linux-kernel - Re: [PATCH v3 01/56] scripts: kernel-doc: fix typedef parsing

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Date:   Sat, 24 Oct 2020 08:43:05 +0200
From:   Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
To:     Jonathan Corbet <corbet@....net>
Cc:     Linux Doc Mailing List <linux-doc@...r.kernel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 01/56] scripts: kernel-doc: fix typedef parsing

Em Fri, 23 Oct 2020 11:22:26 -0600
Jonathan Corbet <corbet@....net> escreveu:

> On Fri, 23 Oct 2020 18:32:48 +0200
> Mauro Carvalho Chehab <mchehab+huawei@...nel.org> wrote:
> 
> > The include/linux/genalloc.h file defined this typedef:
> > 
> > 	typedef unsigned long (*genpool_algo_t)(unsigned long *map,unsigned long size,unsigned long start,unsigned int nr,void *data, struct gen_pool *pool, unsigned long start_addr);
> > 
> > Because it has a type composite of two words (unsigned long),
> > the parser gets the typedef name wrong:
> > 
> > .. c:macro:: long
> > 
> >    **Typedef**: Allocation callback function type definition
> > 
> > Fix the regex in order to accept composite types when
> > defining a typedef for a function pointer.
> > 
> > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
> > ---
> >  scripts/kernel-doc | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/scripts/kernel-doc b/scripts/kernel-doc
> > index 99cd8418ff8a..311d213ee74d 100755
> > --- a/scripts/kernel-doc
> > +++ b/scripts/kernel-doc
> > @@ -1438,7 +1438,7 @@ sub dump_typedef($$) {
> >      $x =~ s@/\*.*?\*/@@gos;	# strip comments.
> >  
> >      # Parse function prototypes
> > -    if ($x =~ /typedef\s+(\w+)\s*\(\*\s*(\w\S+)\s*\)\s*\((.*)\);/ ||
> > +    if ($x =~ /typedef\s+(\w+\s*){1,}\(\*\s*(\w\S+)\s*\)\s*\((.*)\);/ ||  
> 
> I sure wish we could find a way to make all these regexes more
> understandable and maintainable.  Reviewing a change like this is ... fun.

Yeah. Regexes can be take a while to check. Btw, there's a site that
is really cool to check things:

	https://regex101.com/

Unfortunately, it doesn't support Perl flavor. So, you may still
need to double-check if Perl will handle the regex the same way[1].

[1] One of the differences I found is with regards to match repetitions
    https://perldoc.perl.org/perlrequick#Matching-repetitions
    This works on both Python and Perl:
	(foo){0,2}
    But this only works on Python:
	(foo){,2}

> 
> Anyway, it seems to work, but it does now include trailing whitespace in
> the type portion.  So, for example, from include/linux/xarray.h:
> 
>   typedef void (*xa_update_node_t)(struct xa_node *node);
> 
> The type is parsed as "void " where it was "void" before.  The only ill
> effect I can see is that some non-breaking spaces get inserted into the
> HTML output, but perhaps it's worth stripping off that trailing space
> anyway?

Ok, I'll work on a second version addressing it.

Thanks,
Mauro