Re: [ANNOUNCE] Git v2.19.0-rc0

[Jeff King <peff@peff.net>]

On Thu, Aug 23, 2018 at 07:40:49PM -0400, Jeff King wrote:

> > You can look for explicitly "if (oidcmp(...))" though. I don't know if
> > you can catch *any* use which degrades to boolean outside of an if
> > statement, but I wouldn't expect there to be too many of those?
> 
> Yeah, that was my thought, too. And I've been trying this all afternoon
> without success. Why doesn't this work:
> 
>   @@
>   expression a, b;
>   @@
>   - if (oidcmp(a, b))
>   + if (!oideq(a, b))
> 
> I get:
> 
>   Fatal error: exception Failure("minus: parse error: \n = File
>   \"contrib/coccinelle/oideq.cocci\", line 21, column 0,  charpos =
>   221\n    around = '', whole content = \n")
> 
> If I do:
> 
>   - if (oidcmp(a, b)) { ... }
> 
> that seems to please the parser for the minus line. But I cannot include
> the "..." on the plus line. Clearly the "..." part should be context,
> but I can't seem to find the right syntax.

This almost works:

  @@
  expression a, b;
  statement s;
  @@
  - if (oidcmp(a, b)) s
  + if (!oideq(a, b)) s

It generates this, for example:

diff -u -p a/bisect.c b/bisect.c
--- a/bisect.c
+++ b/bisect.c
@@ -595,7 +595,7 @@ static struct commit_list *skip_away(str
 
 	for (i = 0; cur; cur = cur->next, i++) {
 		if (i == index) {
-			if (oidcmp(&cur->item->object.oid, current_bad_oid))
+			if (!oideq(&cur->item->object.oid, current_bad_oid))
 				return cur;
 			if (previous)
 				return previous;

which is what we want. But it also generates this:

diff -u -p a/bundle.c b/bundle.c
--- a/bundle.c
+++ b/bundle.c
@@ -369,25 +369,11 @@ static int write_bundle_refs(int bundle_
 		 * commit that is referenced by the tag, and not the tag
 		 * itself.
 		 */
-		if (oidcmp(&oid, &e->item->oid)) {
-			/*
-			 * Is this the positive end of a range expressed
-			 * in terms of a tag (e.g. v2.0 from the range
-			 * "v1.0..v2.0")?
-			 */
-			struct commit *one = lookup_commit_reference(the_repository,
-								     &oid);
+		if (!oideq(&oid, &e->item->oid)) {
+			struct commit *one=lookup_commit_reference(the_repository,
+								   &oid);
 			struct object *obj;
-
 			if (e->item == &(one->object)) {
-				/*
-				 * Need to include e->name as an
-				 * independent ref to the pack-objects
-				 * input, so that the tag is included
-				 * in the output; otherwise we would
-				 * end up triggering "empty bundle"
-				 * error.
-				 */
 				obj = parse_object_or_die(&oid, e->name);
 				obj->flags |= SHOWN;
 				add_pending_object(revs, obj, e->name);

So I really do want some way of saying "all of the block, no matter what
it is". Or of leaving it out as context.

-Peff