Message-ID: <20160615190804.GY11948@wotan.suse.de>
Date:	Wed, 15 Jun 2016 21:08:04 +0200
From:	"Luis R. Rodriguez" <mcgrof@...nel.org>
To:	Julia Lawall <julia.lawall@...6.fr>
Cc:	"Luis R. Rodriguez" <mcgrof@...nel.org>,
	Gilles Muller <Gilles.Muller@...6.fr>, nicolas.palix@...g.fr,
	mmarek@...e.com, linux-kernel@...r.kernel.org,
	cocci@...teme.lip6.fr
Subject: Re: [PATCH 4/4] scripts/coccinelle: require coccinelle >= 1.0.4 on
 device_node_continue.cocci

On Wed, Jun 15, 2016 at 06:52:27PM +0200, Julia Lawall wrote:
> 
> 
> On Wed, 15 Jun 2016, Luis R. Rodriguez wrote:
> 
> > On Wed, Jun 15, 2016 at 06:11:57PM +0200, Julia Lawall wrote:
> > >
> > >
> > > On Wed, 15 Jun 2016, Luis R. Rodriguez wrote:
> > >
> > > > On Wed, Jun 15, 2016 at 05:55:34PM +0200, Julia Lawall wrote:
> > > > >
> > > > >
> > > > > On Wed, 15 Jun 2016, Luis R. Rodriguez wrote:
> > > > >
> > > > > > On Wed, Jun 15, 2016 at 10:43:30AM +0200, Julia Lawall wrote:
> > > > > > > How about the following, since Coccinelle knows what its version is?
> > > > > > > This could of course be implemented in python as well.
> > > > > > >
> > > > > > > julia
> > > > > > >
> > > > > > > diff --git a/docs/Coccilib.3cocci b/docs/Coccilib.3cocci
> > > > > > > index 0e4fbb8..ca5b061 100644
> > > > > > > --- a/docs/Coccilib.3cocci
> > > > > > > +++ b/docs/Coccilib.3cocci
> > > > > > > @@ -232,6 +232,15 @@ is the empty list if spatch is not currently working on any file (eg,
> > > > > > >  in an initialize or finalize rule).
> > > > > > >  .sp
> > > > > > >
> > > > > > > +.I val cocci_version
> > > > > > > +:
> > > > > > > +.B unit -> string
> > > > > > > +.sp
> > > > > > > +Returns the a string indicating the current version.  Note that if
> > > > > > > +Coccinelle has been modified since a release, the version number will be
> > > > > > > +postfixed with "-dirty".
> > > > > > > +.sp
> > > > > > > +
> > > > > > >  .I val print_main
> > > > > > >  :
> > > > > > >  .B ?color:string -> string -> pos list -> unit
> > > > > > > diff --git a/ocaml/coccilib.ml b/ocaml/coccilib.ml
> > > > > > > index f60c6b2..2f352d8 100644
> > > > > > > --- a/ocaml/coccilib.ml
> > > > > > > +++ b/ocaml/coccilib.ml
> > > > > > > @@ -168,6 +168,8 @@ let dir () = !Flag.dir
> > > > > > >
> > > > > > >  let files () = !Flag.currentfiles
> > > > > > >
> > > > > > > +let cocci_version () = Config.version
> > > > > > > +
> > > > > > >  (* ---------------------------------------------------------------------- *)
> > > > > > >  (* org mode *)
> > > > > > >
> > > > > > >
> > > > > >
> > > > > > Anything to *only* get the version instead of a long list is nice, right now
> > > > > > spatch --version spits out:
> > > > > >
> > > > > > spatch version 1.0.5 compiled with OCaml version 4.02.3
> > > > > > Flags passed to the configure script: [none]
> > > > > > Python scripting support: yes
> > > > > > Syntax of regular expresssions: PCRE
> > > > > >
> > > > > > The Python library just parses the 3rd item at the top so it can extract
> > > > > > the version. But surely if spatch --version-only was available we'd use
> > > > > > that instead a well.
> > > > > >
> > > > > > Other than this though how can we require coccinelle version checks per
> > > > > > SmPL file cleanly and also what should we do to make it backward compatible
> > > > > > with older versions of coccinelle?
> > > > >
> > > > > I'm not sure that being backward compatible with older versions of
> > > > > Coccinelle is worth adding new libraries to the Linux kernel, and adding
> > > > > unpleasant python code to semantic patches.
> > > >
> > > > True. I'm more than happy to not have to add this crap.
> > > >
> > > > > The above ocaml code just produces eg 1.0.5 or 1.0.5-dirty.  I could drop
> > > > > the -dirty at the coccilib level, if that seems desirable.
> > > >
> > > > This is when spatch --cocci_version is passed ?
> > >
> > > Perhaps it wasn't clear enough from the above nroff and ocaml code.  I
> > > added a function Coccilib.version() that returns eg either 1.0.5 or
> > > 1.0.5-dirty.  Such a function could be implemented for python as well.
> > >
> > > >
> > > > Its still unclear how we can require in a clean way coccinelle version
> > > > requirements in SmPL patches with this. Can you clarify?
> > >
> > > Test the string that it returns and exit.  Like you are doing, but no need
> > > for adding new libraries to the kernel.
> >
> > Ah then that's indeed welcome, however another function would be best too:
> >
> > Coccilib.version_reqs() which lets us say what the requirement is and it
> > would return true or false, false when the req is not met.
> 
> I'm not so fond of this.  It seems like a very specific use case.

Perhaps.

> I really think this should be managed by coccicheck, in the same way as
> the options.

OK if its up to coccicheck -- we'll need a solution there. I'd prefer to use a
generic library like reqs there and just have the check for the maximum
requirement there.

Michal do you have any preference ?

FWIW I had originally written the reqs library for for rel-html [0] which
enables arbitrary projects to make a shiny HTLM5 release project based on a
naked release page provided, the inferring of release needs some generic
heuristics on release matching (in the future the simpler approach is
to have a git tree have two PGP signatures, one for signed releases, and
another for deprecating release, then an alternative smarter heuristic
would be to only look for signed tags of currently supported releases),
the Linux kernel's strategy on versioning computation seemed the way to go.
I was surprised no standard library supported it properly. This library is
also used on backports not only for coccinell requirements but for other
generic binary requirements.

We can bash it out.. however this seems like it could be generally useful
for other tools we have in the kernel.

[0] https://git.kernel.org/cgit/linux/kernel/git/mcgrof/rel-html.git/

  Luis

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