Is there a Mercurial equivalent to git log --first-parent?

Question

`git log --first-parent` omits all but the first parent of merge commits. Example: ``` $ git log --oneline --graph * 087f5ed Master C * 36c50a2 Merge branch 'feature' |\ | * 98c89df Feature B | * 89b3a7b Feature A * | 9a95133 Master B |/ * 766c9b0 Master A $ git log --oneline --graph --first-parent * 087f5ed Master C * 36c50a2 Merge branch 'feature' * 9a95133 Master B * 766c9b0 Master A ``` Is there a Mercurial equivalent?

Accepted Answer

Direct equivalent: `hg log -r '_firstancestors(...)'`

There is a direct equivalent: the hidden revset `_firstancestors` follows the first-parent (p1) side of each merge. In Mercurial, like in Git, the first parent is the commit that was checked-out when `hg merge [second parent]` was called.

`hg log -r '_firstancestors(myfeature)'`

'hidden' means that it starts with an underscore, and is not listed in the help etc., but can still be used if you know it exists. I don't know why it is hidden.

Examples

This revset alias lists all commits on a feature branch while ignoring all the ancestry whenever `master` is merged into the branch to bring it up-to-date. (The shop I work prefers merging over rebasing).

```
[revsetalias]
feature($1) = _firstancestors($1) and not _firstancestors(master)

[alias]
f = log -r "feature($(echo $HG_ARGS| sed 's/^f //'))"
```

Example usage (uses my own logging template):

```
$ hg f myfeature
o  423 myfeature default/myfeature -- Esteis -- 2016-07-12 -- 123abc
|  this
o    422 -- Esteis -- 2016-07-12 -- 123def
|\   merge master into myfeature
o ~  421 -- Esteis -- 2016-07-12 -- 456abc
|    that
o  420 -- Esteis -- 2016-07-12 -- 789def
|  and the other
```

Is there a Mercurial equivalent to git log --first-parent?

Solution

Problem