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From: Jonathan Corbet <corbet@lwn.net>
To: Swarup Laxman Kotiaklapudi <swarupkotikalapudi@gmail.com>,
 yujie.liu@intel.com, linux-doc@vger.kernel.org,
 swarupkotikalapudi@gmail.com,
 linux-kernel-mentees@lists.linuxfoundation.org
Subject: Re: [PATCH] scripts/kernel-doc: fix make htmldoc warning
In-Reply-To: <20231028182231.123996-1-swarupkotikalapudi@gmail.com>
References: <20231028182231.123996-1-swarupkotikalapudi@gmail.com>
Date: Sun, 29 Oct 2023 12:06:58 -0600
Message-ID: <87a5s15mm5.fsf@meer.lwn.net>
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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? 

> "-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