Re: [PATCH] scripts/kernel-doc: fix make htmldoc warning

[Akira Yokosawa <akiyks@gmail.com>]

Hi,

On Date: Sun, 29 Oct 2023 12:06:58 -0600, Jonathan Corbet wrote:
> Swarup Laxman Kotiaklapudi <swarupkotikalapudi@gmail.com> writes:
> 
>> make htmldocs has below warnings:
>>
>> ..
>> Variable length lookbehind is experimental in regex;
>> marked by <-- HERE in m/(?<=^|\s)-Werror(?=$|\s)
>> <-- HERE / at ./scripts/kernel-doc line 188.
>> ...
> 
> So how do you get this warning?  I've not seen it.  Which version of
> Perl? 

I get this warning on Ubuntu 22.04LTS, whose perl is v5.34.0.

Swarup's change silences the warning there.

I could provide a tested-by: tag if I was familiar with that
"variable length lookbehind" thing ...

        Thanks, Akira

> 
>> "-Werror" option in make command,
>> needs "-Werror" to have space before
>> and after while running make command,
>> hence space checking is sepratly done,
>> and is not part of lookbehind regular expression.
>>
>> Below command also didn't
>> show any error:
>>  make KCFLAGS="-Werror=return-type" W=1 kernel/fork.o
>>
>> Fixes: 91f950e8b9d8 ("scripts/kernel-doc: match -Werror flag strictly")
>> Signed-off-by: Swarup Laxman Kotiaklapudi <swarupkotikalapudi@gmail.com>
>> ---
>>  scripts/kernel-doc | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/scripts/kernel-doc b/scripts/kernel-doc
>> index d660e1f4b483..aa9e3e198d12 100755
>> --- a/scripts/kernel-doc
>> +++ b/scripts/kernel-doc
>> @@ -185,7 +185,7 @@ if (defined($ENV{'KBUILD_VERBOSE'}) && $ENV{'KBUILD_VERBOSE'} =~ '1') {
>>  if (defined($ENV{'KCFLAGS'})) {
>>  	my $kcflags = "$ENV{'KCFLAGS'}";
>>  
>> -	if ($kcflags =~ /(?<=^|\s)-Werror(?=$|\s)/) {
>> +	if ($kcflags =~ /(?<=^|)(\s)-Werror(?=$|)(\s)/) {
>>  		$Werror = 1;
>>  	}
>>  }
> 
> Thanks,
> 
> jon