:
>> On vr, 2015-07-03 at 09:33 +0200, Andreas Ruprecht wrote:
>>> I tested the behaviour on yesterday's linux-next, but the commit
>>> mentioned above will only complain for invalid characters inside the
>>> PARAM case and not for COMMANDs. So, as an example, if you write
>>> something like
>>>
>>> config ACPI_REV_OVERRIDE_POSSIBLE
>>>      depends on X86 +
>>> [...]
>>>
>>> Kconfig will complain about the '+'. This, however, does not apply for
>>> top-level statements like 'config', 'menuconfig', and so on.
>>
>> Which might explain why this silly mistake went unnoticed. (And, as I
>> think you implied, it doesn't help that the empty rule we're hitting
>> here is not commented.)
>>
>> So the naive solution seems to be to also add the warning to COMMAND's
>> rule for '.'. A quick test suggest that would work. Am I missing some
>> obvious downside with that solution?
>
> Well, as I mentioned earlier, with a patch similar to the one below this
> warning is also generated three times for every '---' before 'help'.
> This results in a giant pile of warnings:
>
> ruprecht@box:linux-next$ rm -f scripts/kconfig/*_shipped &&
> REGENERATE_PARSERS=1 make allyesconfig 2>&1 | wc -l
> 7419
>
> The output looks like this:
> scripts/kconfig/conf  --allyesconfig Kconfig
> arch/x86/Kconfig:4:warning: ignoring unsupported character '-'
> arch/x86/Kconfig:4:warning: ignoring unsupported character '-'
> arch/x86/Kconfig:4:warning: ignoring unsupported character '-'
> init/Kconfig:222:warning: ignoring unsupported character '-'
> init/Kconfig:222:warning: ignoring unsupported character '-'
> init/Kconfig:222:warning: ignoring unsupported character '-'
> init/Kconfig:244:warning: ignoring unsupported character '-'
> init/Kconfig:244:warning: ignoring unsupported character '-'
> init/Kconfig:244:warning: ignoring unsupported character '-'
> [...]
>
> So we would need to add special treatment for '-' also in the command
> case, right? But that doesn't look appealing to me, more like a dirty,
> dirty hack around the actual problem...
>
> Regards,
>
> Andreas
>

Except for scattered accidents like in the original message, which are
hopefully pretty rare and easy to fix, the only documented thing that depends
on that lexer sloppiness is the ---help--- "token".

I'd just add "---help---" as another T_HELP alias (or get rid of it altogether,
but that's probably more work than it's worth). Tightening things up should be
safe after that.

/Ulf
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