Re: Font-lock decides function call is function declaration in C+ + - Patch

Re: Font-lock decides function call is function declaration in C+ + - Patch

[Alan Mackenzie]

Hi, Chong and Simon

On Thu, Mar 01, 2007 at 12:19:57PM -0500, Chong Yidong wrote:
> Hi Alan,

> Judging by the size of the patch you sent, and the time it's taking to
> write it, this seems to be a lot of work.  Once we include the time
> necessary for testing such a big change, it will probably
> significantly delay the Emacs 22 release.

int main () {
    foo         <===== type "();", then erase it.
    bar ();
}

I've just committed a patch to cc-mode.el and cc-engine.el which fixes
Simon's (first) bug.  [The "variant" he mentioned is a distinct bug.]

It's a fairly scrappy ad-hoc patch - it fixes a particular simple bug
scenario which will surely occur frequently.  Its idea is to remove
tokens from the cache `c-found-types' whenever these tokens are broken
up (e.g. by typing stuff in the middle of them, or removing space which
separated them from other tokens) or when their syntactic identity as
types ceases is disrupted.

I think this cache mechanism should to be thought through and either
abolished or amended to work consistently.

-- 
Alan Mackenzie (Ittersbach Germany).

Re: Font-lock decides function call is function declaration in C+ + - Patch

[Chong Yidong]

Alan Mackenzie <acm@muc.de> writes:

> It's a fairly scrappy ad-hoc patch - it fixes a particular simple bug
> scenario which will surely occur frequently.  Its idea is to remove
> tokens from the cache `c-found-types' whenever these tokens are broken
> up (e.g. by typing stuff in the middle of them, or removing space which
> separated them from other tokens) or when their syntactic identity as
> types ceases is disrupted.
>
> I think this cache mechanism should to be thought through and either
> abolished or amended to work consistently.

Thanks.

Re: Font-lock decides function call is function declaration in C+ + - Patch

[Richard Stallman]

    It's a fairly scrappy ad-hoc patch - it fixes a particular simple bug
    scenario which will surely occur frequently.

What I worry about is, how likely is it to cause new bugs in other
cases?

It would be safer just to turn off this cache feature.
How much would users mind that?

Re: Font-lock decides function call is function declaration in C+ + - Patch

[Alan Mackenzie]

Hi, Richard!

On Fri, Mar 09, 2007 at 04:25:35PM -0500, Richard Stallman wrote:
>     It's a fairly scrappy ad-hoc patch - it fixes a particular simple bug
>     scenario which will surely occur frequently.

> What I worry about is, how likely is it to cause new bugs in other
> cases?

I was worrying about that all the time I was formulating the bug and
writing the patch.  The answer is, IMBO[*], not very likely.  Here's my
analysis:

(i) The patch doesn't change the buffer contents (apart from, possibly,
text properties on some characters).  It intended effect is purely to
remove type-identifiers from the cache `c-found-types'.  Removing a type
from this cache when it should stay there wouldn't be that bad.  Failing
to remove a stale type would be no worse than the code prior to the fix.

(ii) Bugs like going off the end of a buffer, getting lisp errors with
empty buffers, and such like, are possible.

(iii) Bugs like forgetting to widen are possible.

[*] "In my biassed opion"

> It would be safer just to turn off this cache feature.

That would throw out some of the fontification, and would slow things
down.  I don't know by how much; I would guess quite a lot.

> How much would users mind that?

I would guess some (like Simon ;-) would mind a lot.  Others (like me)
would hardly notice.  I think, in general, it wouldn't be good to take
this cache out, now.  It's been in place since CC Mode 5.30 (summer
2003).

How about letting Simon test it on his C++ code?

-- 
Alan Mackenzie (Ittersbach, Germany).

Re: Font-lock decides function call is function declaration in C+ + - Patch

[Richard Stallman]

I guess we are stuck with this fix.

RE: Font-lock decides function call is function declaration in C+ + - Patch

[Marshall, Simon]

> > It would be safer just to turn off this cache feature.

Unfortunately, I don't think cc-model honours c++-font-lock-extra-types
anymore.  That was an old way of teaching font-lock about C++ types for
fontification purposes.  It's still defined, just no longer used.

> How about letting Simon test it on his C++ code?

I can't right now, as cvs.savannah.gnu.org seems uncooperative:

> cvs update
cvs [update aborted]: reading from server: Connection reset by peer
> cat CVS/Root 
:pserver:anonymous@cvs.savannah.gnu.org:/sources/emacs
> ping cvs.savannah.gnu.org
cvs.savannah.gnu.org is alive
> 


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