Re: Backporting the Linux kernel, for good - was: Re: semantic patch inference

On Sat, 10 Sep 2011, Jesper Andersen wrote:

I'm in Singapore now and will head for Denmark tomorrow so I can't promise
very instant reponses.

I haven't read the full thread just yet, but I just wanted to clarify one
thing:

On Saturday, September 10, 2011, Julia Lawall wrote:

quoted

There was also the question about one or multiple types of changes.  I
think this is not a problem, but Jesper should confirm.  If a patch
contains
two changes and one can be generalized and the other one cannot for some
reason, does spdiff give up on the whole thing, or does it do what it can?

It's a little difficult to answer this precisely, so let me instead give an
example and then you can say in what way my example falls short of what you
thought of.

Suppose we have two functions that changed:

f1=
void foo() {
  bar(x->dev);
  foz(117);
}

f2=
void goo() {
  if(b) bar(y->dev);
}


And the new versions are:

f1'=
void foo() {
  bar(x);
  foz(117, 42);
}

f2'=
void goo() {
  if(b) bar(y);
}

In this example there are basically three changes:

x->dev becomes x
y->dev becomes y
foz(117) becomes foz(117', 42)

In this case spdiff will find: (I just ran it to be sure)
@@
expression X0;
@@
- bar(X0->dev);
+ bar(X0);

So the one ungeneralizable change was simply not included. Does this cover
your question Julia?

That seems good.  But perhaps the user would like to know about the 
elements that were not generalizable as well.

julia