From: Philip Oakley Date: Mon, 19 Sep 2016 19:31:55 GMT Subject: Re: clarification of `rev-list --no-walk ^`? Message-ID: <989F47918A374EEF8C7FECD3CFC6767E@PhilipOakley> In-Reply-To: From: "Junio C Hamano" > Michael J Gruber writes: > >>> It can be read that >>> >>> $ git cherry-pick maint next >>> >>> would pick two single commits, while >>> >>> $ git cherry-pick maint next ^master >>> >>> could implicitly be read as >>> >>> $ git cherry-pick maint next --do-walk ^master > > You can read it as "master..next maint" that does force walking. > >>> Clearly that's not what is intended, which is >>> >>> $ git cherry-pick --do-walk maint next ^master > > I do not see the distinction betwee the above two you seem to be > trying to make. Care to explain? > >>> but it is open to interpretation as to where in the command line the >>> caret >>> range prefix's --do-walk (to countermand the --no-walk) should applied. > > I do not think it can be position dependent. OK. (background, long story) When I first read the man page, and in trying to explain a user confusion between cherry pick commits and am'ing the same commits via format-patch (where sometimes the patches had coverlapping context issues), I was trying to confirm for myself that 'git cherry-pick B C' and 'git cherry-pick C B' should get the same end result, and not be mistaken (e.g. user misunderstanding) for a range. I first spotted the 'git help cherry-pick's line: - no traversal is done by default, as if the --no-walk option was specified, see git-rev-list(1). So off I goes to rev-list, and see that the options no-walk/do-walk are said (implied) to be position dependent. --do-walk - Overrides a previous --no-walk. Meanwhile the --no-walk option says: --no-walk - This (option) has no effect if a range is specified. So at this point I am wondering about the command line ordering and what comprises the range if the negative ref is given last, or at least just before a --do-walk. Thus (at this point) it felt like one of those specification rabbit-holes that I often see at $dayjob. It was unclear as to the point at which the 'range' was to be applied in to the command line to get the expected examples. Climbing back out of the rabbit-hole. I now see that after the end of the cherry-pick line I quoted, there is a secondary "Note that specifying a range will feed all . arguments to a single revision walk", which at the time did not register (a classic human error.. Three Mile Island et al.). Similarly, in the rev-list --no-walk option, its says (mid-para) "This has no effect if a range is specified." so in some ways that confirms the cherry pick statement, but again a less obvious corollary. However, there is still a small step missing, which is to confirm that using a negative ^ref anywhere(?) makes the whole list of refs into a range (i.e. it will look-back along the command line) to cancel any --no-walk options in place. Given that a walk usually requires a range, I'm now having difficulty seeing how the --no-walk --do-walk can be combined anyway. The bits I felt was missing (in the docs) was to say explicitly somewhere that a negative ref defined that we had a range (to link back to those walk-no-walk statements), and the extent of rev paramaters it applied to. And after re-reading, that some of those corollary statements about ranges flipping the walk-no-walk condition should be brought forward to be more obvious within the primary rev-list (to avoid the typical reader error). > Philip probably has a > confused notion that "rev-list A..B C..D" is somehow a union of set > A..B and C..D? That wasn't the issue. Though it does beg the question that it's the same as "rev-list D B ^A ^C" isn't it? > >>> If the user did want just the single commit at the tip of maint, and >>> then >>> the range master..next, what would be their command line, and also, how >>> would the man page warn against false expectations? > > Yeah, this can show us that all of the have is coming from that > exact confusion I suspected Philip has. We need to clarify in the > documentation that rev-list set operation does *NOT* have union of > multiple sets to unconfuse the readers. I'd say it was the walk - no walk range confusion. Inclusion of any range definition of any sort (in particular ^rev) causes the expectation that an ordered list of single revs can be included, to be broken. i.e. cherry-pick B D F G Q..T; isn't B D F G R S T, is it? I've also have a quick browse of the test scripts and didn't see any tests that actually cover the example of `git cherry-pick maint next ^master` where both have multiple commits to pick, so couldn't see what the test would expect. -- Philip