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

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Message-ID: <CAD3Xx4LSYWfeeSyEnFNgOHera9wnt2ZxBrRutzMdw2tbaC1DNw@mail.gmail.com>
Date:	Fri, 3 Jul 2015 12:51:58 +0200
From:	Valentin Rothberg <valentinrothberg@...il.com>
To:	Ulf Magnusson <ulfalizer.lkml@...il.com>
Cc:	Andreas Ruprecht <andreas.ruprecht@....de>,
	Paul Bolle <pebolle@...cali.nl>, 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 12:46 PM, Ulf Magnusson <ulfalizer.lkml@...il.com> wrote:
> 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.

This idea has a big ACK from me.  It seems to me the cleanest way to
solve the issue.

Kind regards,
 Valentin

> /Ulf
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