git query 'stack()' returns forks in the stack

[pink]

When there's a fork in the graph, is the expected behavior of git query 'stack()' -b still this?

// Note that for a graph like
//
// ```
// O
// |
// o A
// | \
// |  o B
// |
// @ C
// ```
// this will return `{A, B, C}`, not just `{A, C}`.

and if so, is there a way to accomplish getting the latter? For more context, my use case is constructing a stack of branches that I can eventually push to Github, where the chain would look something like master <- branch_a <- branch_c. Using the current ordering of this query would result in master <- branch_a <- branch_b <- branch_c, which isn't correct.

[arxanas]

This is intentional. I often use stack():@, which is all commits in the stack which are reachable from the current HEAD (@).

[pink]

Ahh interesting. Expanding on the previous example, if A, B, and C were each branches, and there were multiple commits between A and B, it seems like git query 'stack():@' -b would exclude branch B from the results if run in between the two.

// ```
// O
// |
// o A
// | \
// |  @
// |   \
// |    o B
// |
// o C
// ```

Is there a way to show commits/branches reachable in either direction?

[arxanas]

If I'm understanding the question correctly, you should be able to get both sides with stack():@ | @:stack(), does that work?

[pink]

Oh nice, yea I think that pretty much works! One related question though - do you know if it's possible to get the closest descendant branch from a commit using git query?

I'm trying to create an alias for only pushing the current branch and its ancestors. Similar to the previous example, the case I'm trying to resolve is when HEAD is in between branches - @:stack() would give me every descendant branch but ideally I'd like to just get the "current" one. I think I can solve this with some scripting instead, but just curious if there's a way to express this with the existing functions.

[claytonrcarter]

If you know you have a non-forking (linear) graph between @ and the next branch, then something like this may work: roots( ( @:stack() & branches() ): )

1. @:stack() - you know this one
2. ... & branches() - limit to commits with branch pointers
3. (...): - all descendants of those branch commits
4. roots(...) - only the root ancestors of the set
5. you could even wrap this in exactly(1, ...) so that it will only succeed if there is 1 matching commit, in case you do call this on a stack w/ a non-linear descendant graph

So I guess your alias may be git submit -c 'exactly(1, roots( ( @:stack() & branches() ): )) ... revsets FTW?!

[arxanas]

You can also write descendants(X) instead of X: if you find it more readable (when X is a big expression).

The function roots(descendants(X)) is common enough that I think it ought to be a built-in function (and likewise for heads(ancestors(X))).

[pink]

@claytonrcarter Whoa that's slick, thanks for the explanation! Spent a while today trying to formulate a query like this - really appreciate both of your help 😄.